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Re: [Bacula-devel] MaximumBlockSize Problem and Question


On Thu, 2008-12-04 at 20:03 +0200, Pasi Kärkkäinen wrote:
> On Wed, Nov 05, 2008 at 02:48:20PM +0100, Ulrich Leodolter wrote:
> > On Wed, 2008-11-05 at 13:34 +0200, Pasi Kärkkäinen wrote:
> > > On Wed, Nov 05, 2008 at 11:12:01AM +0100, Ulrich Leodolter wrote:
> > > > Hello,
> > > > 
> > > > Problem:
> > > > 
> > > > Settings like (documented in the Manual)
> > > > 
> > > >      Minimum block size = 64K
> > > >      Maximum block size = 200K
> > > > 
> > > > do not work. Both are defined as size_pint32.
> > > > multipliers like K M are not allowed.
> > > > don't know if this is intended, 
> > > > maybe documentation just a little outdated.
> > > > 
> > > > 
> > > > Question:
> > > > 
> > > > Can i expect performance improvements (especially for
> > > > Copy/Migrate Disk to Tape jobs) by by increasing
> > > > "Maximum block size" on File devices in bacula-sd.conf ???
> > > > 
> > > > Device {
> > > >   Name = FileStorage
> > > >   Media Type = File
> > > >   Archive Device = /disk0/bacula/files
> > > >   LabelMedia = yes;  
> > > >   Random Access = Yes;
> > > >   Requires Mount = No;
> > > >   AutomaticMount = yes;
> > > >   RemovableMedia = no;
> > > >   AlwaysOpen = no;
> > > >   MaximumBlockSize = 1048576;         # 1M
> > > > }
> > > > 
> > > 
> > > I think it should make difference at least with tape drives.. 
> > > 
> > > You can measure the difference with dd:
> > > 
> > > dd if=/dev/null of=/dev/tape bs=<try_different_block_sizes_here>
> > > 
> > > 4k, 64k, 256k, 1MB, 4MB etc.
> > 
> > Hello,
> > 
> > I dont think raw performance is bad, as u can see below
> > (exeption is 4k block size on tape,
> >  hopfully bacula does not use it :-)
> > 
> > Maybe i should set
> > 
> > 	Minimum Block Size = 4194304
> > 
> > on both devices (Tape, File)
> > This should reduce the number of block read/writes communication
> > by a factor of 64.
> > 
> > Will try it tonight,  unless u give me a very good hint how to
> > optimize ;-)
> > 
> 
> Hi!
> 
> Did you figure out 'best' performance settings for these disk-to-tape copy jobs? 
> 

Hi,

still using default tape block size 63k

disk volumes are limited to 4G

concurrent disk backup jobs use spooling, now full backup jobs
are spread almost continuous over 4G volumes

copy disk to tape runs without spooling at rates up to 50000 kbytes/s


this is acceptable, but emc networker does the same job (copy disk
backup jobs to tape) at rates up to 75000 kbytes/s


but there is still an open bug which affects performance
http://bugs.bacula.org/view.php?id=1190
especially when concurrent disk backup dont use spooling.



Regards
Ulrich


> -- Pasi
> 


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