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320 lines
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<TITLE>HOWTO: Multi Disk System Tuning: Other Operating Systems</TITLE>
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<LINK HREF="Multi-Disk-HOWTO-8.html" REL=next>
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<LINK HREF="Multi-Disk-HOWTO-6.html" REL=previous>
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<LINK HREF="Multi-Disk-HOWTO.html#toc7" REL=contents>
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<A HREF="Multi-Disk-HOWTO-8.html">Next</A>
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<A HREF="Multi-Disk-HOWTO.html#toc7">Contents</A>
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<HR>
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<H2><A NAME="s7">7. Other Operating Systems</A></H2>
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<P>
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disk!operating systems, other
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Many Linux users have several operating systems installed, often
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necessitated by hardware setup systems that run under other operating
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systems, typically DOS or some flavour of Windows. A small section on
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how best to deal with this is therefore included here.
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<P>
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<H2><A NAME="ss7.1">7.1 DOS</A>
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</H2>
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<P>
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disk!operating systems, other!DOS
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Leaving aside the debate on weather or not DOS qualifies as an operating
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system one can in general say that it has little sophistication with
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respect to disk operations. The more important result of this is that there
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can be severe difficulties in running various versions of DOS on large
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drives, and you are therefore strongly recommended in reading the
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<EM>Large Drives mini-HOWTO</EM>. One effect is that you are often better
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off placing DOS on low track numbers.
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<P>Having been designed for small drives it has a rather unsophisticated
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file system (<CODE>fat</CODE>) which when used on large drives will allocate
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enormous block sizes. It is also prone to block fragmentation which
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will after a while cause excessive seeks and slow effective transfers.
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<P>One solution to this is to use a defragmentation program regularly but
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it is strongly recommended to back up data and verify the disk before
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defragmenting. All versions of DOS have <CODE>chkdsk</CODE> that can do some
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disk checking, newer versions also have <CODE>scandisk</CODE> which is somewhat
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better. There are many defragmentation programs available, some versions
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have one called <CODE>defrag</CODE>. Norton Utilities have a large suite of
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disk tools and there are many others available too.
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<P>As always there are snags, and this particular snake in our drive
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paradise is called <EM>hidden files</EM>. Some vendors started to use
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these for copy protection schemes and would not take kindly to being
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moved to a different place on the drive, even if it remained in the
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same place in the directory structure. The result of this was that
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newer defragmentation programs will not touch any hidden file, which
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in turn reduces the effect of defragmentation.
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<P>Being a single tasking, single threading and single most other things
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operating system there is very little gains in using multiple drives
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unless you use a drive controller with built in RAID support of some
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kind.
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<P>There are a few utilities called <CODE>join</CODE> and <CODE>subst</CODE> which
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can do some multiple drive configuration but there is very little
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gains for a lot of work. Some of these commands have been removed in
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newer versions.
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<P>In the end there is very little you can do, but not all hope is lost.
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Many programs need fast, temporary storage, and the better behaved
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ones will look for environment variables called <CODE>TMPDIR</CODE> or
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<CODE>TEMPDIR</CODE> which you can set to point to another drive. This is
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often best done in <CODE>autoexec.bat</CODE>.
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<P>
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<HR>
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<PRE>
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SET TMPDIR=E:/TMP
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SET TEMPDIR=E:/TEMP
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</PRE>
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<HR>
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<P>Not only will this possibly gain you some speed but also it can
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reduce fragmentation.
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<P>There have been reports about difficulties in removing multiple primary
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partitions using the <CODE>fdisk</CODE> program that comes with DOS. Should this
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happen you can instead use a Linux rescue disk with Linux <CODE>fdisk</CODE> to
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repair the system.
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<P>Don't forget there are other alternatives to DOS, the most well known
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being
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<A HREF="http://www.caldera.com/dos/">DR-DOS</A>
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from
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<A HREF="http://www.caldera.com/">Caldera</A>.
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This is a direct descendant from DR-DOS from Digital Research.
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It offers many features not found in the more common DOS, such
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as multi tasking and long filenames.
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<P>Another alternative which also is free is
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<A HREF="http://www.freedos.org/">Free DOS</A>
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which is a project under development. A number of free utilities
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are also available.
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<P>
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<P>
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<P>
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<H2><A NAME="ss7.2">7.2 Windows</A>
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</H2>
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<P>
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disk!operating systems, other!Windows
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Most of the above points are valid for Windows too, with the exception
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of Windows95 which apparently has better disk handling, which will get
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better performance out of SCSI drives.
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<P>A useful thing is the introduction of long filenames, to read these from
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Linux you will need the <CODE>vfat</CODE> file system for mounting these partitions.
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<P>
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<P>Disk fragmentation is still a problem. Some of this can be avoided by
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doing a defragmentation immediately before and immediately after installing
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large programs or systems. I use this scheme at work and have found it
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to work quite well. Purging unused files and emptying the waste basket first
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can improve defragmentation further.
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<P>Windows also use swap drives, redirecting this to another drive can give
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you some performance gains. There are several mini-HOWTOs telling you how
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best to share swap space between various operating systems.
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<P>
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<P>
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<P>
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<P>The trick of setting <CODE>TEMPDIR</CODE> can still be used but not all
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programs will honour this setting. Some do, though. To get a good
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overview of the settings in the control files you can run <CODE>sysedit</CODE>
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which will open a number of files for editing, one of which is the
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<CODE>autoexec</CODE> file where you can add the <CODE>TEMPDIR</CODE> settings.
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<P>Much of the temporary files are located in the <CODE>/windows/temp</CODE>
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directory and changing this is more tricky. To achieve this you can
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use <CODE>regedit</CODE> which is rather powerful and quite capable of
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rendering your system in a state you will not enjoy, or more
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precisely, in a state much less enjoyable than windows in general.
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Registry database error is a message that means seriously bad news.
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Also you will see that many programs have their own private temporary
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directories scattered around the system.
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<P>Setting the swap file to a separate partition is a better idea and much
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less risky. Keep in mind that this partition cannot be used for anything
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else, even if there should appear to be space left there.
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<P>It is now possible to read <CODE>ext2fs</CODE> partitions from Windows,
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either by mounting the partition using
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<A HREF="http://www.yipton.demon.co.uk/">FSDEXT2</A>
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or by using a file explorer like tool called
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<A HREF="http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm">Explore2fs</A>.
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<P>
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<P>
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<H2><A NAME="ss7.3">7.3 OS/2</A>
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</H2>
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<P>
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The only special note here is that you can get file system driver for
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OS/2 that can read an <CODE>ext2fs</CODE> partition.
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Matthieu Willm's ext2fs Installable File System for OS/2 can be found at
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<A HREF="ftp://ftp-os2.nmsu.edu/pub/os2/system/drivers/filesys/ext2_240.zip">ftp-os2.nmsu.edu</A>,
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<A HREF="ftp://sunsite.unc.edu/pub/Linux/system/filesystems/ext2/ext2_240.zip">Sunsite</A>,
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<A HREF="ftp://ftp.leo.org/pub/comp/os/os2/drivers/ifs/ext2_240.zip">ftp.leo.org</A> and
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<A HREF="ftp://ftp-os2.cdrom.com/pub/os2/diskutil/ext2_240.zip">ftp-os2.cdrom.com</A>.
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<P>The IFS has read and write capabilities.
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<P>
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<P>
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<H2><A NAME="ss7.4">7.4 NT</A>
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</H2>
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<P>
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disk!Microsoft!bug
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This is a more serious system featuring most buzzwords known to marketing.
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It is well worth noting that it features software striping and other more
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sophisticated setups. Check out the drive manager in the control panel.
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I do not have easy access to NT, more details on this can take a bit of time.
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<P>One important snag was recently reported by acahalan at cs.uml.edu :
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(reformatted from a Usenet News posting)
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<P>NT DiskManager has a serious bug that can corrupt your disk when you have
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several (more than one?) extended partitions. Microsoft provides an
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emergency fix program at their web site. See the
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<A HREF="http://www.microsoft.com/kb/">knowledge base</A>
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for more. (This affects Linux users, because Linux users have extra partitions)
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<P>You can now read <CODE>ext2fs</CODE> partitions from NT using
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<A HREF="http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm">Explore2fs</A>.
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<P>
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<P>
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<H2><A NAME="ss7.5">7.5 Windows 2000</A>
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</H2>
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<P>
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disk!operating systems, other!Windows 2000
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Most points regarding Windows NT also applies to its descendant Windows 2000
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though at the time of writing this I do not know if the aforementioned bugs
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have been fixed or not.
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<P>While Windows 2000, like its predecessor, features RAID, at least one
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company,
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<A HREF="http://www.raidtoolbox.com/">RAID Toolbox</A>,
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has found the bundled RAID somewhat lacking and made their own commercial
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alternative.
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<P>
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<P>
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<H2><A NAME="ss7.6">7.6 Sun OS</A>
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</H2>
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<P>
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disk!operating systems, other!SunOS
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There is a little bit of confusion in this area between Sun OS vs. Solaris.
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Strictly speaking Solaris is just Sun OS 5.x packaged with Openwindows and
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a few other things. If you run Solaris, just type <CODE>uname -a</CODE> to see your
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version. Parts of the reason for this confusion is that Sun Microsystems
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used to use an OS from the BSD family, albeight with a few bits and pieces
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from elsewhere as well as things made by themselves. This was the situation
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up to Sun OS 4.x.y when they did a "strategic roadmap decision" and decided
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to switch over to the official Unix, System V, Release 4 (aka SVR5),
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and Sun OS 5 was created.
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This made a lot of people unhappy. Also this was bundled with other things
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and marketed under the name Solaris, which currently stands at release
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7 which just recently replaced version 2.6 as the latest and greatest.
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In spite of the large jump in version number this is actually a minor
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technical upgrade but a giant leap for marketing.
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<P>
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<P>
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<P>
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<H3>Sun OS 4</H3>
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<P>
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disk!operating systems, other!SunOS 4
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This is quite familiar to most Linux users.
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The last release is 4.1.4 plus various patches.
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Note however that the file system
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structure is quite different and does not conform to FSSTND so any planning
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must be based on the traditional structure. You can get some information by
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the man page on this: <CODE>man hier</CODE>. This is, like most man pages, rather brief
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but should give you a good start. If you are still confused by the structure
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it will at least be at a higher level.
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<P>
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<H3>Sun OS 5 (aka Solaris)</H3>
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<P>
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disk!operating systems, other!Solaris
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This comes with a snazzy installation system that runs under Openwindows, it
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will help you in partitioning and formatting the drives before installing the
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system from CD-ROM. It will also fail if your drive setup is too far out, and
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as it takes a complete installation run from a full CD-ROM in a 1x only drive
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this failure will dawn on you after too long time. That is the experience we
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had where I used to work. Instead we installed everything onto one drive and then
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moved directories across.
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<P>The default settings are sensible for most things, yet there remains a little
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oddity: swap drives. Even though the official manual recommends multiple swap
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drives (which are used in a similar fashion as on Linux) the default is to use
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only a single drive. It is recommended to change this as soon as possible.
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<P>Sun OS 5 offers also a file system especially designed for temporary files,
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<CODE>tmpfs</CODE>. It offers significant speed improvements over <CODE>ufs</CODE> but does
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not survive rebooting.
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<P>
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<P>The only comment so far is: beware! Under Solaris 2.0 it seem that
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creating too big files in <CODE>/tmp</CODE> can cause an out of swap space
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kernel panic trap. As the evidence of what has happened is as lost as
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any data on a RAMdisk after powering down it can be hard to find out
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what has happened. What is worse, it seems that user space processes
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can cause this kernel panic and unless this problem is taken care of
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it is best not to use <CODE>tmpfs</CODE> in potentially hostile environments.
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<P>Also see the notes on
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<A HREF="Multi-Disk-HOWTO-5.html#tmpfs">tmpfs</A>.
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<P>Trivia: There is a movie also called Solaris, a science fiction movie that is
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very, very long, slow and incomprehensible. This was often pointed out at the
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time Solaris (the OS) appeared...
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<P>
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<P>
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<H2><A NAME="ss7.7">7.7 BeOS</A>
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</H2>
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<P>
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This operating system is one of the more recent one to arrive
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and it features a file system that has some database like features.
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<P>There is a BFS file system driver being developed for Linux
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and is available in alpha stage. For more information check the
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<A HREF="http://hp.vector.co.jp/authors/VA008030/bfs/">Linux BFS page</A>
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where patches also are available.
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<P>
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<P>
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<P>
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<HR>
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<A HREF="Multi-Disk-HOWTO-8.html">Next</A>
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<A HREF="Multi-Disk-HOWTO-6.html">Previous</A>
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<A HREF="Multi-Disk-HOWTO.html#toc7">Contents</A>
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