Disk IO issues

[Ramez Hanna]

On Sun, Jan 4, 2009 at 7:59 PM, Mike McGrath <mmcgrath at redhat.com> wrote:

> On Sat, 3 Jan 2009, Matt Domsch wrote:
>
> > On Sun, Jan 04, 2009 at 03:02:55AM +0000, Kostas Georgiou wrote:
> > > On Sat, Jan 03, 2009 at 06:32:38PM -0600, Matt Domsch wrote:
> > >
> > > > What ext3 journaling options are enabled (e.g. what does 'mount'
> say)?
> > > > If it's data=ordered (the default), that's OK.  If it's data=journal,
> > > > then all the data gets written twice (first to the journal, then the
> > > > journal to the disk), which is really really slow, and the size of
> the
> > > > journal would really make a difference too.
> > >
> > > For an NFS server (assuming that you aren't exporting as async)
> > > data=journal can give you better performance than anything else
> > > actually. The NFS howto has a brief note in the performance section
> > > about this.
> >
> > Yes, if the slowness is seen by applications on the client side of the
> > NFS server, data=journal on the NFS server can help.
> >
> > Mike, your tests were all on the local file system, not across an NFS
> > connection, right?
> >
>
> Correct, though (obviously) we're seeing the slownees remotely as well.
>
>        -Mike
>
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Hi,

I've had no previous experience with such issues but here are my 2 cents
IMHO if the slowness is seen locally as well as remotely then i would start
thinking about filesystem options, or even consider a different filesystem.
I think that you need to eliminate first the HW issues (raid, disk speed,
etc) then look more into fs specific options wich were discussed in several
previous emails
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