> 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.

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