it seems that bacula's limit is "<= 4000000"
from src/stored/block.c :
> if (block_len > 4000000) {
> Dmsg3(20, "Dump block %s 0x%x blocksize too big %u\n", msg, b,
> block_len);
> return;
> }
another limit i found is this one from the output of "dmesg | grep st" :
> [ 3.695203] st0: Block limits 1 - 8388608 bytes.
> [ 3.697814] st1: Block limits 1 - 8388608 bytes.
Am 20.09.2013 16:01, schrieb Andreas Koch:
> On 09/20/2013 03:43 PM, Alan Brown wrote:
> > On 20/09/13 13:22, Andreas Koch wrote:
> >>
> >> Many thanks for the data point! When we use Bacula (not just btape)
> >> with larger block sizes (512 KB), our backups abort when bacula fails
> >> to read the tape's header block.
> >>
>
> > Did you attempt to mix blocksizes on the same physical tape?
>
> No. I initially tried writing with 512 KB to our existing tapes for
> differentials (that were written on LTO-4 drives onto the same tapes, also
> with 512 KB).
>
> > That will not work. If you change block sizes all existing tapes holding
> > data must be marked "used" and new ones labelled.
>
> That was my second attempt: Freshly labelled tapes. All tries with 512KB
> failed as described previously, only 128 KB succeeded.
>
> As with btape, the problem with the larger block sizes did not come up
> during writing, but during reading. This lead to all backups failing, since
> Bacula appears to read the on-tape header block before writing the actual
> backup.
>
> > I run 2Mb block size quite happily on HP LTO5 drives and have done for a
> > few years. They are capable of 16Mb - we are limited to 2Mb by Bacula.
>
> Hmm, curiouser and curiouser! I'll wait and see whether btape gets fixed to
> accept the larger block sizes and then proceed to run more tests.
>
> Many thanks for all the feedback!
>
> Best,
> Andreas
--
[:O]###[O:]
Besser man könnte da langfahren wo man nicht muss, als wenn man wo langfahren
muss wo man nicht
kann.
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