topic Re: Backups on tape in Operating System - Linux

Backups on tape

Alfonso_4 — Wed, 19 Dec 2001 01:59:24 GMT

Hi, I need to backup a lot of information on tapes. I need to use more than one tape on each backup so I used tar -M (multi-volume)and dump -M, but it doesn't seems to work very well. Because when tar ask me the next tape and I insert it, tar send me this error message: "tar: Error is not recoverable: exiting now"

Could you recommend me another software to backup or the right way to backup with tar or dump with multi-volume option?
Thank you.
I will appreciate any help.

Re: Backups on tape

Francois Bariselle_3 — Wed, 19 Dec 2001 19:49:08 GMT

hey,

You can use fbackup command :

fbackup -0i / -f /dev/rmt/0mn
(For all host file system)

fbackup -0i / -e -e -f /dev/rmt/0mn
(For selected data)
ex.:

fbackup -0i / -e /tbdat -e /tbsys -e /dbs -e /tbsys_u2 -f /dev/rmt/0mn

You can use with sam!

Good luck.

Frank

Re: Backups on tape

G. Vrijhoeven — Wed, 19 Dec 2001 20:05:06 GMT

Hi,

fbackup / sam are UX tools with linux version / tar version are you using?

you could create a shel script that figures out the ammount of data that is in the file systems you try to backup (
A=0
for i in `df -vk | grep -v used | awk '{print $3)'`
do
let A="$A ++ $1"
echo $A
done

should show the ammount of disk space used.
combine it with the ammount of data you can put on tape and start a partial backup.

Hope this will help,

Gideon

Re: Backups on tape

Mark Fenton — Wed, 19 Dec 2001 22:14:06 GMT

Other questions -- could you use tar with the z option to gnu-zip the backups also? How big are the tapes, how many gigs are you moving, etc.?

just a thought.

Re: Backups on tape

Jairo Campana — Thu, 20 Dec 2001 13:29:20 GMT

I use cpio

cd /tmp
find . |cpio -ocv < /dev/
o
find /home |cpio -ocv < /dev/

cpio -ocv /home < /dev/

whit -C he establishes the size in blocks of E/S

Re: Backups on tape

Alfonso_4 — Thu, 20 Dec 2001 20:14:39 GMT

Thank you all for your help, but what I need is a software that let me backup on more than one tape on LINUX, like tar -m. I tried to use tar again, but it isn't very reliable. Fbackup seems a good option but it doesn't work on linux. CPIO supports multi-volume?

Re: Backups on tape

Paulo A G Fessel — Thu, 20 Dec 2001 20:57:51 GMT

Provided that you're using ext2, you can use the "dump" and "restore" utilities, as they will ask for a new tape whenever it's necessary to perform the backup. For example, to make a level 0 dump of the / filesystem to /dev/rmt0n you would do:

dump -0 -f /dev/rmt0n /

To perform an interactive restore, you use...

restore -i -f /dev/rmt0n

Dump/restore are filsesystem specific; that is, you can't use dump/restore in a ReiserFS filesystem. If you're using XFS, it features xfsdump/xfsrestore. I don't know how JFS manages filesystem dumps.

Hope it helps,

Paulo Fessel

Re: Backups on tape

Kodjo Agbenu — Thu, 20 Dec 2001 23:39:41 GMT

Hello,

The best way to achieve what you want is to use a real backup software, instead of "tar" or "cpio" (standard unix archiving software).

In OpenSource products, you can read the documentation of "amanda" (I don't know how to use it, but I've heard that it is a good product).

In commercial products, I would suggest ARKEIA that is normally free for a very limited number of clients.

Of course, both software handle multi-volume. They can also backup over the network to another machine (client/server).

Another trick : if the -M option of the "tar" command is not reliable, it may be due to the variable size of your data. I guess (but I'm not sure) at the end of the tape, the last data block sometimes could be truncated and in that case the tar would return and error.

To avoid that, you can force the tar to request another tape when it reaches a pre-defined size, by using the "-L" option.

For example if you use a DDS3 device with 125m tapes and compression, the mean amount data that could be theoretically stored is 24 GB. Then, you may use "-L" to limit this size to 20 GB, to force the "tar" command requesting another tape before reaching the end-of-tape.

I guess the "-L" should be combined with "-M", but I haven't tested this.

Good luck.

Kodjo