On Nov 03, 2006 15:30 +0100, Jan Kara wrote: > > - stripe unit and stripe width need to be exposed so defrag too > > can make correct placement decisions. > fs-specific thing... I think this is not just XFS-specific. It is very desirable to align large IO to the RAID stripe so that if you write stripe_width bytes you don't do 2 expensive read-modify-write steps, but rather a single write operation. Also RAID controllers have (large) internal cache "lines" and having aligned reads can help noticably, and also if array is doing RAID parity checking to avoid overhead of doing this for two stripes instead of one. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
