Guy wrote:
You were using skip/seek wrong.
typo - thanks.
This is just pseudo code? I use bash or ksh, you can't do "n=n+1".
You don't ever end, again pseudo code I assume.
Indeed - should have said - I wouldn't want anyone to cut'n'paste :) (and that typo shows why!)
I would only do this if the filesystem on md0 is not mounted.Yes - I thought it would be safe for / in single user and realised it wouldn't.
I was also thinking
n=0 while dd if=/dev/md0 of=/tmp/block count=x_for_efficiency skip=n dd of=/dev/md0 if=/dev/zero count=x_for_efficiency seek=n dd of=/dev/md0 if=/tmp/block count=x_for_efficiency seek=n n= n + 1 loop
in case something in a block/md layer was smart enough to see no changes and not write it for real - I really don't know but it's more paranoid.
Anyway - the question remains - would this be the right approach?
Hmm - I wonder what would be needed to make the resync code do this...
David
Guy
n=0 while dd if=/dev/md0 of=/tmp/block count=x_for_efficiency skip=n dd of=/dev/md0 if=/tmp/block count=x_for_efficiency seek=n n=n+1 loop
-----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of David Greaves Sent: Thursday, August 12, 2004 8:31 AM To: Guy Cc: 'Gordon Henderson'; 'Philip Molter'; linux-raid@xxxxxxxxxxxxxxx Subject: Re: Force parity resync on raid5?
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:
IOuch! 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
remember the system looks like it is re-building a failed disk, which isnot
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@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of Gordon Henderson Sent: Tuesday, August 10, 2004 5:04 AM To: Philip Molter Cc: linux-raid@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
