From: Jan-Olaf Droese (jan-olaf.droese@lahmeyer.de)
Date: Thu Oct 31 2002 - 12:43:10 EST
Dear sun-managers,
we are currently trying to upgrade our tape libraries (Spectralogic
S10000) to AIT3.
The problem is that we are unable to read tapes written with a fixed
blocksize of 256k on the AIT2 drives with the new AIT3 drives. This
means that we can't read old tapes written with our backup software
(Alexandria 4.50.68). Writing tapes without a specific blocksize on
a AIT2 drive with tar and reading them back in an AIT3 drive works
fine.
To narrow down the cause of the problem we did the tests described
below which just use dd. The essence of the tests is: What comes a
out as one full block of data from an AIT2 drive comes as five
partial blocks from the AIT3 drive. I think this is what confuses
Alexandria.
Does anyone have any idea how to solve the problem? Maybe some
additional flags in st.conf?
We tried to get support from various sources but so far the only
solution is keeping one of the old AIT2 drives to read the old
tapes.
OS is Solaris 2.7 Generic_106541-14.
Thanks for your help I will summarise.
Jan-Olaf
Tests carried out:
- put a tape written with Alexandria in a AIT2 drive and read the
tape header with dd. Alexandria uses a fixed block size of 256k
This gives the following results:
bash# dd if=/dev/rmt/2cbn bs=256k of=test.ait2
1+0 records in
1+0 records out
(the tape header only is one block, so the result is as expected)
- put the same tape in a AIT3 drive and read the tape header:
bash# dd if=/dev/rmt/3cbn bs=256k of=test.ait3
0+5 records in
0+5 records out
Both output files test.ait2 and test.ait3 are identical, but
the AIT3 drive does not give one full block with 256k of data
but 5 partial blocks back to the application.
When reading larger files from the tape (more than one 256k block)
the behaviour remains the same. AIT2 returns N full blocks an no
partials, AIT3 returns 0 full blocks and 5*N partials.
Maybe this change of behaviour when reading tapes with a fixed
blocksize is the reason why we are unable to read old tapes with
Alexandria.
We can read tapes written with tar to a AIT2 drive without a specified
block size fine in the AIT3 drive.
The AIT2 tapes are written with the following st.conf:
tape-config-list="SONY SDX-500C", "Sony AIT 8mm", "SONY_TAPE";
SONY_TAPE = 1, 0x34, 0, 0x1639, 4, 0x13, 0x8c, 0x8c, 0x8c, 3;
For AIT3 we tried both
tape-config-list="SONY SDX-700C", "Sony AIT3 8mm", "SONY_AIT";
SONY_AIT = 1, 0x34, 0, 0x3d639, 1, 0x30, 0;
and
tape-config-list="SONY SDX-700C", "Sony AIT3 8mm", "SONY_TAPE";
SONY_TAPE = 1, 0x34, 0, 0x1639, 4, 0x13, 0x8c, 0x8c, 0x8c, 3;
-- Jan-Olaf Droese | Lahmeyer International GmbH email: jan-olaf.droese@lahmeyer.de | Friedberger Stra_e 173 phone: +49-6101-55-1611 | 61118 Bad Vilbel fax: +49-6101-55-1623 | Germany _______________________________________________ sunmanagers mailing list sunmanagers@sunmanagers.org http://www.sunmanagers.org/mailman/listinfo/sunmanagers
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