From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Breidenbach Subject: Re: Multiplexed RAID-1 mode Date: Mon, 1 Aug 2005 02:09:20 -0400 Message-ID: References: <200507311907.WAA07886@raad.intranet> <17133.41835.683675.621675@cse.unsw.edu.au> Reply-To: jeff@jab.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <17133.41835.683675.621675@cse.unsw.edu.au> Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Al Boldi , Gordon Henderson , linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi Neil, Are you suggesting I do this? mdadm --create /dev/md0 --level=10 --raid-devices=2 \ --parity=f2 /dev/sdc1 /dev/sdd1 I just tried it and it appears dog slow - for example hdparm -t /dev/md0 claims 18MB/s, and I see a similar number in /proc/mdstat for resync speed. Getting rid of the --parity=f2 parameter, the numbers jump up to about 65MB/s which is similar to single drive transfer rate. Anyway, I haven't thoroughly benchmarked and I know hdparm is not to be trusted, but so far it's not obvious to me level=10 beats level=1 for a two drive array. If you think it is worth pursuing I will do so. Cheers, Jeff PS. I care most about small (~5K) file read performance. Think very busy webserver with hundreds of gigabytes of small files. And an occasional medium size file of a few megabytes.