From mboxrd@z Thu Jan 1 00:00:00 1970 From: Justin Piszcz Subject: Linux Software RAID Bitmap Question Date: Sun, 25 Feb 2007 09:05:14 -0500 (EST) Message-ID: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Anyone have a good explanation for the use of bitmaps? Anyone on the list use them? http://gentoo-wiki.com/HOWTO_Gentoo_Install_on_Software_RAID#Data_Scrubbing Provides an explanation on that page. I believe Neil stated that using bitmaps does incur a 10% performance penalty. If one's box never (or rarely) crashes, is a bitmap needed? The one question I had regarding a bitmap is as follows: The mismatch_cnt file. If I have bitmaps turned on for my RAID DEVICES, is it possible that the 'mismatch_cnt' will be updated when it finds a bad block? That would be VERY nice instead of running a check all the time. Justin.