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Re: [Bacula-devel] MaximumBlockSize Problem and Question


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 maybe documentation just a little outdated.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? 

-- Pasi

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