From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: Incredibly poor performance of mdraid-1 with 2 SSD Samsung 840 PRO Date: Mon, 22 Apr 2013 21:59:27 -0500 Message-ID: <5175F90F.6060206@hardwarefreak.com> References: <5171CBF9.9020701@redhost.ro> <51725458.7020109@redhost.ro> <51732422.1050109@redhost.ro> <5173536C.2040108@hardwarefreak.com> <51743F14.7020404@hardwarefreak.com> <517488B7.9030505@hardwarefreak.com> <21ba656fc34d77a018772f603ba5b75f@redhost.ro> Reply-To: stan@hardwarefreak.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Tommy Apel Cc: Andrei Banu , linux-raid Raid List-Id: linux-raid.ids On 4/22/2013 7:02 AM, Tommy Apel wrote: > Yes it can be run as it is, it will write to the file given by --filename= > > well from what I make of it so far I wouldn't rule out the bad device > part but at the same time there could be other things involved > although I don't belive it to be the md part > > Stan> do you know anything about the state of ext4 on centos 6.x ? Enough to assume it's not part of the problem here. Andrei's hdparm below the filesystem layer throughput is bouncing up/down by ~100MB/s depending on when he runs it. If he's using LVM and has active snapshots that would definitely cause some extra load, but in that case given his 3 RAID1 pairs it should affect both drives equally. And that's not what we're seeing. I hope my last post gets him closer to identifying the problem. The perf top and iotop data doing $bigfile copy should be instructive. -- Stan