[zfs-code] Transaction consistency of ZFS

2009-12-06 Thread Anurag Agarwal
Hi, My reading of write code of ZFS (zfs_write in zfs_vnops.c), is that all the writes in zfs are logged in the ZIL. And if that indeed is the case, then yes, ZFS does guarantee the sequential consistency, even when there are power outage or server crash. You might loose some writes if ZIL has not

[zfs-code] Transaction consistency of ZFS

2009-12-06 Thread Andrey Kuzmin
On Sun, Dec 6, 2009 at 8:11 PM, Anurag Agarwal wrote: > Hi, > > My reading of write code of ZFS (zfs_write in zfs_vnops.c), is that all the > writes in zfs are logged in the ZIL. And if that indeed is the case, then IIRC, there is some upper limit (1MB?) on writes that go to ZIL, with larger ones

[zfs-code] Transaction consistency of ZFS

2009-12-06 Thread Neil Perrin
On 12/06/09 10:11, Anurag Agarwal wrote: > Hi, > > My reading of write code of ZFS (zfs_write in zfs_vnops.c), is that all > the writes in zfs are logged in the ZIL. Each write gets recorded in memory in case it needs to be forced out later (eg fsync()), but is not written to the on-disk log u

[zfs-code] Transaction consistency of ZFS

2009-12-05 Thread nxyyt
This question is forwarded from ZFS-discussion. Hope any developer can throw some light on it. I'm a newbie to ZFS. I have a special question against the COW transaction of ZFS. Does ZFS keeps the sequential consistency of the same file when it meets power outage or server crash? Assume foll