From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs Date: Wed, 4 Aug 2010 09:35:46 +0200 Message-ID: <20100804073546.GA7494@comet.dominikbrodowski.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org, xfs@oss.sgi.com, linux-kernel@vger.kernel.org List-Id: linux-raid.ids Hey, on a production system I run kernel 2.6.35 and XFS (rw,relatime,nobarrier) on a lvdevice of a vgroup consisting of five dm-crypt devices (cryptsetup -c aes-lrw-benbi -s 384 create) , each of which runs on a md-raid1 device (mdadm --create --level=raid1 --raid-devices=2) on two 750 GB ATA devices. The read performance is abysmal. The ata devices can be ruled out, as hdparm resulted in acceptable performance: > Timing cached reads: 9444 MB in 2.00 seconds = 4733.59 MB/sec > Timing buffered disk reads: 298 MB in 3.02 seconds = 98.73 MB/sec How can I best track down the cause of the performance problem, a) without rebooting too often, and b) without breaking up the setup specified above (production system)? Any ideas? perf(1)? iostat(1)? Thanks & best, Dominik