From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: make filesystem failed while the capacity of raid5 is big than 16TB Date: Wed, 19 Sep 2012 11:00:42 -0500 Message-ID: <5059EC2A.7070407@hardwarefreak.com> References: <505033fe.8aec440a.5d52.ffffe37b@mx.google.com> <50504094.2040302@hesbynett.no> <505059DD.8000108@hesbynett.no> <5051DEC3.9050703@hardwarefreak.com> <50584B75.1060606@hesbynett.no> <5058E9DF.6090007@hardwarefreak.com> <5059722D.1070409@hesbynett.no> Reply-To: stan@hardwarefreak.com Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5059722D.1070409@hesbynett.no> Sender: linux-raid-owner@vger.kernel.org To: David Brown Cc: GuoZhong Han , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 9/19/2012 2:20 AM, David Brown wrote: > On 18/09/2012 23:38, Stan Hoeppner wrote: >> Actually, no. The level of parallelism is the same--30 concurrent >> writes. As noted above, the increase in performance comes from locating >> each of the AGs on a different disk, or array. This decreases the >> number of seeks requires per write, especially with parity arrays. > OK, so you get 30 parallel logical writes, but if it does not translate > into multiple parallel physical writes to the disks by having multiple > member disks, then the gains are small. The problem in the OP's case isn't a lack of physical write parallelism, but most likely a problem of seek starvation caused by write parallelism. -- Stan