Re: [Bacula-users] Copy Job performance issues

[Christoph L. <li...@un...>]

Am 07.12.2010 um 02:53 schrieb Dan Langille:

> On 12/6/2010 11:13 AM, Christoph Litauer wrote:
>> Dear bacula users,
>> 
>> I have a problem concerning the speed of copy jobs. My setup is:
>> - bacula server is OpenSuSE 11.3, version 5.0.3 using postgres, 2 Xeons (4 cores) and 8 GB memory.
>> - Attached is an iSCSI-RAID containing File devices
>> - Copy Jobs run to a Quantum Scalar 50 Tapelibrary with 2 LTO4 tape drives. The library and the tapes are connected via eSATA. According to wikipedia, LTO4 should transfer 120MB/s without compression. Compression is enabled.
>> 
>> My backups go to the iSCSI-RAID. I run CopyJObs every day to copy all uncopied jobs to tape.
>> My problem is, that my copy jobs run with max. 45 Mbyte/s
>> 
>> I checked the following:
>> - btape shows a maximum speed of 80MByte/sec.
>> - I can read about 150 Mbyte/s from the RAID device
>> - Copying data from RAID to tape using dd I get rates about 80 MByte/s
>> - While copying the cpu load is about 20-50% (bacula-sd)
>> 
>> So it seems as if bacula-sd itself slows the copy jobs down, but I cannot imagine, why. Maybe it is a configuration issue, but reading the manuals didn't help.
>> 
>> Configuration of the tape device in bacula-sd.conf:
>> 
>> Autochanger {
>>   Name = "Scalar50-2"
>>   Device = "LTO4-0"
>>   Device = "LTO4-1"
>>   Changer Device = /dev/tape/by-id/scsi-3500e09e0bb562001
>>   Changer Command = "/usr/lib64/bacula/mtx-changer %c %o %S %a %d"
>> }
>> 
>> Device {
>>   Name = "LTO4-0"
>>   Device Type = Tape;
>>   Media Type = LTO4
>>   Archive Device = /dev/tape/by-id/scsi-3500110a00104374e-nst
>>   AutomaticMount = yes;
>>   AlwaysOpen = yes;
>>   RemovableMedia = yes;
>>   RandomAccess = no;
>>   Autochanger = yes
>>   Drive Index = 0
>>   Spool Directory = /var/spool/bacula
>> }
>> 
>> Device {
>>   Name = "LTO4-1"
>>   Device Type = Tape;
>>   Media Type = LTO4
>>   Archive Device = /dev/tape/by-id/scsi-3500110a0012be1ee-nst
>>   AutomaticMount = yes;
>>   AlwaysOpen = yes;
>>   RemovableMedia = yes;
>>   RandomAccess = no;
>>   Autochanger = yes
>>   Drive Index = 1
>>   Spool Directory = /var/spool/bacula
>> }
>> 
>> Any ideas?
> 
> I'm guessing.
> 
> A copy job does a great deal of disk access.  It had to read all the 
> data from the Volume.  It has to read the original Catalog entries.  It 
> has to write the new Catalog entries.
> 
> 

Hi Dan,

thanks for your suggestions. I am just doing a very large copy job (about 600 GB):
- CPU load is 35-50% used by bacula-sd
- iostat gives me about 40-50 MB/s reading performance on my iSCSI-Device (which is able to read about 150MB/s).
- postmaster takes about 2% CPU load
- iowait is 0 to 0.2%

I can see no bottleneck at all ... but "status storage" still reports 40MB/s write performance.

--
Kind regards
Christoph
_________________________________________
Christoph Litauer
Uni Koblenz, Computing Centre, Office A 022    
Postfach 201602, 56016 Koblenz     
Fon: +49 261 287-1311, Fax: -100 1311