On Tue, Sep 17, 2013 at 9:53 AM, Andreas Koch <
k...@esa.informatik.tu-darmstadt.de> wrote:
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> Hello Kern,
>
> the problem is not so much the risk of errors, but that btape (and
> correspondingly, Bacula) fails even the simplest of readback tests with
> block sizes above 128KB. dd works perfectly well with multi-megabyte
> blocks,
> both reading and writing.
>
> Here's the info I previously collected:
>
> btape cannot reliably handle anything larger than 128 KB (fails on reading,
> see below).
>
> However, when I read (using dd) the tape that btape supposedly has written
> _two_ files of 10000 blocks each (and then fails after reading 3616 of
> them!), dd reads read _each_ of btape-written 10000-block ``files'' as
> _three_ separate actual tape files (of 3616+3616+2768=10000 blocks). Note
> that this specific test was performed with a block size of 512KB (see
> Device
> definition from bacula-sd.conf, below).
>
> So, this might actually be a Bacula-specific problem after all. We see this
> behavior consistently on two different HP LTO-5 drives, on two different
> SAS
> HBAs (one using mpt2sas as driver, the other one with mvsas), and using two
> different SAS cables.
>
> If you need additional info, please let me know how to proceed.
>
> Many thanks in advance,
> Andreas
>
>
> *** TRY BTAPE TEST, WILL FAIL ON READBACK
>
> gundabad ~ # btape -c /etc/bacula/bacula-sd.conf /dev/nst0
> Tape block granularity is 1024 bytes.
> btape: butil.c:290 Using device: "/dev/nst0" for writing.
> btape: btape.c:477 open device "LTO-4" (/dev/nst0): OK
> *test
>
> === Write, rewind, and re-read test ===
>
> I'm going to write 10000 records and an EOF
> then write 10000 records and an EOF, then rewind,
> and re-read the data to verify that it is correct.
>
> This is an *essential* feature ...
>
> btape: btape.c:1157 Wrote 10000 blocks of 524188 bytes.
> btape: btape.c:609 Wrote 1 EOF to "LTO-4" (/dev/nst0)
> btape: btape.c:1173 Wrote 10000 blocks of 524188 bytes.
> btape: btape.c:609 Wrote 1 EOF to "LTO-4" (/dev/nst0)
> btape: btape.c:1215 Rewind OK.
> Got EOF on tape.
>
Hmm. Isn't 512K 524288 bytes not 524188 bytes? Could that be the problem?
John
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