realy bad network performance with PowerEdge T610

William Warren hescominsoon at emmanuelcomputerconsulting.com
Mon Feb 21 17:17:43 CST 2011


On 2/21/2011 3:41 PM, Michael Zoet wrote:
>
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> Hi Blake,
>
> Am 21.02.2011 17:21, schrieb Blake Hudson:
> > The SAS2008 cards have no
> cache, while linux softraid will use
>
> > system RAM as a write cache by default. Additionally, most
> 'desktop
>
> > class' hardware does not honor fsync (commit to disk)
> requests and
>
> > operates in a forced write-back mode. I'm guessing this
> difference
>
> > in behavior is causing the high disk activity as well as IO
> wait you
>
> > are experiencing on the Dell. Applications that issue
> frequent
>
> > fsyncs (commits) will suffer noticeably because of this.
>
> >
>
> > The Dell hardware options you have chosen will write data
> to the
>
> > disks 'safely', while the previous HW configuration
> probably favored
>
> > speed over data integrity. If you want to go back to speed,
> you can
>
> > reconfigure the disks as single drives and go back to Linux
>
> > soft-raid. You may also be able to disable fsyncs in your
> NFS
>
> > exports. Another option is to use a HW RAID controller with
> battery
>
> > backed cache in write-back mode - like the PERC5/6 or
> H700/800 cards
>
> > - these would enable fast operation while maintaining data
> integrity.
>
> >
>
> > Mount/Export options with 'sync' will honor disk commits
> and write
>
> > to disk safely; 'async' options will prefer speed, but may
> result in
>
> > data corruption in the event of system crash/power loss.
>
> Thx for the explanation. Learning by experience... Next time I double
> check this. Never thought of buying a system for more than 2.000,- €
> to have a RAID controller with NO battery installed. Are the
> controller cards H700/800 or Perc5/6 compatible with the H200? I do
> not want to reinstall the whole system. Or I have to test my backups.
>
> Thx again,
>
> Michael
>
>
>
>
>
>
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Always test your backups irregardless.  You aren't going to be able to 
drop in h7x for the h2 without a reinstall IIRC.
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