Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992660AbWJTQlm (ORCPT ); Fri, 20 Oct 2006 12:41:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992668AbWJTQlm (ORCPT ); Fri, 20 Oct 2006 12:41:42 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:33482 "EHLO moutng.kundenserver.de") by vger.kernel.org with ESMTP id S2992660AbWJTQll (ORCPT ); Fri, 20 Oct 2006 12:41:41 -0400 From: Christian To: linux-kernel@vger.kernel.org Subject: Device mapper/LVM throughput problem Date: Fri, 20 Oct 2006 18:41:31 +0200 User-Agent: KMail/1.9.5 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200610201841.31435.christiand59@web.de> X-Provags-ID: kundenserver.de abuse@kundenserver.de login:176b6e6b41629db5898eee8167b5e3a0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2614 Lines: 77 Hello lkml! I've just tested the disk throughput on my machine using hdparm and found some puzzling results. I have a two disk nvidia fakeraid 0 configuration using dmraid and lvm. When testing the single disks, I get good results just like when testing the dmraid mapping. When I test the throughput on a raid partition or the LVM Volumes I get very bad performance. Has anybody seen something like this before? single disks: (good results) user@ubuntu:~$ sudo hdparm -Tt /dev/sd[ab] /dev/sda: Timing cached reads: 3384 MB in 2.00 seconds = 1693.17 MB/sec Timing buffered disk reads: 210 MB in 3.02 seconds = 69.56 MB/sec /dev/sdb: Timing cached reads: 4096 MB in 2.00 seconds = 2049.10 MB/sec Timing buffered disk reads: 208 MB in 3.01 seconds = 69.01 MB/sec dmraid mapping: (good results) user@ubuntu:~$ sudo hdparm -Tt /dev/mapper/nvidia_cbcaiacc /dev/mapper/nvidia_cbcaiacc: Timing cached reads: 3380 MB in 2.00 seconds = 1690.50 MB/sec HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device Timing buffered disk reads: 392 MB in 3.01 seconds = 130.05 MB/sec HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device third (or any other) partition on raid (bad throughput): user@ubuntu:~$ sudo hdparm -Tt /dev/mapper/nvidia_cbcaiacc3 /dev/mapper/nvidia_cbcaiacc3: Timing cached reads: 3272 MB in 2.00 seconds = 1636.72 MB/sec HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device Timing buffered disk reads: 158 MB in 3.00 seconds = 52.63 MB/sec HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device LVM Volume (even worse) user@ubuntu:~$ sudo hdparm -Tt /dev/VolGroup00/LogVol00 /dev/VolGroup00/LogVol00: Timing cached reads: 3636 MB in 2.00 seconds = 1818.96 MB/sec HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device Timing buffered disk reads: 114 MB in 3.01 seconds = 37.82 MB/sec HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device So on LogVol00 residing on a two disk striped set I get only 38MB/s throughput! I would anticipate something in the range of 130-140 MB/s user@ubuntu:~$ uname -a Linux ubuntu.localnet 2.6.18-rc7 #2 SMP Wed Sep 13 11:28:41 CEST 2006 x86_64 GNU/Linux -Christian - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/