From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Landmann Subject: Re: RAID 5 doesn't scale Date: Wed, 3 Apr 2013 21:19:52 +0000 (UTC) Message-ID: References: <515C2C3C.3020400@hardwarefreak.com> <515C73B3.5060704@arcor.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids > I'm very sorry but now i can't confirm anymore that stripe_cache_size helps. > > My test was to short. With every minute the IOPS decrease. So > stripe_cache_size does only help for very short tests. > > I will provide details in another post. > Now i wish i could delete the post. As the SSD performance decrease with running time (within minutes) i'm not sure if the better performance with higher stripe_cache_size would be constant over time or is more a effect from a fresh empty cache that ceases with time (in my scenario with writing many small random blocks) Short tests results: Raid 5, 3 SSD stripe_cache_size noop deadline (tuned) 256 18914 18730 16384 18161 19766 Raid 5, 4 SSD stripe_cache_size noop deadline (tuned) 256 11863 13716 16384 13186 14688 Peter