On Thu, Jun 01, 2006 at 06:40:15PM -0500, Tao Chen wrote: > >ABR> What about small random writes? Won't those also require reading > >ABR> from all disks in RAID-Z to read the blocks for update, where in > >ABR> mirroring only one disk need be accessed? Or am I missing something? > > > >If I understand it correctly ZFS always writes new block - no updates. > >It also means it should be able to write sequentially most of the time > >even if application is issuing random writes/updates. > > When the "update write" is smaller than the orignal block, you have to > read the rest of the original block in order to write a new block. I > think that's what Anton was refering.
indeed - I don't think this should be a problem for the Maildir workload, as files are never modified after they are written (only renamed, read and unlinked). this behaviour means that the writes should always be efficient, but the reads are something that I will need to benchmark. which reminds me, I need to write up a filebench profile for typical Maildir delivery and POP3 access. grant. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
