[CentOS] OT: Caching synchronous writes

[Ray Van Dolson]

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
side.

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. ]

Thanks,
Ray