From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Mamedov Subject: Re: raid1 performance Date: Sun, 25 Jul 2010 21:19:26 +0600 Message-ID: <20100725211926.7547c12e@natsu> References: <443220.14357.qm@web28508.mail.ukl.yahoo.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/hiwnSqvTzAbwR+zqwTNqD=l"; protocol="application/pgp-signature" Return-path: In-Reply-To: <443220.14357.qm@web28508.mail.ukl.yahoo.com> Sender: linux-raid-owner@vger.kernel.org To: Marco Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/hiwnSqvTzAbwR+zqwTNqD=l Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sun, 25 Jul 2010 14:58:37 +0000 (GMT) Marco wrote: > doing a simple performance tests i obtained some very unexpected results:= if > i issue hdparm -t /dev/md2 i obtain 61 - 65 MB/s while issuing the same t= est=20 > directly on the partitions which compose md2 (/dev/sda3 and /dev/sdb3) i > obtain 84 - 87 MB/s. I didn't expect a so big difference between md2 and = one > of its member. What can cause this difference ?=20 Maybe their read-ahead settings are different? Check out "blockdev --getra /dev/md2", and compare that with the same setting of the member disks. You can experiment with changing it by using "--setra" as well. --=20 With respect, Roman --Sig_/hiwnSqvTzAbwR+zqwTNqD=l Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEARECAAYFAkxMVf8ACgkQTLKSvz+PZwjEBgCfXOpL88YeOPcCjQL5dW2VzoxP UGQAn3Grq6KnsaqrK0EnZifYu6i9U0Py =/O2a -----END PGP SIGNATURE----- --Sig_/hiwnSqvTzAbwR+zqwTNqD=l--