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Unix Cpio / tar large files Backup

Iain Hamilton_4
Occasional Contributor

Unix Cpio / tar large files Backup

I am trying to back up files using cpio or tar to a 20/40Gb DLT from a Sco Unix server. When i backup small files it seems ok but stops on files over 50Mb. I am backing up using
cpio -ivdumB -I/dev/rmt/ctape1
then reading using
cpio -itv -I/dev/rmt/ctape1
Do i have to specify block size and if so what should it be? or what should tar command be?
I am therefore I think????
6 REPLIES
Leif Halvarsson_2
Honored Contributor

Re: Unix Cpio / tar large files Backup

Hi,
I am not familar with SCO unix but I think the tar command is similar to other Unix
try: tar cvf /dev/rmt/ctape1

There is filesize limitations in some versions of tar and cpio but this usually is 2GB, not 50MB.
Caesar_3
Esteemed Contributor

Re: Unix Cpio / tar large files Backup

Hello!

Try to switch into the linux mode on SCO
"linux" command and see if you command will work.
Try the tar command, if you have SCO 7 or 8
(should came with new tar version)
than it backup much more large files.

Caesar
Iain Hamilton_4
Occasional Contributor

Re: Unix Cpio / tar large files Backup

Thanks - I tried

Tar cvf /dev/rmt/ctape1 /u01/exports/CHEST

Seemed to write to tape ok

When I try to retrieve:

tar xvf /dev/rmt/ctape1 /u01/exports/CHEST

starts to retrieve then get error message
UX:tar: ERROR: Directory checksum error


x /u01/exports/CHEST/, 0 bytes, 0 tape blocks
x /u01/exports/CHEST/CHEST_log.Wed, 53770 bytes, 106 tape blocks
x /u01/exports/CHEST/CHEST_exp.Wed.Z, 58857362 bytes, 114956 tape blocks
x /u01/exports/CHEST/CHEST_log.Wed.Z, 8512 bytes, 17 tape blocks

UX:tar: ERROR: Directory checksum error
I am therefore I think????
Anthony Guzzi
Occasional Visitor

Re: Unix Cpio / tar large files Backup

This may sound like a silly thing to mention,
but to make sure all bases are covered, have you a) cleaned the tape drive recently and b) have you tried using different
tapes?

I bring this up because a checksum error on an extraction could point to either dirty heads in the tape drives (resulting in data being corrupted when read) or surface issues with the tape (resulting in the data not being properly written in the first place). Remember that the checksum in the TAR header for each file is generated bases on the file's contents as read from disk. At extraction time, the checksum is regenerated based on the data read from the tape and compared with the value in the file's header. So if the drive heads are dirty or the tape is "damaged", the files contents will be different (they'll have errors) and as such the checksum at extraction time will differ from that generated when the tape was created.

If you have cleaned the drives, try using the 'i' option (ignore checksum errors) to see if you can read past the error. If you can, I'd mark the tape as bad and not use it again.
Michael Steele_2
Honored Contributor

Re: Unix Cpio / tar large files Backup

To backup with CPIO

cd /dir
find . | cpio -oBx /dev/rmt/ctape1

To verify and read tape with CPIO

cpi -itB < /dev/rmt/ctape1

To restore with CPIO:

cpio -idumvB < /dev/rmt/ctape1

To selectively restore with CPIO

cpio -idumvB "pattern with pathway" < /dev/rmt/ctape1

Note that files > 2gb will not be backed up. So here is GNU tar and GNU cpio for SCO which will back up files > 2gb:

http://www.sco.com/skunkware/COMPONENTS.html
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Michael Steele_2
Honored Contributor

Re: Unix Cpio / tar large files Backup

Ooops, typo:

To backup with CPIO

cd /dir
find . | cpio -oBx > /dev/rmt/ctape1
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