On May 27, 2009, at 8:34 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:

On Tue, May 26, 2009 at 01:00:21PM -0700, Christopher Smith wrote:
> > > On a related note, does anyone know of any work being done to
> > facilitate cache synchronization/mirroring between two machines and
> > allow for enterprise-SAN-esque redundant controllers with writeback ?
> >
> > Are you familiar with the DRBD project ?
>
> Yes, but it doesn't really do what I'm talking about.
>
> I want something that will let me setup a pair of IETD "heads" that can have mirrored cache, so I can DIY an iSCSI SAN with full redundancy *and still have write-back caching*.
>
> Ie: equivalent functionality to a dual-controller MD3000i, Equallogic PS6000 series, etc, but using something like a pair of Dell R610s in front of some MD1000 JBODs.
>

Indeed, IETD cache sync between hosts would be cool. I'm familiar with Equallogic arrays and it seems to work well there
between controllers.

Wondering if 10 Gbit Ethernet would still have too high latency for cache
sync between IETD hosts?

Well you could try using DRBD between two hosts with SSD disks and dm-cache, but building such functionality into IET is impractical.

-Ross


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