From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brad Campbell Subject: Re: ext3 journal on software raid (was Re: PROBLEM: Kernel 2.6.10 crashing repeatedly and hard) Date: Wed, 05 Jan 2005 16:02:09 +0400 Message-ID: <41DBD741.4070000@wasp.net.au> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Alvin Oga Cc: Andy Smith , linux-raid@vger.kernel.org List-Id: linux-raid.ids Alvin Oga wrote: > > hi ya brad > > On Wed, 5 Jan 2005, Brad Campbell wrote: > > >>Alvin Oga wrote: >> >>> for swap ... i personally don't see any reason to mirror >>> swap partitions ... >>> - once the system dies, ( power off ), all temp >>> data is useless unless one continues from a coredump >>> ( from the same state as when it went down initially ) >> >>I beg to differ on this one. Having spend several weeks tracking down random processes dying on a >>machine that turned out to be a bad sector in the swap partition, I have had great results by >>running swap on a RAID-1. If you develop a bad sector in a non-mirrored swap, bad things happen >>indeterminately and can be a royal PITA to chase down. It's just a little extra piece of mind. > > > okay .... if the parts of disks is bad that is used for swap, > mirroring might help ... > > but, i wonder, how/why the system used that portion of swap in the first > place > - even for raid, if sector-10 in swap is bad, why would raid keep > trying to write there instead of to sector-1000 Picture lpd gets swapped out on a friday night. Over the weekend it is not used and the drive develops a bad sector in the middle of the file. Monday morning I want to print and the system tries to page lpd back in again. *boom*. I have not looked at the system swap algorithms, but I doubt they include automatic bad block management and read after write verification. I'm making big assumptions here, but I'm assuming they rely on a bad block table created by mkswap and an otherwise clean, functioning swap area. Regards, Brad