[Nottingham] What's on top?

[Andy Davidson]

On Mon, Apr 17, 2006 at 05:08:28PM +0100, Martin wrote:
 > (So I guess 55.7% wa is rather bad after all... :-( )

Maybe, maybe not - if you're running a very intensive disk-bound process
during an otherwise idle period, then I wouldn't bother spending any 
money or effort 'fixing' it.

If this is your general server's state and you need your application to
respond less in a less 'spongy' manner, then at least you now know how
to fix the issue; 

 - is your server swapping like mad ?  Buy more memory if so.
 - is disk on its way out ?  does hdparm -tT indicate seriously
   substandard performance ?  replace if so !
 - buy good quality disks.  if ide, investigate sata or scsi.
 - consider quality controller, e.g. 3-Ware sata 9500S
 - profile the behaviour - is it mainly reads ?  mainly writes ?
 - if reads, will raid mirroring help ?  if controller supports
   readahead will it help ?
 - if writes, will raid 5 help ?
 - if this is your application will an in-memory cache help ?  is it
   actually your cacheing which is destroying disk performance ?

I am sure others will respond with more ideas.


Good luck !

cheers
-a