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 _______________________________________________ OmniOS-discuss mailing list OmniOS-discuss@lists.omniti.com http://lists.omniti.com/mailman/listinfo/omnios-discuss