On Jun 15, 2010, at 8:13 PM, Edward Ned Harvey wrote: >> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- >> boun...@opensolaris.org] On Behalf Of Bob Friesenhahn >> >> It is good to keep in mind that only small writes go to the dedicated >> slog. Large writes to to main store. A succession of that many small >> writes (to fill RAM/2) is highly unlikely. Also, that the zil is not >> read back unless the system is improperly shut down. > > Can anyone verify this? I thought the decision for small vs large sync > writes to go to log vs main store was determined by zfs_immediate_write_sz > and logbias. > > logbias was introduced in snv_122, which is zpool 18 or 19. > zfs_immediate_write_sz seems to have been around forever (I see comments > about it as early as 2006). > > Then again, I can't seem to find my zfs_immediate_write_sz, via either zpool > or zfs. Can anybody say what version zpool introduced > zfs_immediate_write_sz, or perhaps I'm using the wrong commands to try and > see mine? zpool get all rpool | grep zfs_immediate_write_sz ; zfs get all > rpool | grep zfs_immediate_write_sz
It is an int, as in C, not a parameter tunable by zpool or zfs commands. For NFS service, it can be tuned by the client via wsize. > I thought, if you didn't explicitly tune these, all sync writes go to ZIL > before the main store. Can't seem to find any way to verify this. Cake. All sync writes go to the ZIL. The ZIL may be in the pool or in the separate log device :-) -- richard -- Richard Elling rich...@nexenta.com +1-760-896-4422 ZFS and NexentaStor training, Rotterdam, July 13-15, 2010 http://nexenta-rotterdam.eventbrite.com/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
