[CentOS] OT: Caching synchronous writes

Thu Apr 22 20:41:53 UTC 2010
Ray Van Dolson <rayvd at bludgeon.org>

On Thu, Apr 22, 2010 at 03:37:41PM -0500, Les Mikesell wrote:
> On 4/22/2010 3:20 PM, Ray Van Dolson wrote:
> > [ Wish there was a generic, active Linux "storage" mailing list out
> >    there -- something other than the kernel lists I mean ]
> >
> > To frame the discussion, we use VMware ESX (vSphere) quite a bit with
> > NFS datastores.  Often times with NetApp, but lately, more often with
> > Solaris 10 + ZFS + SSD's for ZIL (intent log or write cache).
> >
> > The ZIL lets us use synchronous writes (safer) without the normal
> > delay.  Were we to try and get the same level of performance with
> > Linux, we'd need to use async mode for our NFS shares -- and we'd lose
> > some reliability.
> >
> > However, given the latest rumblings and ruminations about Oracle
> > potentially no longer selling entitlements for Solaris 10 on non-Sun
> > hardware -- and then turning around and no longer allowing you to run
> > Solaris 10 "freely", we're left with either OpenSolaris or looking at
> > Linux again (we run Solaris 10 on Silicon Mechanics hardware).
> Is there some problem with OpenSolaris or NexentaStor?

Maybe not, but am trying to see what options there are on the Linux

The "delayed allocation" features in ext4 (and xfs, reiser4) sound
interesting.  Might give a little performance boost for synchronous
write workloads....

[ We like Nexenta and OpenSolaris just fine, but really like the
  stability guarantee Solaris gives us -- much like RHEL.  Would rather
  not have to worry (as much) about needing to reboot storage boxes and
  even though I have confidence in OpenSolaris, it's still more of a
  moving / changing target.  Not to say we won't ultimately go in that
  direction though. ]