[wellylug] High load averages but no apparent cause

[David Harrison]

Cheers Daniel.
Will do tonight out of hours.

I hope it isn't one of the drives, they are brand new and the servers in
Auckland whilst I am here in Wellington...


David


On Tue, Mar 23, 2010 at 9:20 AM, Daniel Reurich <daniel at centurion.net.nz>wrote:

> On Tue, 2010-03-23 at 08:50 +1300, David Harrison wrote:
> > Thanks Daniel that switch for vmstat is very handy and I'd completely
> > missed the io wait value in top.
> > Googling based on your comments also brought up this page which is
> > very handy:
> > http://strugglers.net/wiki/Linux_performance_tuning
> >
> >
> > The problem is certainly is looking like an intermittent I/O issue.
> >
> Probably caused by a disk issue - seriously.  I have seen this before.
> >
> > Has anyone experience with the performance boost of a dedicated PCI-X
> > SATA controller for software RAID?
>
> >
> > The server in question is a bog-standard HP ML110.
> > It isn't up to their needs, but it was a recent purchase by the
> > previous IT guys, so I'm afraid it is staying.
> >
> I don't think it should be an issue.
> >
> > For practical reasons I want to keep the software RAID-5 (3x1TB
> > drives), but would putting some (or all) of these disks onto a
> > dedicated controller alleviate the I/O issue?
> >
> I'd say it would provide none to minimal gain given your load stats if
> you are using software raid, and a small gain if you get hardware raid.
> >
> > i.e. Is it worth recommending a $400 PCI-X SATA controller for the
> > box, or is that money better left on the table for a new server
> > (ML310/330) in twelve months time?
> > (My concern being that the card goes in and the problem remains the
> > same.)
>
> Save the money unless you can be sure it's the built in controller (I
> doubt it is).
>
> I think your next port of call is to d a SMART check on your drives.
> Install smartmontools and do a smartctl -son /dev/sdX for each drive,
> and report that back if you don't understand the results.
>
> Regards,
>        Daniel.
>
>
>
>
>
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