From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:37225 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754581AbbKMKTi (ORCPT ); Fri, 13 Nov 2015 05:19:38 -0500 Message-ID: <5645B906.8030402@oracle.com> Date: Fri, 13 Nov 2015 18:18:46 +0800 From: Anand Jain MIME-Version: 1.0 To: Qu Wenruo CC: linux-btrfs@vger.kernel.org Subject: Re: [PATCH 00/15] btrfs: Hot spare and Auto replace References: <1447066589-3835-1-git-send-email-anand.jain@oracle.com> <5643F62D.6050703@cn.fujitsu.com> In-Reply-To: <5643F62D.6050703@cn.fujitsu.com> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Thanks for the comments. > Let's take the following example: > > 1) 2 RAID1 + 1 spare > (A + B) + C > > 2) 3 RAID1 > (A + B + C) > At least in normal operation case, case 1) makes device C useless, and Yes. > For case 2), we can just relocate and recover the bad chunks in B. > It it should only need to copy 6G data. Case 2 is Wrong in the context of spare. Unless space usage is limited to 1/3 of total space. But when you do that, case 1 drawback will equally apply to case 2 as well. > It it should only need to copy 6G data. Its true as long as you don't replace the failed B and bring the configuration to its original. However when you do that, Data moved will be more than case 1. So this is not fully correct. Thanks, Anand