That's true, but if you look at slides 24 & 25 of http://www.ddrdrive.com/zil_accelerator.pdf you'll see seek distributions for a SLOG device with the ZILs for five filesystems - although each ZIL is broadly append only (slides 21 and 22), there is still a lot of seeking going on. Of course if you only had one active FS on a pool, the activity would be almost pure append, so sequential write performance would be the most important factor.
On 7 Jun 2012, at 00:10, Bob Friesenhahn wrote: > On Wed, 6 Jun 2012, Matt Clark wrote: > >> Yes, it's interesting to consider the possible real world performance. ZIL >> writes, even by DDRDrive's stats, are very closely clustered around the tail >> of the ZIL, with most seeks being to near locations - it's certainly not >> going to seek more than 8 gig away. So probably just leaving it at one big >> partition would be fine too. > > The ZIL is not used for anything but to replay pending synchronous writes if > the system unexpectedly reboots. It is not used as a source of data while > the system is running. It is normally a write-only device. > _______________________________________________ OpenIndiana-discuss mailing list OpenIndiana-discuss@openindiana.org http://openindiana.org/mailman/listinfo/openindiana-discuss
