Tao Chen writes: > Hello Robert, > > On 6/1/06, Robert Milkowski <[EMAIL PROTECTED]> wrote: > > Hello Anton, > > > > Thursday, June 1, 2006, 5:27:24 PM, you 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. >
One potential optimization in this space could cover the situation of small writes that updates file in sequential order. As it stands, on the first such write to a block we have to Input the block from disk. I imagine that we could delay the input phase as long as we are write-streaming to the block (SMOP). If the load is such that the whole block gets dirty before the transaction group closes, we could save the Input operation. -r _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
