From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: Force parity resync on raid5? Date: Thu, 12 Aug 2004 13:31:12 +0100 Sender: linux-raid-owner@vger.kernel.org Message-ID: <411B6310.9000406@dgreaves.com> References: <200408120406.i7C46s309087@watkins-home.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200408120406.i7C46s309087@watkins-home.com> To: Guy Cc: 'Gordon Henderson' , 'Philip Molter' , linux-raid@vger.kernel.org List-Id: linux-raid.ids what about n=0 while dd if=/dev/md0 of=/tmp/block count=x_for_efficiency seek=n dd of=/dev/md0 if=/tmp/block count=x_for_efficiency seek=n n=n+1 loop ? This would read the good data and force a rewrite - would you need to stop any optimisers? David Guy wrote: >Ouch! No!! > >This would re-build data from parity!!! >He thinks his parity is bad. >He wants to re-build the parity from the data! >I don't know if this can even be done! >Recovering from a power failure does force a re-build (2.4), but from what I >remember the system looks like it is re-building a failed disk, which is not >what he wants to do. If the parity was good, re-building any 1 disk would >be fine. > >Guy > >-----Original Message----- >From: linux-raid-owner@vger.kernel.org >[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Gordon Henderson >Sent: Tuesday, August 10, 2004 5:04 AM >To: Philip Molter >Cc: linux-raid@vger.kernel.org >Subject: Re: Force parity resync on raid5? > >On Mon, 9 Aug 2004, Philip Molter wrote: > > > >>How do I force a parity resync on a raid5 array? Under 2.4, I would do >>this by hard cycling the box and when it came back up, it would >>automatically resync the array. Under 2.6, this appears to have gone >> >> >away. > >I don't know about 2.6, (still living with 2.4) but can't you simply do: > > raidhotremove /dev/mdX /dev/hdYZ > >followed by > > raidhotadd /dev/mdX /dev/hdYZ > >or /dev/sdYZ if SCSI disks... > >However, picking the right disk to remove might be tricky... And if you >were at all unsure about data on the disks, maybe rebooting and doing a >hard fsck of the partition(s) in maintenance mode might be a good thing >too... > >Good luck! >- >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 > >- >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 > > >