On Fri, May 25, 2007 at 03:35:48AM +0200, Pallai Roland wrote: > On Fri, 2007-05-25 at 10:05 +1000, David Chinner wrote: > > > >It's a good question too, but I think the md layer could > > > >save dumb filesystems like XFS if denies writes after 2 disks are failed, > > > >and > > > >I cannot see a good reason why it's not behave this way. > > > > How is *any* filesystem supposed to know that the underlying block > > device has gone bad if it is not returning errors? > It is returning errors, I think so. If I try to write raid5 with 2 > failed disks with dd, I've got errors on the missing chunks. Oh, did you look at your logs and find that XFS had spammed them about writes that were failing? > The difference between ext3 and XFS is that ext3 will remount to > read-only on the first write error but the XFS won't, XFS only fails > only the current operation, IMHO. The method of ext3 isn't perfect, but > in practice, it's working well. XFS will shutdown the filesystem if metadata corruption will occur due to a failed write. We don't immediately fail the filesystem on data write errors because on large systems you can get *transient* I/O errors (e.g. FC path failover) and so retrying failed data writes is useful for preventing unnecessary shutdowns of the filesystem. Different design criteria, different solutions... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - 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
