On Tue, Nov 27, 2012 at 12:12:43PM +0000, Edward Ned Harvey 
(opensolarisisdeadlongliveopensolaris) wrote:
> > From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
> > boun...@opensolaris.org] On Behalf Of Eugen Leitl
> > 
> > can I make e.g. LSI SAS3442E
> > directly do SSD caching (it says something about CacheCade,
> > but I'm not sure it's an OS-side driver thing), as it
> > is supposed to boost IOPS? Unlikely shot, but probably
> > somebody here would know.
> Depending on the type of work you will be doing, the best performance thing 
> you could do is to disable zil (zfs set sync=disabled) and use SSD's for 
> cache.  But don't go *crazy* adding SSD's for cache, because they still have 
> some in-memory footprint.  If you have 8G of ram and 80G SSD's, maybe just 
> use one of them for cache, and let the other 3 do absolutely nothing.  Better 
> yet, make your OS on a pair of SSD mirror, then use pair of HDD mirror for 
> storagepool, and one SSD for cache.  Then you have one SSD unused, which you 
> could optionally add as dedicated log device to your storagepool.  There are 
> specific situations where it's ok or not ok to disable zil - look around and 
> ask here if you have any confusion about it.  
> Don't do redundancy in hardware.  Let ZFS handle it.

Thanks. I'll try doing that, and see how it works out.
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