From mboxrd@z Thu Jan 1 00:00:00 1970 From: "NeilBrown" Subject: Re: Write intent bitmaps. Date: Tue, 25 Aug 2009 06:25:14 +1000 (EST) Message-ID: <09198ab3b722ad5aa40d32f78626953e.squirrel@neil.brown.name> References: <5c45fce80908230116o2f129ab4y8d255cbe83bfac5b@mail.gmail.com> <87ws4t4bjz.fsf@frosties.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Simon Jackson Cc: "linux-raid@vger.kernel.org" List-Id: linux-raid.ids On Tue, August 25, 2009 12:39 am, Simon Jackson wrote: > > > I am trying to use write intent bitmaps on some RAID 1 volumes to reduce > the rebuild times in the event of hard resets that cause the md driver to > kick members out of my arrays. > > I used the mdadm --grow /dev/md0 --bitmap=internal and this appeared to > succeed, but when I tried to examine the bitmap I get an error. > > > :~$ sudo mdadm --grow /dev/md0 --bitmap=internal > :~$ sudo mdadm -X /dev/md0 > Filename : /dev/md0 > Magic : 00000000 > mdadm: invalid bitmap magic 0x0, the bitmap file appears to be corrupted > Version : 0 > mdadm: unknown bitmap version 0, either the bitmap file is corrupted or > you need to upgrade your tools Quoting from the man page: -X, --examine-bitmap Report information about a bitmap file. The argument is either an external bitmap file or an array component in case of an internal bitmap. Note that running this on an array device (e.g. /dev/md0) does not report the bitmap for that array. Particularly read the last sentence. Then try mdadm -X /dev/sda5 NeilBrown > > cat /proc/mdstat > Personalities : [raid1] > > md0 : active raid1 sda5[0] sdb5[1] > 7823552 blocks [2/2] [UU] > bitmap: 29/239 pages [116KB], 16KB chunk > > unused devices: > sjackson@mercuryst5:~$ sudo mdadm -X /dev/md0 > Filename : /dev/md0 > Magic : 00000000 > mdadm: invalid bitmap magic 0x0, the bitmap file appears to be corrupted > Version : 0 > mdadm: unknown bitmap version 0, either the bitmap file is corrupted or > you need to upgrade your tools > > Do I really have a usable bitmap on the device in this case? > > Thanks for any input. > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >