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<H2><A NAME="s4">4. Using a Jaz Disk</A></H2>
<H2><A NAME="ss4.1">4.1 DOS Formatted Disks</A>
</H2>
<P>Jaz disks come pre-formatted from Iomega with a single partition using
the DOS FAT16 file system. The single partition is usually the 4th disk
partition (for Mac compatibility - the Mac requires data to be on the 4th
partition, but the PC doesn't care which partition data is on).
<P>Linux is perfectly happy reading and writing a FAT16 file system, so you
can use the disk as is. In order to use the disk, you need to mount it, so
the first thing you need to do is create a mount point. For this document,
we'll mount all our DOS Jaz drives under <CODE>/dos_jaz</CODE>, so let's create
that mount point (you'll need to be root for most of this stuff). You'll
only need to do this once:
<P><CODE>mkdir /dos_jaz</CODE>
<P>In a previous section, I mentioned you'd need to remember the Jaz drive's
raw SCSI device name. You need that now. If your drive is
<CODE>/dev/sda</CODE> then all these examples will work for you. If not, you'll
need to replace "sda" with the device ID of your Jaz drive. Since you need
to issue these commands as root, you'll want to be sure you have the correct
names.
<P>If you have a 2.0 kernel, or have added VFAT support, you can mount the
Jaz disk this way, and have long filenames under FAT16:
<P>
<P><CODE>mount -t vfat /dev/sda4 /dos_jaz</CODE>
<P>Note that although VFAT allows you to use long filenames, those filenames
are still case <EM>in</EM>-sensitive, and although 'ls' lists permissions,
you can't actually change permissions on any of the files.
<P>If the "vfat" format is not recognized by the mount command, then you'll
use this command to mount the Jaz disk:
<P><CODE>mount -t msdos /dev/sda4 /dos_jaz</CODE>
<P>Once you have issued either of the mount commands, files from the disk
will appear under the <CODE>/dos_jaz</CODE> directory. While the disk is
mounted, you will not be able to eject it.
<P>When you are done with the disk, you can unmount it with the command:
<P><CODE>umount /dos_jaz</CODE>
<P>Once unmounted, you can press the button on the front of the drive to
eject the cartridge.
<H2><A NAME="ss4.2">4.2 Repartitioned DOS Jaz Disks</A>
</H2>
<P>Since a Jaz disk is simply a disk, it can be repartitioned and reformatted
like a fixed disk. If this is done, you need to know which partition numbers
were used during repartitioning to be able to mount the disk.
<P>For instance, if the partition table was wiped, and a single new partition
was created as the first partition, the two mount commands from the previous
section would be:
<P><CODE>mount -t vfat /dev/sda1 /dos_jaz</CODE>
<P>and
<P><CODE>mount -t msdos /dev/sda1 /dos_jaz</CODE>
<H2><A NAME="ss4.3">4.3 Linux-Native Jaz Disks</A>
</H2>
<P>Linux-Native Jaz disks allow files to be stored with standard Unix
permissions and case-sensitive filenames. The only drawback to Linux-Native
disks is that they can no longer be used on DOS/Windows machines.
<P>A Jaz disk looks the same as a hard drive to Linux, so for those of you
familiar with the Linux disk management tools, none of the following will be
a surprise.
<P>
<P>If you want to erase a Jaz disk and make a Linux native file system on
it, you use fdisk on the entire disk. Please be very careful using fdisk,
especially if you have a SCSI hard drive - we wouldn't want to have any
"accidents". :-) In particular, make sure you are operating on the correct
device before making changes. In most cases, you'll use:
<P><CODE>fdisk /dev/sda</CODE>
<P>and delete the existing partitions (with the d command). Then create a new
partition with the n command, make it primary partition number 1 (using all
the cylinders), use w to write the partition table to disk, and quit with
q.
<P>Once the partition has been created, format it with:
<P><CODE>mke2fs /dev/sda1</CODE>
<P>(The 1 is the number that you gave this partition in fdisk). I prefer to
create a separate mount point for Linux native Jaz disks, and you'll see why
a little later when we talk about the <CODE>fstab</CODE>. So let's create that
mount point now, and then mount the disk:
<P><CODE>mkdir /jaz</CODE>
<P><CODE>mount -t ext2 /dev/sda1 /jaz</CODE>
<P>As usual, when the Jaz disk is mounted, it cannot be ejected. When you're
done using the Jaz disk, you unmount it with:
<P><CODE>umount /jaz</CODE>
<P>Once unmounted, you can press the button on the front of the drive to
eject the cartridge.
<H2><A NAME="ss4.4">4.4 Checking Linux-Native Jaz Disks</A>
</H2>
<P>Like your other disk drives, once a Linux Jaz disk has been mounted and
unmounted a certain number of times, the system will mark the disk as
"dirty". When this happens, you'll get a message like:
<P><CODE>Mounting unchecked filesystem, /dev/sda1. Recommend running e2fsck.</CODE>
<P>Once you see this message, it's a good idea to go ahead and check the disk.
The disk must be <EM>unmounted</EM> in order to check it. Unfortunately, you
only get the "dirty" message when you mount it, so you can either check the
disk when you're done using it, or unmount it, check it, then re-mount it.
Use the following command to check the disk (assuming the partition to be
checked is the first one):
<P><CODE>e2fsck /dev/sda1</CODE>
<H2><A NAME="ss4.5">4.5 Using the fstab to Make Things Easier</A>
</H2>
<P>Up to now, we've had to be root to mount and unmount the Jaz disks, and
we've had to type quite a bit to mount the Jaz disks. By adding a couple of
entries to the file <CODE>/etc/fstab</CODE>, we can make using the Jaz drive
<EM>much</EM> easier.
<H3>DOS Format Disks</H3>
<P>If you've got preformatted DOS disks, and you've created the
<CODE>/dos_jaz</CODE> mount point, you can add this line to the file
<CODE>/etc/fstab</CODE>:
<P><CODE>/dev/sda4 /dos_jaz vfat defaults,user,nosuid,noauto 0 0</CODE>
<P>With this line in the fstab, <EM>any user</EM> can mount and unmount a
DOS-format Jaz cartridge with the following commands:
<P><CODE>mount /dos_jaz</CODE>
<P><CODE>umount /dos_jaz</CODE>
<P>This is because we have told Linux what the Jaz device ID and media type
are in the <CODE>fstab</CODE>, plus we have given the <CODE>user</CODE> option to
allow any user to mount and unmount the disk. Naturally, if your Jaz drive
is other than <CODE>sda</CODE>, you'll need to change that, and this won't work
for DOS cartridges that have been repartitioned without another entry in
the fstab that uses a <EM>separate</EM> mount point (e.g. /dos_jaz2).
<H3>Linux Format Disks</H3>
<P>If you've got Linux formatted disks, and you've created the
<CODE>/jaz</CODE> mount point, you can add this line to the <CODE>fstab</CODE>:
<P><CODE>/dev/sda1 /jaz ext2 defaults,user,exec,nosuid,noauto 0 0</CODE>
<P>With this line in the fstab, <EM>any user</EM> can mount and unmount a
Linux-format Jaz cartridge with the following commands:
<P><CODE>mount /jaz</CODE>
<P><CODE>umount /jaz</CODE>
<P>Once again, we have told Linux what the Jaz device ID and media type are
in the <CODE>fstab</CODE>, plus we have given the <CODE>user</CODE> option to allow
any user to mount and unmount the disk. Some system administrators may not
wish to have the <CODE>exec</CODE> option present, as there are some security
risks with letting any user run an executable of unknown origin from the
drive, but with the <CODE>nosuid</CODE> option present, these risks are
minimal.
<H3>Automatic Mount at Boot Time</H3>
<P>Both of the <CODE>fstab</CODE> examples above have the option <CODE>noauto</CODE>
in them to prevent the disk from being automatically mounted at boot time.
In general, this is a good idea because if there is no disk in the drive
when the computer boots, or the drive is powered off, it can cause varying
amounts of trouble, depending on which SCSI driver you are using.
<P>If you're <EM>sure</EM> you want to mount the jaz drive at boot time,
simply remove the <CODE>noauto</CODE> option, and make sure the drive is on,
and a cartridge is inserted before booting. Note that you can only have
one fstab entry for jaz drive that will auto-mount, or you may encounter
the same problems as if there was no cartridge in the drive.
<H2><A NAME="ss4.6">4.6 The Jaz "tools" Disk</A>
</H2>
<P>With some Jaz drives, the software to run the drive is supplied on a
Jaz cartridge instead of on CD-ROM. The "problem" with these disks is that
software-controlled write protection is enabled on the disk, so that the user
can't wipe the disk until after the tools are installed at least once.
<P>There are several ways you can reclaim the Jaz tools disk:
<UL>
<LI>Install the tools on a DOS/Windows computer.</LI>
<LI>Use a DOS/Windows computer with the Jaz tools already installed to
remove the password protection.</LI>
<LI>Use one of the Linux Utilities mentioned in a later section to remove
the password protection.</LI>
</UL>
<P>If you have access to one of the password protection removal programs, all
you need is the password that Iomega uses, and it is:
<P><CODE>APlaceForYourStuff</CODE>
<P>Note that capitalization is important.
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