On Mon, Dec 20, 2004 at 05:25:03PM +0100, Christian Mayrhuber wrote: > Disk barriers are only in since 2.6.9, so maybe these get turned on per > default after some more testing. That did happen to the data=ordered journal > mode.
I was under the impression that they were on by default. I wish this was documented somewhere; it's very important and i bet a LOT of sysadmins don't even consider the problems of having write-back caching enabled. At least most scsi drives come with it disabled by default. There's only wb support for ata and sata, fwih, too. A quick grep didn't help me find if there's any other barrier mode other than flush. It looked like reiserfs had support specifically for flush mode. I would have thought it'd be done just as a call to something like blkwb(). What about software raid? Are the barriers pushed through the raid layer? There's been some interesting discussion about this subject on the netbsd tech-kern list, btw. -- Tom Vier <[EMAIL PROTECTED]> DSA Key ID 0x15741ECE
