Re: mkfs.xfs questions

[Christian Kujau <lists@xxxxxxxxxxxxxxx>]

On Wed, 29 Nov 2006, Jasmin Buchert wrote:
> Is there any real advantage of making the log size 32-64 MB and

From 'man mkfs.xfs':

   If the  log  is  contained within the data section and size isn't
   specified, mkfs.xfs will try to select a suitable log
   size depending on the size of the filesystem.  The actual
   logsize depends on the filesystem block size and the directory
   block size.

   Otherwise, the size suboption is only needed if the log
   section of the filesystem should occupy less space than the size
   of the special file.

So, if you're not limited by very special space restrictions, you won't 
need the "size" option.

> what is the difference between log version 1 and 2 regarding to
> efficency/performance?

The "version" option should have no effect on performance, from 'man 
mkfs.xfs' again:

     Using the version suboption to specify a version 2 log enables the
     sunit  suboption,  and  allows  the  logbsize  to  be increased
     beyond  32K.

The "sunit" options can be tweaked to provide better performace in raid5 
environments, same for the "agcount" option: for special needs only but 
I'm not aware of any benchmarks for different sunit/agcount values.

> Is it true that a small agcount is better for most systems
> (Gentoo and some other sources recommend this)? It's a desktop machine.

Hm, some people are indeed suggesting this [0], you might ask the author 
of the doc why he's doing this or test this by yourself.

Christian.

[0] 
http://www.rootforum.de/wiki/howto/gentoo/basesystem#formatieren_der_partitionen
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