From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Segitz Subject: Re: Performance of a software raid 5 Date: Tue, 21 Apr 2009 04:04:09 +0200 Message-ID: References: <49ED096E.1000002@anonymous.org.uk> <49ED18E6.1090301@anonymous.org.uk> <15c92f8bd27d912e292c013fea2467e4.squirrel@neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <15c92f8bd27d912e292c013fea2467e4.squirrel@neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tue, Apr 21, 2009 at 3:19 AM, NeilBrown wrote: > Have you done any testing without the crypto layer to see what effect > that has? > > Can I suggest: > > =A0for d in /dev/sd[gjk]1 /dev/md6 /dev/mapper/data bigfile > =A0do > =A0 =A0dd if=3D$d of=3D/dev/null bs=3D1M count=3D100 > =A0done > > and report the times. tested it with 1gb instead of 100 mb sdg 1048576000 bytes (1.0 GB) copied, 9.89311 s, 106 MB/s sdj 1048576000 bytes (1.0 GB) copied, 10.094 s, 104 MB/s sdk 1048576000 bytes (1.0 GB) copied, 8.53513 s, 123 MB/s /dev/md6 1048576000 bytes (1.0 GB) copied, 11.4741 s, 91.4 MB/s /dev/mapper/data 1048576000 bytes (1.0 GB) copied, 34.4544 s, 30.4 MB/s bigfile 1048576000 bytes (1.0 GB) copied, 26.6532 s, 39.3 MB/s so the crypto indeed slows it down (and i'm surprised that it's that bad because i've read it's not a big hit on current CPUs and the X2 isn't new but not that old) but still read speed from md6 is worse than from one drive alone Johannes -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html