On Saturday February 23, asmith@umdgrb.umd.edu wrote: > > > > > > Not very.... but what filesystem are you usinf over your RAID5 array? > > XFS? > > > > I use ext3. Do you know what causes these errors? Yes. The message (it isn't really an error) indicated that the raid5 layer got a request for a sector when it already had a pending request for that sector. This tends to suggest that something odd is going on with caching somewhere higher up. Normally if a particular block on disc had been requested and it was wanted again, the fact that a request was already pending would be noticed and it would not be repeated. If it had been a write request (e.g. multiple 1 requests for ...) then it could be a cause for concern as it means that someone had requested two, presumably different, blocks of data to be written to the same location on disc. There is no guarantee which order they would get written in, so this is a problem waiting to happen. XFS used to do this occasionally (which is why I asked about XFS) but that has probably been fixes. In your case it was "multiple 0 requests" meaning read requests which is less likely to cause data corruption, but is still odd. The filesystem is unlikely to ask for the same block twice without first waiting for the first request to succeed. If it is, the filesystem developers should be told. Another possibility is that you are accessing the device (/dev/md0 or whatever) directly at the same time that the filesystem is accessing it. e.g. you might be running dumpfs or fsck (or just dd) on a filesystem that is mounted. This might be OK is some circumstances, but you should realise that there is no cache coherancy between the two access paths so you might not be getting what you expect. Is this possibly what is happening? NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
