|Summary:||Cannot restore multivolume cpio tape backups|
|Product:||[Retired] Red Hat Linux||Reporter:||giulioo|
|Component:||kernel||Assignee:||Michael K. Johnson <johnsonm>|
|Status:||CLOSED NOTABUG||QA Contact:|
|Fixed In Version:||Doc Type:||Bug Fix|
|Doc Text:||Story Points:||---|
|Last Closed:||2000-01-31 09:26:59 UTC||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Cloudforms Team:||---||Target Upstream Version:|
Description giulioo 1999-09-01 07:42:05 UTC
PROBLEM: I can do multivolume cpio backups on tape, but then I cannot restore them due to cpio problems. SETUP: cpio-2.4.2-12 kernel 2.2.12; scsi_mod, aha152x, st as modules (it happened with rh6 stock 2.2.5 too) SCSI controller: Adaptec AVA-1050 SCSI tape unit: Tandberg SLR2 525MB DETAILS: I use these commands: Backup: find /path|cpio -ovHcrc -O /dev/st0 - it starts to backup then it asks me for a 2nd tape with: "Found end of tape. Load next tape and press RETURN." I insert the 2nd tape and the backups ends regularly with the message about the blocks copied. Restore: cpio -ivdumHcrc -I /dev/st0 - it asks me for the 2nd tape with: "Found end of tape. Load next tape and press RETURN." - then asks me for a 3rd tape!!, with: "Found end of tape. Load next tape and press RETURN." Since I have not a 3rd tape (the backup took 2 tapes only), I simply press enter (_leaving_ the 2nd tape IN) "cpio: read error: No medium found" (the 2nd tape is in). Note that: - The stuf restored is only 5/10k smaller than the original size, very little but the restore is unreliable. - the backup took very little of the 2nd tape (say 10MB). - I even tried with -B 5120 - I tried with different tapes (3M), different controllers (all ISA adaptec with module aha152x.o) and different tape units (all Tandberg) I found an article on dejanews regarding problems with cpio multivolume restore with kernels 2.0.x (cpio quits as soon as it arrives at the end of the 1st tape with an I/O error). I found nothing regarding kernels 2.2.x. ===begin deja article on 2.0.x kernels On Tue, Mar 24, 1998 at 11:26:10AM +0100, Stephane KLEIN wrote: > But the restoring (cpio -i ..) fails at the end of the first tape with a > read IO error. I think this is a known bug in 2.0.X. The following message is from Kai Mdkisara, maintainer of the SCSI tape driver: | On Wed, 28 May 1997, Jan Echternach wrote: | > There is a problem with taper not detecting the end of tape. With my | > SCSI DAT drive and kernel 2.0.30, read() returns 0 only one time, and | > all subsequent reads return EIO. It seems that ftape returns _two_ | > times 0, which taper handles correctly. | > | ... | > | > Do 2.1.x kernels return two times 0? If so, should 2.0.30 also return | > two times 0 at end of tape? | > | What should happen, according to the BSD semantics, is this: | - at filemark, the first read returns 0 bytes, the second read returns | data from the next file | - at EOD, the first and the second read return 0 bytes, the third returns | error (-1) | i.e., 2.1.x operates correctly. | | The EOD behaviour was fixed at 2.1.20. In principle, it should be fixed | also at 2.0.31 but I think the risks are too big: fixing EOD behaviour | may break something else (the fix from 2.1.20 can't be used directly). | | Kai ===end deja article
Comment 1 Jeff Johnson 1999-12-17 18:46:59 UTC
This appears to be a kernel problem (although the fix may have to be in cpio) so I'm changing the component to kernel ...
Comment 2 giulioo 2000-01-31 09:26:59 UTC
I contacted Kai Makisara (st driver author). He told me the problem seems to be my scsi drives (all tandberg TDC 41xx) that have problems with writing and reporting the status of the tape when the end of the tape is reached. The solution, that works for me, is to disable async and buffer writes for the st driver: mt stclearoption async-writes mt stclearoption buffer-writes This options are disabled by default on other unix (dg-ux, interactive) so that I had the problem on linux only.