From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco Subject: raid1 performance Date: Sun, 25 Jul 2010 14:58:37 +0000 (GMT) Message-ID: <443220.14357.qm@web28508.mail.ukl.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi all, I'm posting again the same message because I have had some problem subscribing the list so i'm not sure it has been received: 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 test 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 ? I'm running the test on a Centos 5.4, /dev/md2 is a mounted and used block device (lvm on top of md2 and the root partion on the lvm volume group), but the machine was quite idle during the tests. The controller is an Intel ICH9 with AHCI enabled. thank you in advance! Marco