From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ron Edison Subject: writeback cache + h700 controller w/1gb nvcache, corruption on power loss Date: Sat, 14 Apr 2012 21:16:16 -0700 (PDT) Message-ID: <17899694.655.1334463376853.JavaMail.root@sys1.internetdefensetechnologies.com> References: <22130654.645.1334462335379.JavaMail.root@sys1.internetdefensetechnologies.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from sys1.internetdefensetechnologies.com ([66.212.19.80]:48093 "EHLO sys1.internetdefensetechnologies.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750732Ab2DOEQ3 (ORCPT ); Sun, 15 Apr 2012 00:16:29 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by sys1.internetdefensetechnologies.com (Postfix) with ESMTP id 68B1711FC440 for ; Sat, 14 Apr 2012 21:16:27 -0700 (PDT) Received: from sys1.internetdefensetechnologies.com ([127.0.0.1]) by localhost (sys1.internetdefensetechnologies.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1SdYPBTwTpAF for ; Sat, 14 Apr 2012 21:16:17 -0700 (PDT) Received: from sys1.internetdefensetechnologies.com (sys1.internetdefensetechnologies.com [66.212.19.80]) by sys1.internetdefensetechnologies.com (Postfix) with ESMTP id EAE2211FC43F for ; Sat, 14 Apr 2012 21:16:16 -0700 (PDT) In-Reply-To: <22130654.645.1334462335379.JavaMail.root@sys1.internetdefensetechnologies.com> Sender: kvm-owner@vger.kernel.org List-ID: dear list, I recently had a machine lose power that was unfortunately running between 15-20 kvm guests. The server is a Dell R710 with an H700 controller with 1gb of nvcache. Writeback cache is enabled on the controller. There is a mix of linux and windows guests, some with qcow2 format vdisks and others with raw format vdisks. Some of these guests have wb cache enabled on the vdisks and some do not. About a third of the guests experienced disk corruption after coming back up after the host lost power. Based on what I have read, this should not have happened using the above configuration. The operating system is Centos 6.2, this is all direct attached storage configured as raid 1 mirrors. I'm hoping someone has a comment or suggestion on this so that I can take action to prevent corruption in the future. The motivation to enable write caching is primarily performance. Thanks, Ron