Bootable Tape for Redhat 7.3

I'm a Linux hack, learning as I go based on a machine or two in our company.

This is probably really elementary for you pros.  I have a Redhat 7.3 box with a tape drive attached.  I would like to make a backup tape that I could use to boot the system in case of emergency or hardware issue.  I've been googling and tried a few methods, but haven't had any success.

As an alternative - it does have a cdrw attached to it as well.

Thanks in advanced.
Matt HastenSecurity AnalystAsked:
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joolsConnect With a Mentor Commented:
check out the man page of tar, it mentions a blocking option of N*512 bytes, the default is 20.

try `tar czf /dev/st0 -b 64 /Cache`

you can experiment with different block sizes, may want to test with a smaller directory first :-)
also, the z option compresses, if the tape drive compresses the data automatically then it may well add a bit of overhead. I think there is a tapeinfo (needs mtx package) command, or is it mt -f <device> status, I don't use tape myself, I find it easier to backup to disk.

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balasundaram_sCommented:
Hardware & BIOS should support booting from Tape apart from RedHat.  And RedHat kernel has to be modified to support, creating boot image on Tape.  I dont think so, its worth the efforts.
Boot from CD and restore from Tape would be the best option, as it looks like.
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Jon BrelieSystem ArchitectCommented:
Assuming you are using dump/restore to create the tapes, I would use a generic Linux boot CD and use MT commands and dump/restore to write data from tape back to disk.  WAY faster than booting from tape.  

Is there a specific reason you want to do it from tape?
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Matt HastenSecurity AnalystAuthor Commented:
Not really (on the tape specifically). Could one of you guys spell out the steps for making the data backup and a boot cd?
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Jon BrelieSystem ArchitectCommented:
how to use dump / restore to backup/restore your system:  http://www.nethamilton.net/docs/dump.html

Any generic linux distro boot cd should have MT and dump.
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joolsCommented:
Use knoppix to boot up, make sure you can see your tape drive on the SCSI controller.
If you have RH 7.3 then dont use dump, there were posts about dump having bugs, RH 7.3 is really really old!!! Use cpio or tar to backup, do not backup /proc (I don't think /sys is on RH7.3!) I seem to remember /dev is not covered by udev so make sure this is backed up, it shouldnt cause problems).

Boot from knoppix CD/DVD.

Create your filesystem areas for root etc etc.

Mount the filesystems under /newroot (or whatever you want).

Restore from tape to /newroot.

Customise the /newroot/etc/fstab and the boot loader (could be lilo!!!).

TaDa!
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Matt HastenSecurity AnalystAuthor Commented:
Am looking at the cpio command now. Dump isn't an option, it isn't installed (unrecognized command).  I tried a few tar backups, but I cannot confirm that the directory I need backed up is really backed up. There really is only one data directory that I need backed up - this is a 'dumb' storage server - and all the data I need is in one directroy.
I'm a bit worried about rebooting before backing up. I'm getting a nebulous hardware warning light and the only way to get the diagnosis is rebooting (error logs are stored in ROM, accessible during bootup, per the IBM documentation).  Well, you know how it goes - the server may only still be running because it hasn't been rebooted.
I've got approximmately 97GB to get backed up. The tape drive specs say that with the tapes I have in my possession it will back up 80GB native and 160GB compressed.
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joolsCommented:
Example backup commands;

cd /
find . | cpio -ocvC65536 > /dev/rmt0

cd /
tar czvf /dev/rmt0 .

The man pages offer loads of options for each command, there is no point if pasting here, just run man <command>.

What make / model tape drive are you using? You may be able to tweak the block size to get better thruput, there is a tape guy somewhere on EE who knows all the block sizes that can be used.
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Matt HastenSecurity AnalystAuthor Commented:
The tape drive is a Exabyte VXA 2 - thanks for your help thus far. I'm much further along than I was.
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Matt HastenSecurity AnalystAuthor Commented:
well - here's what I tried, which looked as though it was working, but then after nearly 6 hours, failed.
tar -csf /dev/st0 /Cache (Cache being the directory I want)
Like I mentioned, it ran for nearly 6 hours, but then returned this:
tar (child): //dev/st0: Wrote only 0 of 10240 bytes
tar (child): Error is not recoverable: exiting now
Broken pipe

Any ideas of what that means specifically?
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Matt HastenSecurity AnalystAuthor Commented:
sorry, the ta command I used was:
tar -czf /dev/st0 /Cache

I put 's' instead of 'z' in the previous message.
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