Hi Andreas,
thank you for the swift answer.
I did try backing up to file storage, both on ZFS and UFS. Restoring from
this worked absolutely fine.
This is my device resource for the tape drive:
Device {
Name = "Ultrium"
Always Open = yes
Archive Device = "/dev/nsa0"
Auto Changer = no
Automatic Mount = yes
Block Checksum = yes
Block Positioning = yes
BSF at EOM = yes
Backward Space File = yes
Backward Space Record = yes
Device Type = Tape
Fast Forward Space File = yes
Forward Space File = yes
Forward Space Record = yes
Hardware End of File = yes
Hardware End of Medium = yes
Label Media = no
Maximum Block Size = 1048576
Maximum File Size = 32G
Maximum Spool Size = 256G
Media Type = "LTO"
Minimum Block Size = 65536
Offline On Unmount = no
Spool Directory = "/mnt/appdata/bareos/spool"
TWO EOF = yes
Use Mtiocget = yes
}
As I was not able to reproduce the problem with files, I tried to narrow
the problem down when restoring from tape and I came to notice something
odd. Backing up files, that just write a relatively small amount of data to
the tape (a few hundred MiB), works just fine. I tried it at least 20
times. However when I get to about 900 MiB and above total backup size, I
get the described checksum mismatch errors. It does not matter if it is a
single large 900 MiB file or several smaller files. As long as the overall
number of bytes written to the tape exeeds about 900 MiB, it faults when
restoring.
Unfortunately this is the reason why I can't dump you the files, as I
probably cannot upload a Gigabyte worth of files (correct me if I am
mistaken).
I wonder if there are any limitations by the operating system, that I don't
know of.
I hope, that we can get to the bottom of this.
Thank you very much for helping me, I appreciate it.
Best Regards,
Benedict Ecker
Andreas Rogge schrieb am Donnerstag, 15. Dezember 2022 um 12:30:14 UTC+1:
> Hi Benedict,
>
> Am 13.12.22 um 16:34 schrieb Benedict Ecker (Bene):
> > However when I am starting a restore job, I encounter problems. The
> > operation aborts with the error message "Volume data error! Block
> > checksum mismatch!".
>
> Thats bad. And - unless you wrote your tapes with a version affected by
> Bug #1180 - shouldn't happen. Even if you had been hit that Bug, it
> should still work if you read and write with the same version (it would
> miscalculate the checksum on write and on read, so it would still match).
> We currently don't do automated testing with FreeBSD on a real tape
> drive, so there might still be some kind of stange bug you've
> encountered here.
>
> However, the block checksum calculation happens before the data is
> handed off to the device-specific storage backend. So if there is some
> kind of problem, you should also see the same behaviour when backing up
> to files.
> Did you already try that?
>
> In any case, I would love to take a look at the device resource you
> configured in the SD.
>
> If you can reproduce the problem with files (which I doubt, as this is
> automatically tested during CI), could you provide a sample volume file
> (with just two or three files backed up?
>
> If you cannot reproduce the problem with files and it only happens with
> tape, would you run a small job (again, just two or three files) to a
> fresh or recycled tape, dump the tape-files and send them to me?
>
> To dump the tape files you can just mt rewind the tape and then
>
> dd if=/dev/your-drive of=file-0 bs=<your-blocksize>
> dd if=/dev/your-drive of=file-1 bs=<your-blocksize>
> ...
> dd if=/dev/your-drive of=file-N bs=<your-blocksize>
>
> until there is no more files to read (probably there will be just two -
> the label block and the backup session)
>
> I really hope we can sort this one out.
>
> Best Regards,
> Andreas
>
> --
> Andreas Rogge [email protected]
> Bareos GmbH & Co. KG Phone: +49 221-630693-86 <+49%20221%2063069386>
> http://www.bareos.com
>
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