From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Performance of a software raid 5 Date: Tue, 21 Apr 2009 15:46:09 +1000 Message-ID: <18925.23969.113047.133385@notabene.brown> 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: message from Johannes Segitz on Tuesday April 21 Sender: linux-raid-owner@vger.kernel.org To: Johannes Segitz Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tuesday April 21, johannes.segitz@gmail.com wrote: > On Tue, Apr 21, 2009 at 3:19 AM, NeilBrown wrote: > > Have you done any testing without the crypto layer to see what effe= ct > > 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. >=20 > tested it with 1gb instead of 100 mb >=20 > 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 >=20 > 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 I suspect you will see that improve when you add another drive that it isn't running degraded. NeilBrown -- 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