backup and compression

[Primary]

Is there a way to compress information before backing it up to tape and uncompressing it when restoring using ufsdump/restore, cpio, or tar? Currently I'm using ufsdump, and it is fine, but the amount of data that needs to be backed up is increasing. If there isn't a way to do this, is there a good recommendation on software or hardware that would be a good choice?
I need to back up just over 20 Gigs of data, and am using an Exabyte 20/40 tape drive. It seems that the tape drive should be able to handle it, but it doesn't seem so as I keep getting messages to replace the tape when it hits the end, so I'm guessing that the info isn't being compressed. Anyway, any advice would be very appreciated. Thanks!

 

[mikeclark]

I have used cpio to backup data. A DDS-3 tape holds 12Gb or 24Gb compressed.
(depending on the type of files ) I have backed up 22 Gb using this.
To back up a directory:
cd to the directory
find . -depth -print | cpio -ocmv > /dev/rmt/0

to restore:
cd to required directory
cpio -icv < /dev/rmt/0

(to restore only some files cpio -icv &quot;file pattern&quot; < /dev/rmt/0 )
Note: The tape device will have to match your device.

 

[cgswong]

By specifying the device as /dev/rmt/0c you will turn compression on for the device. The 'c' at the end of the device (/dev/rmt/0) turns on compression for the device. This should be all you need as compressing then backing up would increase your backup time.

Regards.

- Stuart

 

[mikeclark]

You're right Stuart,
the one small detail I missed out on was the &quot;c&quot;

 

[Primary]

Thanks very much. I put that c on there and I'm getting everything on the tape now. Thanks! I was confused because the man page on ufsdump said that putting c as an option meant that the backup media was cartridge and so the end-of-tape was computed differently, but it didn't lead me to believe that it was a large change.
Anyway, it works so I'm not complaining! Thanks again for your help!

 

[jad]

i was under the misguided (?) opinion that the default for a drive _was_ compressed

i've checked my logs and the amount i get on my tape is within the 'compressed' tape size and over the 'non-compressed' size.

could just be sony drivers, oh - and hp, but i think that it defaults to on.

if there is a /dev/rmt/0l then you can probably turn it off.

just my 2 cents.

Jon