Re: ext3 journal on software raid (was Re: PROBLEM: Kernel 2.6.10 crashing repeatedly and hard)

Alvin Oga wrote:

hi ya brad

On Wed, 5 Jan 2005, Brad Campbell wrote:

quoted

Alvin Oga wrote:

quoted

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