Hello,
02.12.2009 07:23, Jens Froehlich wrote:
> Arno Lehmann schrieb:
>> Hello,
>>
>> and welcome!
>>
>> 30.11.2009 13:21, Jens Froehlich wrote:
>>> Hi bacula-users,
>>>
>>> I has a problem with my Bacula (3.0.2) installation on OpenSuSE 11.1
>>> (32Bit). The LTO-1 tapes are described only a half, nevertheless, it
>>> should fit 100 GB on it?
>> Depending on the data, yes. Usually, with compression enabled, you'd
>> get more than 100G on each tape.
>>
>>> I already succeed different values of the
>>> parametres " minimum block size" and "maximum blocksize" tested,
>>> unfortunately. If I the tapes with tar describe I reach 100 GB. I also
>>> find the writing speed with 6 MB/S a little bit slow?
>> Have you run the btape 'test' procedure?
>>
>> Do you see any SCSI-related messages in the system's log file?
>>
>> And yes, 6MB/s is rather slow for LTO-1, but the bottleneck could be
>> elsewhere.
>>
>> To get good speed, you need to do a bit of performance tuning, but
>> let's see the answers for the above questions first :-)
>>
>> By the way - I believe Kern will mention performance tuning on his
>> upcoming webinar. A link to regsiter is at
>> http://www.baculasystems.com/eng I don't know what he'll present in
>> detail, though...
>>
>> Cheers,
>>
>> Arno
>>
>
> - I used new Sony data cardriges with 100/200 GB
Good.
> - the drive hardwarecompression ist on
Good.
> - no SCSI errors are to be seen in the log files
Good.
> - test under Ubuntu 9.10 (server) with bacula 2.2.4 brought the same results
Not bad, though it doesn't give new information :-)
> - I have done different tests for the analysis.
Very good.
> - Basically everything seems to be, nevertheless, in order?
Yes.
>
> Tape Drive - test with the HP Test tool
> - Device Performance Test Started on Drive (Ultrium 1-SCSI)
> (0.4.0[0-/dev/sg0])
> - Opening Tape Drive 0.4.0[0-/dev/sg0]
> - Successfully opened the Tape Drive /dev/nst0
> - 2147 MB written in 33.6762 seconds at 63.7687 MB/s
That's reasonable throughput, and the LTTE program seems to be quite
reliable.
>
> hdparm (Hardware RAID5 with SATA Drives)
> /dev/sdc1:
> Timing cached reads: 1234 MB in 2.00 seconds = 616.73 MB/sec
> Timing buffered disk reads: 512 MB in 3.01 seconds = 170.11 MB/sec
This doesn't tell us the sustained data rate when doing real file
accesses, but it looks quite good.
dd'ing a big file to /dev/null will give results factoring in all the
higher-level environment, too.
> - the backup reads only from sdc1 (5-10 Gb Files)
That should be a data set that can be backed up quite speedily.
>
> write Test with dd
> dd if=/dev/zero of=/dev/nst0 bs=1M count=1000
> 1000+0 Datensätze ein
> 1000+0 Datensätze aus
> 1048576000 Bytes (1,0 GB) kopiert, 16,3772 s, 64,0 MB/s
Dumping zeros to a tape drive with compression doesn't tell us much.
You can prepare a big file of /dev/urandom data, and use that. Or use
a more recent (i.e., git HEAD) version of btape - that has some speed
tests integrated.
> btape
>
> *test
...
Looks all very good.
I would try dd'ing some random data to tape next.
Running sar or, at least, vmstat and top during testing and a slow
backup might reveal some unexpected bottlenecks.
Also, it's important to see where the backups are slow - for example,
the actual data transfer can be fast, and the catalog operations slow.
You can see some of that in the job report mail. (That wouldn't be too
uncommon, as catalog operations can vary in speed quite a lot,
depending on which database you use, and how that database is tuned.)
Cheers,
Arno
> Jens
>
>
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--
Arno Lehmann
IT-Service Lehmann
Sandstr. 6, 49080 Osnabrück
www.its-lehmann.de
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