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The Ftape-FAQ
Johan De Wit, <jo@correct.nl>
v0.2, 07 december 1997
This is a very incomplete attempt to create a FAQ for the Ftape Floppy
Tape Device Driver. Any suggestions, remarks ... that could improve
this FAQ are welcome indeed. The most recent version of this FAQ can
be found at <http://www.correct.nl/~ftape/>
______________________________________________________________________
Table of Contents
1. A Word From The Maintainer Of Ftape.
2. "Compiling and installing Ftape" related questions !
2.1 What Ftape version should I use?
2.2 I'm having problems getting my XYZ drive to run under the 2.0.xx kernel with the built-in driver. How do I fix this?
2.3 I'm running Linux/SMP and the system just freezes when trying to access the Ftape devices!
2.4 Why does depmod complain about "undefined symbols"?
2.5 "insmod" says the kernel version is wrong
2.6 "insmod" says that kernel 1.2.0 and 1.2.0 differ
2.7 Trying to compile Ftape gives me the error "modversions.h: no such file or directory"
2.8 What is this versioned symbols stuff anyway?
2.9 I seem to be getting sftape instead of zftape. When I run "ftmt status" command, I get output that the Ftape docs says corresponds to sftape ( /dev/qft0: Invalid argument ). Why?
2.10 My Ditto DASH/FC-20/Exabyte Accelerator card works under Microsoft Windows, but I get a drive not found type of error in /var/log/messages when trying to use it under Linux.
2.11 Ftape DMA transfers gives ECC errors
2.12 Help! I'm getting 'dmaalloc() failed' in my syslog file.
2.13 Syslogd works overtime when running Ftape
2.14 How do I change the trace-level?
2.15 I'm having problems with Ftape. I'm using the latest version of Ftape from the Ftape Home Page and believe that I've located a real bug. What should I do?
3. "Using Ftape" related questions !
3.1 How fast is Ftape ?
3.2 When I write to some of my tapes, they seem to spend a lot of time "shoe-shining," or repositioning instead of streaming. Is something wrong with my system?
3.3 Do I have to reboot to the DOS world to format tapes?
3.4 Is it possibly to format Ditto 2GB tapes with ftape?
3.5 Is it possibly to format Ditto Max or Max Pro tapes with ftape?
3.6 Ftape detects more bad sectors than DOS on QIC-3020 tapes
3.7 Is it ok that I'm not hearing the tape move when I do a fsf or a bsf with mt?
3.8 Why does my XYZ backup program complain about "Invalid argument" errors?
3.9 I/O errors and FDC - some explanations.
3.10 Why do I get "/dev/qft0: No such device" errors?
3.11 I get "device busy" when I make multiple backups on a tape using some script.
3.12 How do I "..." with tar?
3.13 What block-size should I use with tar ?
3.14 Where can I find the tar/mt/cpio/dd binaries - sources - manpages?
3.15 If I use tapers compression, is it a bad idea to use the compression with zftape, or would it be better to not use tapers compression, and let zftape do it?
3.16 How does zftape compression compare to say gzip -9?
3.17 I don't trust compression, but hear that the sftape interface is going away. What should I do?
3.18 Ftape says "This tape has no 'Linux raw format"
3.19 Can I exchange tapes with someone using DOS?
3.20 How does `mt eom' work when you've started overwriting a tape in the middle?
3.21 When I made backups before using taper, under the 2.0.29 ftape my drive didn't support fsf, under the new zftape it does, why would this be, and what exactly is fsf ?
3.22 What exactly is the difference between ftape, and zftape?
3.23 What is the difference between a rewinding, and non rewinding drive?
3.24 Can someone tell me how to use mt to rewind my TR-3 drive one record using zftape record, so I can verify it?
3.25 By non-rewinding, they mean that it doesn't automatically rewind, correct? It doesn't mean that under no circumstances it will rewind, right? I tried using /dev/zqft0, and it instantly rewinds the tape.
3.26 What is the difference between what mt considers a record and what it considers a file?
3.27 Reusing tapes with zftape without reformatting the tape.
3.28 This script implements a simple contents listing for the zftape package using the "MTIOCVOLINFO" ioctl.
4. "Tape and Drivers" related questions !
4.1 What are good makers of Travan tapes?
4.2 Where can I obtain the QIC standards?
4.3 Is the Iomega Ditto 2GB drive supported?
4.4 Is the Iomega Ditto Max drive supported?
4.5 Is the Iomega Ditto Max Pro drive supported?
5. Miscellaneous !
5.1 How to subscribe to the Ftape Mailing List?
5.2 How to un-subscribe from the Ftape Mailing List?
5.3 Links to related information.
______________________________________________________________________
1. A Word From The Maintainer Of Ftape.
This is a very incomplete attempt to create a FAQ for the Ftape Floppy
Tape Device Driver.
You might encounter references to the following addresses while
reading this document:
<20> The maintainer of the Ftape FAQ :
Johan De Wit <jo@correct.nl>
<20> The Ftape maintainer :
Claus-Justus Heine <claus@momo.math.rwth-aachen.de>
<20> The Ftape Home Page :
<http://www-math.math.rwth-aachen.de/~LBFM/claus/ftape/>
<20> Mirrors of the Ftape Home Page :
<http://www.torque.net/ftape/>
Thanks to Grant R. Guenther <grant@torque.net>
<http://www.info-systems.com/ftape/>
Thanks to Jakob Curdes <jc@info-systems.com>
<http://www.newwave.net/~joshg/ftape/>
Thanks to Josh Goins <joshg@newwave.net>
<20> The Ftape HOWTO :
<http://sunsite.unc.edu/LDP/HOWTO>
<20> The Ftape Mailing List :
<linux-tape@vger.rutgers.edu>
There is surely quite a lot missing. Please feel free to improve this
FAQ. The preferred way of doing this is to post to the Ftape Mailing
List in case you have a question that isn't answered here.
Also, if you are already reading the list regularly and have the
impression that some questions occur again and again, feel free to
send that question and possibly an answer in the format indicated
below to the maintainer of the Ftape FAQ AND to Ftape Mailing List.
If you make FAQ related postings, then please DON'T FORGET to prepend
the word "[FAQ]" to the subject of your posting. Please don't add the
word "FAQ" to the subject if you post something that isn't related to
the FAQ.
That's all for now.
Claus-Justus Heine.
2. "Compiling and installing Ftape" related questions !
2.1. What Ftape version should I use?
Always the latest stable version which is _supposed_ to be available
from ftp://sunsite.unc.edu/pub/Linux/kernel/tapes and http://www-
math.math.rwth-aachen.de/~LBFM/claus/ftape/
At time of this writing the latest stable version is ftape-4.02.
<answer from Claus Heine>
2.2. I'm having problems getting my XYZ drive to run under the 2.0.xx
kernel with the built-in driver. How do I fix this?
The default version of Ftape included in the 2.0.xx kernel sources is
2.08 or 2.09 and is very out of date. Please update the Ftape drivers
to the latest from the Ftape Home Page.
<answer from Tim Jones>
2.3. I'm running Linux/SMP and the system just freezes when trying to
access the Ftape devices!
You need to add -D__SMP__ to the KERNEL_OPT variable in the file
MCONFIG. In newer ftape versions you only need to uncomment a certain
line in the MCONFIG file.
<answer from Claus Heine>
2.4. Why does depmod complain about "undefined symbols"?
Ignore the depmod error messages. The problem is that the Ftape
modules have to be compiled without the version checksum feature (i.e.
CONFIG_MODVERSIONS) with 2.0.* kernels. This causes no problem, even
when the modules are used with a kernel that has support for this
feature; only that depmod wrongly complains about undefined symbols.
Ignore the complaints of depmod and try to insert the modules despite
of these complaints:
modprobe zftape
If this fails, something is wrong.
<answer from Claus Heine>
2.5. "insmod" says the kernel version is wrong
The insmod program can check the kernel version against the version
that Ftape was compiled for in two ways: It can directly compare the
kernel version number recorded in the Ftape module against the version
of the running kernel, or, if both the kernel and Ftape is compiled
with versioned symbols, compare the version of the used kernel
symbols.
If you have upgraded your version of GCC to v2.7.0 or later, you must
recompile the modules utilities with gcc v2.7.x.
Newer versions of insmod allows you to "force" insertion of a module
into the kernel, even though the version string is incorrect.
<from the Ftape-Howto>
2.6. "insmod" says that kernel 1.2.0 and 1.2.0 differ
Did you remember to apply the ksyms.c patch to the kernel? If not,
read the README.linux-1.2 file in the source distribution.
<from the Ftape-Howto>
2.7. Trying to compile Ftape gives me the error "modversions.h: no
such file or directory"
The modversions.h file is created when the kernel is compiled with the
configuration item CONFIG_MODVERSIONS turned on. With this option
enabled, the file will be created during the make dep step.
One more handy tip is that a make mrproper will remove
/usr/include/linux/modversions.h. You will need to reconfig the
kernel and do a make dep to get the file back.
<from the Ftape-Howto>
2.8. What is this versioned symbols stuff anyway?
When you say `yes' to CONFIG_MODVERSIONS during `make config', all the
symbols exported by the kernel, i.e: the symbols that the loadable
modules can "see", are augmented to include a checksum across the
types of the call/return parameters. This allows insmod to detect
whether the definition of a variable or function in the kernel has
changed since the time when Ftape was compiled.
This ensures a high degree of safety, such that you do not crash the
kernel because you used an outdated module with your kernel.
If you enable CONFIG_MODVERSIONS in the kernel, make sure you have
-DMODVERSIONS -include /usr/include/linux/modversions.h
uncommented in the MODULE_OPT line in the Ftape Makefile. Conversely,
if you do not have CONFIG_MODVERSIONS enabled, make sure you have it
commented out.
<from the Ftape-Howto>
2.9. I seem to be getting sftape instead of zftape. When I run "ftmt
status" command, I get output that the Ftape docs says corresponds to
sftape ( /dev/qft0: Invalid argument ). Why?
There are (at least) two possible sources of the problem:
<20> All Ftape-3.* versions prior to 3.04 install the modules into
/lib/modules/misc
instead of
/lib/modules/uname -r/misc
As modprobe searches in /lib/modules/misc/ last there might be an old
ftape.o module floating around in /lib/modules/ uname -r/misc which
modprobe finds first (uname -r stands for the kernel version). Remove
the old ftape.o module.
<20> Your kernel has support for Ftape compiled in. Reconfigure your
kernel without support for Ftape (CONFIG_FTAPE) and recompile and
install it.
<answer from Claus Heins>
2.10. My Ditto DASH/FC-20/Exabyte Accelerator card works under
Microsoft Windows, but I get a drive not found type of error in
/var/log/messages when trying to use it under Linux.
You are probably trying to use the same IRQ and DMA settings as your
on-board FDC. This does not work in versions of Ftape prior to 3.03b.
Please update the Ftape Drivers to the latest from the Ftape Home
Page.
<answer from Tim Jones>
2.11. Ftape DMA transfers gives ECC errors
Sadly to say there are some SVGA cards and Ethernet cards that do not
decode their addresses correct. This typically happens when the Ftape
buffers are in the range 0x1a0000 to 0x1c0000. Somehow, the DMA write
cycles get clobbered and every other byte written gets a bad value
(0xff). These problems are reported to happen with both SVGA and
Ethernet cards. We know of at least one (bad?) ATI 16bit VGA card
that caused this.
The easiest solution is to put the card in an 8bit slot (it is often
not enough to reconfigure the card to 8bit transfers). Moving the
Ftape buffer away from the VGA range is only a partial solution; All
DMA buffers used in Linux can have this problem! Let us make this one
clear: This has nothing to do with the Ftape software.
<from the Ftape-Howto>
2.12. Help! I'm getting 'dmaalloc() failed' in my syslog file.
You should only see this is you are trying to insmod the ftape.o
module. Try running swapout first. It is provided with the
standalone Ftape source. It doesn't appear in the Ftape source that's
provided with the kernel.
Here's an example of how you can set your rc.local file to use it.
# Install the Floppy Tape Driver
if [ -f /boot/modules/`uname -r`/misc/ftape.o ]; then
echo Installing ftape for Linux `uname -r`
swapout
insmod /boot/modules/`uname -r`/misc/ftape.o
fi
Please note that you won't have this type of problem if you compile
the Ftape driver into the kernel.
<from the Ftape-Howto>
2.13. Syslogd works overtime when running Ftape
The compile-time options NO_TRACE and NO_TRACE_AT_ALL in Ftape control
the amount of system logging. Add whichever is appropriate to the
FTAPE_OPT line in the Makefile and recompile.
<from the Ftape-Howto>
2.14. How do I change the trace-level?
There are three ways you can do this (in order of personal
preference).
While we're at it, here are the meanings of the various trace levels.
<20> 0 Bugs
<20> 1 + Errors
<20> 2 + Warnings
<20> 3 + Information
<20> 4 + More information
<20> 5 + Program flow
<20> 6 + FDC/DMA info
<20> 7 + Data flow
<20> 8 + Everything else
1. Using insmod to change trace-level
If you are using the modules mechanism to load the Ftape driver,
you can specify the tracing level as an option to the insmod
command.
/sbin/insmod ftape.o tracing=<tracing-level>
2. Using mt to change trace-level
The Ftape driver has a hack in it that allows the fsr option in mt
to be used to set the tracing level. zftape does not have this
hack.
mt -f /dev/ftape fsr <tracing-level>
The use of the fsr command in mt is a hack, and will probably disap<61>
pear or change with time.
3. Recompiling to change trace-level
The file tracing.c contains a line int tracing = 3;. Change the 3
to whatever is appropriate and recompile.
<From the Ftape-Howto>
2.15. I'm having problems with Ftape. I'm using the latest version
of Ftape from the Ftape Home Page and believe that I've located a real
bug. What should I do?
Check the Ftape Home Page. for an even newer version. Then check the
FAQ contained in the that package if your problem is listed there.
Next, try to check if the manual that comes with the Ftape
distribution mentions your problem.
There is no need to read the entire manual, simply check the "Concept
Index" if it contains a keyword that might be related to your problem,
then jump to the proper location in the manual.
If you are still convinced you've found a bug, then post a general
question describing the problem to the Linux-Tape Mailing List , but
do not attach your entire Ftape error-log. If we've seen the problem
before, we'll let you know where the resolution effort stands. If we
haven't, the Ftape maintainer will most likely request that you send
him the entire Ftape error-log (snipped from your system messages
file).
<answer from Tim Jones>
3. "Using Ftape" related questions !
3.1. How fast is Ftape ?
You can achieve quite respectable backup and restore speeds with
Ftape: a Colorado DJ-20 and an Adaptec 1542CF controller, has been
measured at 4.25Mbyte/min sustained data transfer rate (no
compression) across a 70Mbyte tar archive, while comparing the archive
on the tape with data on an IDE disk. The speed of Ftape is mostly
dependent on the data transfer rate of your FDC: The AHA1542CF has a
``post-1991 82077'' FDC, and it will push 1Mbit/sec at the tape drive.
If you have an FDC which can only deliver 500Kbit/sec data rates, you
will see half the transfer rate (well, roughly).
3.2. When I write to some of my tapes, they seem to spend a lot of
time "shoe-shining," or repositioning instead of streaming. Is some<6D>
thing wrong with my system?
There has been a few reports of "shoeshining". This is when the tape
just seems to run back and forth endlessly. This has been seen on a
Jumbo 250 (74407.3051@compuserve.com) and on an Iomega 250 Ditto
Insider (tom@opus.cais.com). In the latter case it has been narrowed
own to using an ELF Linux and running off a SCSI hard disk (connected
to an Adaptec 1542cf). Please contact me if you have an update to
this problem.
<from the Ftape-Howto>
Probably not. If you are backing up a large number of < 2K files,
you're just going to have to live with it. In this event, the
repositions are caused by file system access overhead. If you are
backing up a normal system's files, this may be caused by slop or
media stretching in the tape cartridge. By simply retensioning the
tape, you should see this go away. Try
ftmt -f /dev/zqft0 reten
to retension the tape. If retensioning doesn't solve this, and it's
only happening on certain tapes, it might be wise to replace the tapes
in question.
<answer from Tim Jones>
If you use afio as your backup tool you can set it to write a very
large number of buffers in one hit by using the -c flag. Make it large
enough so that you supply enough data for most of a single end-to-end
pass over the tape. For my system, the following streams quite nicely
- stopping relatively few times per tape pass on an unloaded system:
find /usr/local -xdev -print | afio -o -v -f -b 10240 -c 800 /dev/qft0
In my case I'm writing 800 x 10240 bytes per tape write, i.e. about
8MB. haven't experimented that much with these settings - so someone
might like to establish more optimal ones.
Presumably other backup utilities could be modified to use a similar
technique.
<answer by Michael Hamilton>
GNU tar doesn't use buffering in this way. The commercial backup
program "bru" is able to multi-buffer using shared memory; this works
only when writing compressed archive with bru (regardless whether you
use Ftape's builtin compression)
Another way to overcome the problem might be to use more dma buffers
in the Ftape kernel driver like:
mt -f /dev/qft0 setdrvbuffer $((6*32786))
$((6*32786)) should be expanded by your shell when using a Bourne com<6F>
patible one. This has a negative impact on the system's memory pool:
Ftape's dma buffers cannot be used by any other part of the kernel nor
by any other application. And kernel memory cannot be swapped out. If
you decide to use this kind of multi-buffering then you should unload
the driver as soon as it isn't needed any longer.
<answer by Claus Heine>
3.3. Do I have to reboot to the DOS world to format tapes?
Not if you are using the latest version of the Ftape drivers from the
Ftape Home Page.
To format a QIC-80, TR-1, TR-3, QICWide 3010 or 3020 tape, get the
latest version of ftape and the latest version of the ftape-tools
package (from the same location) and read the documentation of the
ftformat utility which is included in the ftape-tools package.
(* Do not try to format Ditto 2GB tapes. *)
(* Do not try to format Ditto Max or Max Pro tapes. *)
<answers from Tim Jones and Claus Heine>
3.4. Is it possibly to format Ditto 2GB tapes with ftape?
It isn't possible to format Ditto 2GB tapes with Ditto 2GB tape drive,
and it isn't possible at all to re-format Ditto 2GB tapes in a way
that they still can be used by a Ditto 2GB tape drive.
This is a hardware limitation of the Ditto 2GB tape drive. It can't be
helped at the software level, i.e. it isn't ftape's fault.
3.5. Is it possibly to format Ditto Max or Max Pro tapes with ftape?
No, the Ditto Max can't format tapes.
This is a hardware limitation of the Ditto Max (Pro) tape drive. It
can't be helped at the software level, i.e. it isn't ftape's fault.
3.6. Ftape detects more bad sectors than DOS on QIC-3020 tapes
If you look at the difference, you will notice that Ftape always
detects 2784 sectors more than DOS.
The number that Ftape reports is correct (of course :-). Each
correctly formatted QIC-3020 tape has 2784 sectors at fixed positions
that are marked in the bad sector map. To quote from the specs:
Tracks 5,7,9,11,13,15,17,19,21,23,25 and 27 within 4 seg<65>
ments of either EOT or BOT are prone to increased error
rates due to hole imprints. Therefore, these regions shall
be mapped as bad at format time and entered in the bad sec<65>
tor map by indicating that all sectors within the identified
segments are bad.
This gives 12 tracks * 2 * 4 segments * 29 sectors == 2784 sectors.
So Ftape choose to report the real number of sectors that cannot be
used on the tape, while DOS gives a more optimistic number giving a
better indication of tape quality. (Ftape's behavior might change in
the future to detect correct formatting and display the separate
numbers. It has rather low priority though).
QIC-3010 are alike QIC-3020 tapes regarding this.
<from the Ftape-Howto>
3.7. Is it ok that I'm not hearing the tape move when I do a fsf or a
bsf with mt?
Yes. The driver merely updates an internal counter when those
commands are issues. The tape should move to the proper location on
the next read or write access to the tape drive.
<from the Ftape-Howto>
3.8. Why does my XYZ backup program complain about "Invalid argument"
errors?
zftape requires the data to be written in multiples of a fixed minimal
block size. This is a very usual behavior for a tape device. There are
three ways to get rid of those errors:
<20> set Ftape's block size to the block size used by the backup
program. The example below works for "afio":
mt -f /dev/qft0 setblk 5120
<20> If you don't want to use Ftape's built in compression you can also
use
mt -f /dev/qft0 setblk 0
to switch Ftape to variable block size mode and be able to write the
data in arbitrary portions to the tape (BUT: the builtin compression
doesn't work with this setting). When you intend to use "KBackup" then
this is the only way to make it work together with Ftape (it _may_
work, don't know if it does)
<20> tell your backup program about Ftape's default block size of 10k
(which is also the default of GNU tar). For "afio" you can use the
following command line switch:
afio -b 10k ...
You may want to read the section "Tape blocks" of the manual (use its
"Concept index" to directly jump to that section)
When using GNU tar's builtin compression with GNU tar versions prior
to tar-1.12 one needs to run tar with the --block-compress switch to
re-block the output to the tape. Otherwise tar will compress the data
it reads, and write it in arbitrary portions to the tape.
Example :
tar -czvf /dev/qft0 --block-compress /etc
WARNING: One shouldn't use tar's builtin compression with large
backups as it makes the entire data stream one huge compressed block.
If such archives are corrupted right at the beginning it will be very
difficult to recover.
<answer by Claus Heine>
3.9. I/O errors and FDC - some explanations.
When you get next messages, this could be interesting for you !
<20> fdc-io.c (ft_handle_perpend) - Your FDC does not support QIC-3020.
<20> Cannot write to /dev/qft0: I/O error
The explanations:
"FDC" menas "Floppy Disk Controller". The problem is that your floppy
disk controller must be able to support something that is called
"perpendicular mode" to be able to read and write QIC-3020/QIC-3010
cartridges (i.e. TR-3 cartridges). To my knowledge all FDCs that are
capable of at least 1Mbit/sec data transfer rate also support
"perpendicular mode" ("perpendicular" refers to the direction of
magnetization of the ferro-magnetic particles on the tape).
This means that you need to purchase another FDC. Either look around
some computer stores and ask for an IO controller cards that is able
to support 2.88 Mb floppies (which imlies 1Mbit data transfer rate and
perpendicular mode).
Or get one of the so called "high speed" controllers that even support
2Mbit/sec data transfer rate. Those controllers are based on an Intel
82078 FDC. Iomega sells such a card under the name "Ditto Dash". I
think Exabyte sells their 2Mbit controllers separately, too, whereas
Seagate ships its TR-3 drives (i.e. the TST-3200) together with such a
controller.
<answer from Claus Heine>
3.10. Why do I get "/dev/qft0: No such device" errors?
I assume that the following is the problem: The Ftape module is loaded
OK into the kernel:
/usr/src/ftape-3.03b-970603# lsmod
Module Pages Used by
ftape 22 0
but then this happens:
$ ftmt -f /dev/qft0 status
ftmt: /dev/qft0: No such device
Solution You need to load the zftape.o module as well. With Ftape-3.*
the ftape.o module doesn't implement the VFS interface. This is done
by zftape.o.
<answer from Claus Heine>
3.11. I get "device busy" when I make multiple backups on a tape
using some script.
The "device busy" messages can only occur while the Ftape devices are
still held open by some program. As soon as the close() system call
has completed the busy flag is cleared. May be "bru" or some other
program has still forked off a child that dies delayed?
Yes, this will reproduce the problem, it seems:
tar -cvvzf /dev/nqft0 --block-compress ; mt rewind
You can skip the "--block-compress" if using the most recent version
of GNU tar.
However, this is not a bug of Ftape. It seems that the parent tar
process exits before its child has closed the tape device. I know,
however, from hacking the tar code ages ago, that tar properly waits
for its parent to die.
However, the busy message simply means that the "busy" variable is
still held at 1 (zftape/zftape-init.c). And this simply means that
there still is a process hanging around that holds the tape device
open.
I think I have it (only for the case of tar 'cause I have the source
code.
If on uses tar with compression, then it forks a child which will
become the compressor bei execing "gzip" or whatever. Before the call
to execlp() the child will fork off a grand child of its parent tar.
That grandchild will do the actual tape I/O.
tar - fork() - write to child tar
|
child tar - fork() - gzip (will pipe to grand child tar)
|
grand child tar - open archive.
Now, parent tar only waits for its child to die. gzip surely doesn't
wait for the grand child as the gzip is a result of an execlp().
What I don't know is whether the grand child should be implicitly
waited for by the parent tar, or if the wait() function also waits for
grand childs.
But this seems to be the problem: the parent tar already has exited
while its grandchild still is busy closing the archive. One hardly
will notice this problem if the close() happens fast (i.e. regular
files, block devices, also other tape devices?), but it isn't a bug in
Ftape, but either in the backup programs or in the kernel or maybe
libc exit code.
Don't know if the considerations above also apply to bru. If there is
no grandchild and the parent process properly waits for its childs
then there shouldn't be a problem.
<answer from Claus Heine>
3.12. How do I "..." with tar?
These are really tar questions: Please read the man page and the info
page. If you have not got it either, try
tar --help 2>&1 | less
If your version of tar is v1.11.1 or earlier, consider upgrading to
v1.11.8 - This version can call GNU zip directly (i.e.: it supports
the -z option) and has an elaborate help included. Also, it compiles
right out of the box on Linux.
<from the Ftape-Howto>
3.13. What block-size should I use with tar ?
When using compression, and in all general, it can be a benefit to
specify to tar, that it should block the output into chunks. Since
Ftape cuts things into 29Kbyte blocks, saying `-b58' should be
optimum.
"Why 29Kbyte?", I hear you cry. Well, the QIC-80 standard specifies
that all data should be protected by an Error Correcting Code (ECC)
code. The code specified in the QIC-80 standard is known as a Reed-
Solomon (R-S) code. The R-S code takes 29 data bytes and generates 3
parity bytes. To increase the performance of the ECC code, the parity
bytes are generated across 29 1Kbyte sectors. Thus, Ftape takes
29Kbytes of data, adds 3Kbytes of ECC parity, and writes 32Kbytes to
the tape at a time. For this reason, Ftape will always read and write
32K byte blocks to be able to detect (and correct) data errors.
If you are curious, and wish to know more, look in the ecc.c and ecc.h
files, for an explanation of the code and a reference to a textbook on
Reed-Solomon codes.
<from the Ftape-Howto>
3.14. Where can I find the tar/mt/cpio/dd binaries - sources - man<61>
pages?
All of these tools have been developed by the GNU project, and the
source (and man page) can be fetched from just-about any ftp site in
the world (including ftp.funet.fi, tsx-11.mit.edu, and
sunsite.unc.edu). In any case they can be fetched from the official
GNU home site: prep.ai.mit.edu [18.71.0.38]:/pub/gnu. The latest
versions (as of September 12 1996) are:
cpio: 2.4.2 (cpio-2.4.2.tar.gz)
dd: 3.13 (fileutils-3.13.tar.gz)
mt: 2.4.2 (cpio-2.4.2.tar.gz)
tar: 1.11.8 (tar-1.11.8.tar.gz)
gzip: 1.2.4 (gzip-1.2.4.tar.gz)
They all compile out of the box on Linux v1.0.4 / libc v4.5.19 / gcc
v2.5.8.
<from the Ftape-Howto>
3.15. If I use tapers compression, is it a bad idea to use the com<6F>
pression with zftape, or would it be better to not use tapers compres<65>
sion, and let zftape do it?
It is not bad as such to compress data twice (which would be the case
when using tapers compression together with zftape's compression) but
it doesn't make any sense. You won't gain much further compression,
but only waste CPU cycles.
Tapers compression should be quite safe, as taper compresses single
files; in contrast to tar -czf ... which makes the entire data stream
a large compressed block of data, which is really a bad thing with
serious backups as a single bad byte at the beginning of the archive
can make the entire archive unusable, well, it will be at least quite
difficult to recover.
<Answer from Claus Heine>
3.16. How does zftape compression compare to say gzip -9?
gzip -9 is better (i.e. one gains higher compression). zftape's
compression is comparable with the Un*x compress program, but should
be faster, and is faster than gzip.
<Answer from Claus Heine>
3.17. I don't trust compression, but hear that the sftape interface
is going away. What should I do?
Use the zftape interface, but don't load the zft-compressor module.
The device then becomes /dev/qft0.
<answer from Tim Jones>
3.18. Ftape says "This tape has no 'Linux raw format"
You get this complaint if you haven't erased your freshly formatted
tape. This is because Ftape expect a "magic header" on the tape, to
be able that it is allowed to interpret the header segment in its own
way (eg: file marks). To remove the problem, say
mt -f /dev/nftape erase
<from the Ftape-Howto>
3.19. Can I exchange tapes with someone using DOS?
No. The DOS software conforms to the QIC-80 specs about the layout of
the DOS filesystem, and it should(?) be a small problem to write a
program that can read/write the DOS format. In fact, I'd bet that
creating a nice user interface would be a bigger problem.
<From the Ftape-Howto>
3.20. How does `mt eom' work when you've started overwriting a tape
in the middle?
(EOM is "End Of recorded Media", the position right after all data
already recorded to the tape)
One cannot use tape "files" like files on an ordinary file system.
In principle, a tape doesn't allow anything but appending new data at
EOM. However, if one positiones just in the middle of the already
recorded data AND starts writing, then the driver first deletes all
following files (thus moving the EOM to the actual position) and then
starts writing.
Thus, the new EOM after finishing the write process, is then after the
newly recorded data.
One of the consequences of the above is, of course, that writing to
the tape in the middle of the already recorded area, is destructive in
the sense, that it not only overwrites the "file" the tape is
positioned at, but also deletes all following files.
<from the Ftape-Howto> <Answer from Claus Heine>
3.21. When I made backups before using taper, under the 2.0.29 ftape
my drive didn't support fsf, under the new zftape it does, why would
this be, and what exactly is fsf ?
It probably didn't work before because you didn't use a
mt -f /dev/rft0 erase
before writing data to the cartridge. THIS ISN'T necessary any more.
But, hey, what does mt fsf? Tape drives don't store files in the sense
that you can use
cp somefile /dev/my_what_ever_tape
or be able to mount the tape drive like you could mount a harddisk.
You can't do nothing with a tape drive but write data to it in a
sequential manner.
As this is quite inconvenient, somebody invented something which is
known under the name file mark or eof mark (eof == End Of File). Those
marks don't separate files that have been backed up to the tape
device, but only separate blocks of data (whatever data that might
be).
Normally, the kernel tape device drivers take care of writing file
marks when the tape device is closed, i.e.
tar -cf /dev/nqft0 /bin
tar -cf /dev/nqft0 /etc
mt -f /dev/nqft0 rewind
would result in a backup of all files under /bin and /etc. When the
first tar finishes, the kernel driver will take care of writing a file
mark to the tape at the the current tape position, and when the second
tar process has finished, another file mark is written to the tape
cartridge at that position.
Now, the sense of those file marks is, that it is possible to skip
between different archives on the tape more quickly than would be
possible with reading the data back.
The commands to do that are:
mt fsf
fast skip to the next file mark towards EOT (End Of Tape)
mt bsf
fast skip to the next file marks towards BOT (Begin Of Tape)
Thus, to extract the second archive in the example above, one doesn't
need to read the first archive back, but can proceed as follows:
mt -f /dev/nqft0 rewind
mt -f /dev/nqft0 fsf
tar -xvf /dev/nqft0
<Answer from Claus Heine>
3.22. What exactly is the difference between ftape, and zftape?
When Ftape was young there were two versions of the floppy tape
driver, one of them was called zftape because of its built-in user-
transparent on-the-fly compression. Whether such a thing is a feature
or a bug ('cause this needn't be done in kernel space) is another
question. However, the ioctl interface and file mark handling provided
by zftape was much better and had less bugs. And zftape allows to use
floppy tape cartridges with different OS. Well, you can't exchange
data, but zftape won't overwrite volumes created by your Windoze
program, and vice versa.
Nowadays, Ftape is name of the entire floppy tape driver package AND
ftape.o is the file-name of the kernel module that implements the low-
level hardware support. zftape has ceased to exist as a separate
package, but the new Ftape versions (since ftape-3.00) contain a
zftape.o module that needs to be loaded on top of ftape.o (i.e. you
need to load BOTH modules to be able to access your floppy tape drive)
and implements the file system interface and the advanced (?) features
of the previous verions zftape.
<Answer from Claus Heine>
3.23. What is the difference between a rewinding, and non rewinding
drive?
Well, the rewinding tape devices rewind the tape to BOT (Begin Of
Tape) when the device is closed, i.e.
tar -cvf /dev/qft0 /bin
will rewind the tape cartridge when the tar job has finished. In con<6F>
trast,
tar -cvf /dev/nqft0 /bin
will NOT rewind the tape cartridge and leave the tape R/W head at its
current position.
Rewinding devices should be used when performing a single backup, non-
rewinding devices can be useful when doing multiple backups as one
doesn't need to space to EOM (End Of recorded Media) before appending
another archive.
Non-rewinding devices MUST be used when sending any of the tape motion
command to the tape drive, such as
mt -f /dev/nqft0 fsf
, because when the mt process finishes then the tape device is closed
which would result in rewinding the cartridge with the rewinding
devices.
<Answer from Claus Heine>
3.24. Can someone tell me how to use mt to rewind my TR-3 drive one
record using zftape record, so I can verify it?
Well, it depends. If the tape is still positioned inside the volume
just written, "mt bsf 1" (or equivalently "mt bsf") will backspace
just to the beginning of that volume (this is how "tar --verify"
works). If the tape is already positioned AFTER the filemark that
marks the end of the last written volume, then you need to issue "mt
bsf 2"
The logic behind this is as follows: "MTBSF count" backspaces over
count file marks, stops, and then positions on the EOT side of the
last skipped file mark. This means, an "mt bsf 2" will position right
at the beginning of the previous volume.
<answer form Claus Heine>
3.25. By non-rewinding, they mean that it doesn't automatically
rewind, correct? It doesn't mean that under no circumstances it will
rewind, right? I tried using /dev/zqft0, and it instantly rewinds the
tape.
You are right: auto-rewind means, the tape is rewound when the tape
device is closed, non-rewinding means, the tape isn't automatically
rewound when the tape device is closed (but you can, of course, use
the tape motion commands BSF/FSF etc. to position the tape head at
every position you like).
<answer form Claus Heine>
3.26. What is the difference between what mt considers a record and
what it considers a file?
A record is the minimal amount of bytes that will be accepted by the
tape in one read/write operation (except in "variable block size mode"
where it just should be the amount of data actually written in a
single write operation??).
For zftape every read and write access has to be a multiple of a fixed
block size (fixed, but tunable with MTSETBLK). This block size is a
"tape record" (as mentioned in the GNU mt man page and defaults to
10kb for zftape.
A "file" (in the sense of the mt man page) is a, well, misleading
terminus. What is meant is an area of the tape between two file marks.
This is not a file like a file on the file system, in the sense that
it could have a name, file access modes, could be moved or copied with
cp, mv, rm etc.
Instead, It simply is the area of the tape that was recorded in one
backup session, its end is marked by a tape file mark, and its
beginning is delimited by either BOT or the file mark of the previous
tape "file". That tape "files" are the things that can be skipped with
the MTBSF/FSF commands.
<answer form Claus Heine>
3.27. Reusing tapes with zftape without reformatting the tape.
We try to answer the followong questions :
<20> Is there a good way to erase, as in remove the data or at least the
volumes from a tape, without reformating?
<20> Can you overwrite the last volume on a tape with making a mess out
of it?
<20> Can you overwrite the last several volumes without making a mess?
<20> Can you delete the last volume?
If you want to "erase" an entire cartridge, then simply do:
mt -f /dev/qft0 erase
This will erase the volume table (i.e. the "file marks").
Pre-ftape-3.x releases of zftape and ftape used to allow overwriting
of already existing volumes on a cartridge. I have removed this
feature as it was reported that it already has caused data-loss with
some backup programs.
If you indeed need to remove some volumes on the tape then you should
use the
vtblc
program that comes with the ftape-tools package which can be down-
loaded from the same locations as the ftape kernel driver package.
Please refer to the documentation which is contained in the ftape-
tools package for more information.
If you simply want to reuse old tapes, then it suffices to do
mt rewind
If the tape is at BOT (Begin Of Tape) then every write access to the
tape will silently erase all file marks and overwrite the data already
existing on the tape.
<answer by Claus Heine>
3.28. This script implements a simple contents listing for the zftape
package using the "MTIOCVOLINFO" ioctl.
Here is as little perl/bash script that lists the contents of a
cartridge using the zftape specific "volinfo" ioctl. Hope this shows
how to handle this kind of stuff.
What it basically does is the following:
1. Rewind the cartridge
2. Issue the volinfo command:
claus@thales:~$ mt volinfo
file number = 1
block size = 10240
physical space used = 522.0 kilobytes
real size of volume = 520.0 kilobytes
Parse the ouput and place the values in appropriate variables
3. Skip to the next volume with "mt fsf"
4. Exit if this gives an error (EOD), otherwise "goto 2)"
The Perl Script
#!/usr/bin/perl
#
# Copyright (C) 1997 Claus-Justus Heine
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; see the file COPYING. If not, write to
# the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
#
# This script implements a simple contents listing for the zftape
# package using the MTIOCVOLINFO ioctl.
#
$version = <<EOT;
listtape-1.0 -- a perl script to list the contents of a floppy tape cartridge
under Linux using the zftape driver
RCS \$Revision: 1.2 $
RCS \$Date: 1998/08/30 13:43:28 $
EOT
$tapedev = "/dev/tape";
$usage = <<EOT;
Usage: listtape [options ...]
Mandatory or optional arguments to long options are mandatory or optional
for short options too.
-f, --file=FILE Tape device to use. Default is "/dev/tape".
-h, --help Print this help.
-? Same as '-h'.
--usage Same as '-h'.
-V, --version Print version information.
Author: Claus-Justus Heine <claus\@momo.math.rwth-aachen.de>
EOT
while ($ARGV[0] =~ /^-/) {
$_ = shift;
if (/--file/) {$_ = shift; $tapedev = $_; next;}
if (/-f/) {$_ = shift; $tapedev = $_; next;}
if (/--help/) { print $usage; exit 0; }
if (/-h/) { print $usage; exit 0; }
if (/--usage/) { print $usage; exit 0; }
if (/-\?/) { print $usage; exit 0; }
if (/--version/) { print $version; exit 0; }
if (/-V/) { print $version; exit 0; }
die $usage;
}
&open_tape($tapedev, "status");
while(<FTMT>)
{
$online = 1 if (/.*online.*/);
}
if (! $online) { die "No cartridge present.\n"; }
&mtop($tapedev, "rewind");
printf "%11s%12s%20s%20s\n",
"file number", "block size", "volume size", "tape space";
while (1)
{
&open_tape($tapedev, "volinfo");
while (<FTMT>) {
if (/^file number\s*=\s*([0-9]*)$/) { $filenumber = $1; }
if (/^block size\s*=\s*([0-9]*)$/) { $blocksize = $1; }
if (/^physical space used\s*=\s*([[0-9]*.*)/) { $rawsize = $1; }
if (/^real size of volume\s*=\s*([[0-9]*.*)/) { $size = $1; }
}
close(FTMT);
if (&mtop($tapedev, "fsf 1") != 0) {
&mtop($tapedev,"rewind");
print "\nRemaining space: $rawsize\n";
print "Tape block size: $blocksize\n";
exit 0;
}
printf "%6d %5d %20s%20s\n",
$filenumber, $blocksize, $size, $rawsize;
}
sub mtop
{
local ($tape, $operation) = @_;
local ($exitval);
system "ftmt -f $tape $operation > /dev/null 2>&1";
}
sub open_tape
{
local ($tape, $operation) = @_;
local ($command);
$command = "ftmt -f " . $tape . " " . $operation . " |";
open(FTMT, $command) || die "Couldn't open $command -- $!\n";
}
The Bash Script
______________________________________________________________________
#! /bin/bash
#
# Copyright (C) 1997 Claus-Justus Heine
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; see the file COPYING. If not, write to
# the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
#
# This script implements a simple contents listing for the zftape
# package using the MTIOCVOLINFO ioctl.
#
#
# insert better option parsing here
#
TAPEDEV=${1-/dev/tape}
if ! echo $TAPEDEV | grep "/dev/n"
then
TAPEDEV=/dev/n$(basename $TAPEDEV)
fi
if ! [ -c $TAPEDEV ]
then
echo $TAPEDEV is not a character device! 1>&2
exit 1
fi
if ! mt -f $TAPEDEV rewind
then
echo Could not rewind $TAPEDEV - no cartridge present? 1>&2
exit 1
fi
echo -e "\nContents of $TAPEDEV:\n"
printf "%11s%12s%20s%20s\n" "file number" "block size" "volume size" "tape space"
trap "rm -f /tmp/$0.$$" exit
while true
do
if ! foo=$(mt -f $TAPEDEV volinfo |cut -f 2 -d =)
then
echo $TAPEDEV doesn\'t seem to be a floppy tape device 1>&2
exit 1
fi
#
# "echo foo | read foo" will not work as the "read foo" is executed in
# another shell.
#
echo $foo > /tmp/$0.$$
read file blksz used usedunit size sizeunit < /tmp/$0.$$
if ! mt -f $TAPEDEV fsf 1 > /dev/null 2>&1
then
echo -e "\nRemaining space: $used $usedunit"
echo -e "Tape block size: $blksz"
if ! mt -f $TAPEDEV rewind
then
echo Rewind of $TAPEDEV failed 1>&2
exit 1
fi
exit 0
fi
printf "%6d %5d %20s%20s\n"\
$file $blksz "$size $sizeunit" "$used $usedunit"
done
______________________________________________________________________
<answer from Claus Heine>
4. "Tape and Drivers" related questions !
4.1. What are good makers of Travan tapes?
I was the UNIX Product Manager at Archive Corp (Prior to the
Conner/Seagate mess) and we performed extensive tests of tape media
for compatibility certification, including retentivity, flaking and
length consistancy. Based on the results of the tests, we selected
the best of these certified manufacturers' products to private label
as our own media. Here is the order in which we selected vendors up
through 1995 (when I lost contact with the ATI group):
QIC
1. 3M (now known as Imation)
2. QMaxell/Sony (tie)
3. (BTW - Iomega uses Sony private-labelled media)
4MM
1. Fuji
2. Maxell/Sony (tie - is this a trend?)
8MM
1. Fuji/Exabyte - which we believed to be OEM'd Fuji (tie - so
much for trend!)
2. Sony
3. Maxell
DLT
1. Maxell
2. Sony
Otherwise, we had entries in our search from other vendors which were
generally a private-labelled version of one of the major labels above.
The exceptions were Verbatim and DIC. Both of these manufacturer's
media had fall-out rates and length discrepancies that were so high
that we would not certify them and even warned customers about them
indicating that we could not offer any sort of guarantee that they
would get a good backup using the media from these manufacturers.
In addition, since coming to EST, I've found that Verbatim media is
still not worth the money saved in purchasing it. We have 11 of their
TR-Extra and QIC-Extra (QICXL) tapes that were useless after fewer
than 20 passes each.
While this is my personal opinion, it is based on over 9 years of
experience with this very question, I strongly recommend Imation/3M
media for QIC/Travan user, Fuji media 4MM users, Exabyte/Fuji for 8MM
and DEC labelled media for DLT users.
<answer from Tim Jones>
4.2. Where can I obtain the QIC standards?
If you wish to help developing Ftape, or add some utility (e.g. a tape
formatting program), you will need that appropriate QIC standards.
The standard(s) to get is: QIC-80, -117, -3010, and 3020. QIC-117
describes how commands are sent to the tape drive (including timing
etc), so you would probably never need it. QIC-80/3010/3020 describes
higher level part, such as tape layout, ECC code, standard filesystem.
You can get the QIC standards from the following address:
Quarter Inch Cartridge Drive Standards, Inc.
311 East Carrillo Street
Santa Barbara, California 93101
Phone: (805) 963-3853
Fax: (805) 962-1541
Note: They are registered as `Freeman Associates, Inc' in the phone
book.
<from the Ftape-Howto>
4.3. Is the Iomega Ditto 2GB drive supported?
Yes, if you are using version ftape-3.x or later of the Ftape drivers
from the Ftape Home Page or from
ftp://sunsite.unc.edu/pub/Linux/kernel/tapes.
<answer from Tim Jones>
As the Ditto 2GB is a Tr-3 tape (though it can only store 1GB instead
of the 1.6GB you get with a regular Tr-3 drive) you need an FDC (FDC
means: Floppy Disk Controller) that is capable of at 1Mbit/sec
transfer rate. You don't need to worry about this if you have an
accellerator card (i.e. the Ditto Dash controller). Otherwise try to
purchase an FDC that claims to be capable of driving 2.88Mb floppies
because this implies that the FDC is capable of 1Mbit transfer rate.
Ftape prints the maximum data rate of the FDC to the kernel log files
like this:
ftape-ctl.c (ftape_init_drive) - Highest FDC supported data rate: 500 Kbps.
<answer from Claus Heine>
4.4. Is the Iomega Ditto Max drive supported?
Yes, if you are using version ftape-4.02 or later of the Ftape drivers
from the Ftape Home Page or from
ftp://sunsite.unc.edu/pub/Linux/kernel/tapes.
<answer from Claus Heine>
4.5. Is the Iomega Ditto Max Pro drive supported?
Yes. But if you want to use the 5GB (10GB with compression) cartridges
you don't need it. With ftape there doesn't seem to be any difference
between the Ditto Max and the Ditto Max Pro.
<answer from Claus Heine>
5. Miscellaneous !
5.1. How to subscribe to the Ftape Mailing List?
You can subscribe to that list by sending mail to
majordomo@vger.rutgers.edu
with the single line
subscribe linux-tape
in its body. Please store the answer you get from majordomo in a safe
place because it contains instructions how to UNSUBSCRIBE from the
mailing list.
<answer from Claus Heine>
5.2. How to un-subscribe from the Ftape Mailing List?
Send mail to
majordomo@vger.rutgers.edu
with the single line
unsubscribe linux-tape MY@EMAIL.ADDRESS
where MY@EMAIL.ADDRESS has to be replaced by the the email address
that you used when subscribing to the list. Note that you must have
received an email with instructions how to unsubscribe from the mail<69>
ing list at the time you subscribed to it.
<answer from Claus Heine>
5.3. Links to related information.
<http://www.uwsg.indiana.edu/usai/library/backups.html>
More links wanted !!!
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