[OmniOS-discuss] areca or lsi

[Saso Kiselkov]

On 19/07/2013 03:05, David Bomba wrote:
> High quality RAID cards don't just perform simple passthrough, even thou
> we would expect this to be all that is needed in a ZFS implementation. 

I know that that's what *RAID* cards do, but I specifically try to avoid
RAID cards and go for simple HBAs. Hardware (and by that I also mean the
firmware running on it) should be as dumb/simple as possible, I want to
keep all of the complex logic in the software, which I can monitor
(DTrace), update and fix myself if necessary. I've had plenty of
performance issues on e.g. HP SmartArrays which just put a fat opaque
layer between you and the drives and then it's anybody's guess on why
the system's performance is sucking.

> The controller will (at least in Areca's case) utilise writeback caching
> to improve performance, driver implementation is also a major factor in
> performance. We've seen significant performance improvements with
> firmware upgrades on Areca cards.

Here you've reiterated my point on the trouble of diagnosing
performance. By simply swapping the driver you've seen "significant
performance improvements", so good luck getting the driver vendor to
optimize their driver if your customer is crying that performance is bad.

Cheers,
-- 
Saso