From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brad Campbell Subject: Re: RAID performance Date: Thu, 07 Feb 2013 20:01:29 +0800 Message-ID: <51139799.2070004@fnarfbargle.com> References: <51134E43.7090508@websitemanagers.com.au> <51137FB8.6060003@websitemanagers.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51137FB8.6060003@websitemanagers.com.au> Sender: linux-raid-owner@vger.kernel.org To: Adam Goryachev Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 07/02/13 18:19, Adam Goryachev wrote: > problem. Is there some way to instruct the disk (overnight) to TRIM the > extra blank space, and do whatever it needs to tidy things up? Perhaps > this would help, at least first thing in the morning if it isn't enough > to get through the day. Potentially I could add a 6th SSD, reduce the > partition size across all of them, just so there is more blank space to > get through a full day worth of writes? I have 6 SSD's in a RAID10, and with 3.7.x (I forget which x - 2 or 3 from memory) md will pass the TRIM down to the underlying devices (at least for RAID10 and from memory 1). I have a cronjob that runs at midnight : #!/bin/sh export TIME="%E real\n%U user\n%S sys\n" for i in / /home /raid10 ; do /usr/bin/time /home/brad/bin/fstrim -v $i done Based on the run times, and the bytes trimmed count I suspect it works. All filesystems are ext4. Two of them are passed through encryption, but that passes TRIM down also. I do not have the discard option on any mounts (that way lies severe performance issues). Regards, Brad