raid 10 su, sw settings

[Brad Langhorst <brad@langhorst.com>]

I have this system
 - 3ware 9650 controller
 - 4 disk raid 10
 - 64k stripe size
 - this is a vmware host, so lots of r/w on a few big files.

I'm not entirely satisfied with its performance.

Typical blocks/sec from iostat during large file movements is about
100M/s read and 80M/s write.

When I set this up, I did not fully understand all the details... so I
want to check a few things.

 - is the partition aligned correctly? i fear not...
        /dev/sda1   *           1          24      192748+  83  Linux
        /dev/sda2              25       19449   156031312+  83  Linux
        
        Is this where I'm losing performance?
 
 - What should the sunit and swidth settings be during mount?
        I guess with raid 10 the width is 2 so...
        sunit = 128 (64k/512) and swidth = 256 (2*64k/512)
        
        Or maybe I should use width 1 ?
        
        Remounting (mount -o remount) with these options does not lead
        to a noticeable change in performance. Must I recreate the fs or
        unmount and remount?

Here's the output of xfsinfo in case it's relevant.

xfs_info  /
meta-data=/dev/sda2              isize=256    agcount=16, agsize=2437989
blks
         =                       sectsz=512   attr=0
data     =                       bsize=4096   blocks=39007824,
imaxpct=25
         =                       sunit=0      swidth=0 blks, unwritten=1
naming   =version 2              bsize=4096  
log      =internal               bsize=4096   blocks=19046, version=1
         =                       sectsz=512   sunit=0 blks
realtime =none                   extsz=65536  blocks=0, rtextents=0