From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brad Campbell Subject: Re: mismatch_cnt constantly goes up on ssd+hdd raid1 Date: Thu, 25 Jun 2015 13:30:25 +0800 Message-ID: <558B91F1.4090709@fnarfbargle.com> References: <3700381434301996@web21o.yandex.ru> <20150625113335.7bf72b0b@noble> <20150625101959.23981c72@natsu> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150625101959.23981c72@natsu> Sender: linux-raid-owner@vger.kernel.org To: Roman Mamedov , NeilBrown Cc: tlknv , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 25/06/15 13:19, Roman Mamedov wrote: > Couldn't this be simply the normal observed effect of using TRIM on SSD? > After deleting some files, the filesystem issues a discard request, it > does nothing to the HDDs, but the content of the discared areas on SSD is no > longer deterministic (or mostly zeroed, as mentioned in the original report). > So there is now a mismatch between the content of HDDs and SSD, but since it > is in the area of deleted files, it doesn't affect the system in any way. > I get this on a RAID10 with Intel & Samsung SSD's. One supports deterministic after TRIM and the other doesn't. Mismatch count is always through the roof as a result but there are no other negative effects.