Hi,
On 1/9/2006 9:49 PM, Chris Hunter wrote:
Some questions:
i) Can you please post your bacula-sd.conf & bacula-dir.conf settings
for LTO drives (especially HP Ultrium-1 drives) plus additional st
options ?
Even though I don't operate any LTO drives here - you should supply the
versions of Bacula used and OS details. Otherwise, most of what other
people might send will not be very useful for you.
Thanks for your reply,
I am using bacula 1.38.2 which I compiled from source. I am using
Scientific Linux 4.2, which similar to CentOS, is built on rhel4 source
binaries.
Ok, so this looks more or less like a standard setup without any
difficulties to expect.
I have had partial sucess with the "btape fill command". I issued the
follwing mt commands before starting btape:
mt -f /dev/nst1 rewind
mt -f /dev/nst1 stoptions buffer-writes async-writes read-ahead
Hmm. buffer-writes is not usually on (with my kerel and according to the
relevant documentation (Documentation/scsi/st.txt in the source tree) it
sounds as though it should not be necessary normally. Quite contrary, I
understand, because in variable block mode (what Bacula prefers) it can
become a performance-consuming process under the wrong circumstances.
mt -f /dev/nst1 defblksize 0
If the above is actually the reason for our problem, you might try
loading the st driver/module with options. buffer_kbs and
write_threshold_kbs might be a start, but you should read st.txt
yourself - I might be totally wrong.
Using these commands, I can run "btape fill" without errors. It writes
~105GB to tape in 20hrs...that's less then 2mb/s ! I think the transfer
rate should be closer to 15Mbyte/s.
That would be more reasonable, indeed.
Note that btape thinks the rate is ~1500KB/s (ie 15MB/s).
Erm, really? I might be confused, but I calculate 1500 times kilo to
equal 1.5 mega. But I don't think this actually matters here.
But the drive
spends most of its time idle:
Ok, that's more interesting. Have you checked with ps or top if the
machine is busy doing other things, or if btape is waiting for something?
Wrote blk_block=5000, dev_blk_num=4999 VolBytes=322,495,472 rate=1528.4
KB/s
Wrote blk_block=10000, dev_blk_num=9999 VolBytes=645,055,424
rate=1532.2
KB/s
Wrote blk_block=15000, dev_blk_num=14999 VolBytes=967,615,368
rate=1531.0 KB/s
I don't know the reasons, but I suspect there is definitely something
wrong - the data transfer is much too slow for a LTO device. 1.5
MBytes/second is really too slow. LTO-1 should write with much higher
speeds.
I suspect a SCSI problem, something like faulty termination, wrong
cables and resulting slower transfers than possible, or a too high
simultaneous use of the SCSI bus, for example because you've got your
disks attached to it, too.
The autochanger is the only device on the scsi bus. Next step will be
test termination & lvd cables :(
As long as you can be sure that's not a problem resulting from a heavily
loaded system, that would be the next step... but have you checked what
the OS says about the SCSI subsystem?
Arno
--
IT-Service Lehmann [EMAIL PROTECTED]
Arno Lehmann http://www.its-lehmann.de
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