Tar and cpio

[Carter Jay]

Hello,

I 've got problems with Backup Tapes:
1 . How can I check what's on a tape (mt + tar||frecover||cpio????), and what's for you the best way to perform this?
2 . I've tried to put 2 tar archives on one tape, using for the first time:

#mt rew
#tar cvf - / | compress>/dev/rmt/c4t4d0BESTn
The second day, I used:
#mt rew \* To be sure*#mt eod \* To be sure*#tar cvf - / | compress>/dev/rmt/c4t4d0BESTn
Then , to look at what' on my tape:
#mt rew
#uncompressI had the first listing...Then
#mt fsf 1
#uncompressstdin: not in compressed format
Tar: blocksize = 0; broken pipe?
As if i was at the end of the second file and so it couldn't find a tar.

3 . How can I find the date a tar was created (using "uncompress
Could you help

Thanks in advance

Regards

Jerome

[H.Merijn Brand (procura · Accepted solution]

1. *NEVER* make backup's using an absolute path!

# cd /
# tar cvf - . | compress >/dev...

instead of

# tar cvf - / | com...

2. Don't use compress, but gzip. It's both more portable, and compresses much better

3. Use GNU tar (available on https://www.beepz.com/personal/merijn) which has builtin compression

# cd /
# gtar -czf /dev/rmt/c4t4d0BESTn .

4. To see what the tape format is, use 'dd' and 'file'

# cd /tmp
# dd if=/dev/rmt/0m ibs=102400 count=1 of=xx
# file xx

which might be hard to see if you use compress, gzip, or bzip2, because they might not be able to decompress the first block only :/

5. Ad 3. if / does not change (unlikely), it's time stamp has no info whatsoever to the date of the tape.

# cd /
# date >/tmp/stamp
# gtar -czf /dev/rmt/0m /tmp/stamp .

will put the file /tmp/stamp, with the current date, as first file on the tape, giving you a nice and fast indication of when the tape was created

I myself place an index as first file on the tape, so I don't have to read the complete tape to see what's on it. The index then also is my stamp. This is a two pass backup process, but proves to save a lot of time later on

HTH

[Chris Wilshaw]

What kind of tape drive are you using? Accorind to the mt man page

eod Seek to end of data (DDS and QIC drives only).

[Chris Wilshaw]

What kind of tape drive are you using? According to the mt man page

eod Seek to end of data (DDS and QIC drives only).

[Carter Jay]

Hello,

I'm using a DLT 8000 tape...

Thanks a lot for your help

Regards

Jerome