Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Neil Perrin
On 03/06/09 14:51, Miles Nordin wrote: "np" == Neil Perrin writes: np> Alternatively, a lockfs will flush just a file system to np> stable storage but in this case just the intent log is np> written. (Then later when the txg commits those intent log np> records are discarded)

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Miles Nordin
> "np" == Neil Perrin writes: np> Alternatively, a lockfs will flush just a file system to np> stable storage but in this case just the intent log is np> written. (Then later when the txg commits those intent log np> records are discarded). In your blog it sounded like there'

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Miles Nordin
> "jd" == Jim Dunham writes: jd> It is my understanding that the ZFS intent log (ZIL) satisfies jd> POSIX requirements for synchronous transactions, thus jd> filesystem consistency. maybe ``file consistency'' would be clearer. When you say filesystem consistency people imagine t

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Richard Elling
Jonathan Edwards wrote: On Mar 6, 2009, at 8:58 AM, Andrew Gabriel wrote: Jim Dunham wrote: ZFS the filesystem is always on disk consistent, and ZFS does maintain filesystem consistency through coordination between the ZPL (ZFS POSIX Layer) and the ZIL (ZFS Intent Log). Unfortunately for SN

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Neil Perrin
On 03/06/09 08:10, Jim Dunham wrote: Andrew, Jim Dunham wrote: ZFS the filesystem is always on disk consistent, and ZFS does maintain filesystem consistency through coordination between the ZPL (ZFS POSIX Layer) and the ZIL (ZFS Intent Log). Unfortunately for SNDR, ZFS caches a lot of an a

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Neil Perrin
I'd like to correct a few misconceptions about the ZIL here. On 03/06/09 06:01, Jim Dunham wrote: ZFS the filesystem is always on disk consistent, and ZFS does maintain filesystem consistency through coordination between the ZPL (ZFS POSIX Layer) and the ZIL (ZFS Intent Log). Pool and file sy

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Jim Dunham
Andrew, Jim Dunham wrote: ZFS the filesystem is always on disk consistent, and ZFS does maintain filesystem consistency through coordination between the ZPL (ZFS POSIX Layer) and the ZIL (ZFS Intent Log). Unfortunately for SNDR, ZFS caches a lot of an applications filesystem data in the

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Jonathan Edwards
On Mar 6, 2009, at 8:58 AM, Andrew Gabriel wrote: Jim Dunham wrote: ZFS the filesystem is always on disk consistent, and ZFS does maintain filesystem consistency through coordination between the ZPL (ZFS POSIX Layer) and the ZIL (ZFS Intent Log). Unfortunately for SNDR, ZFS caches a lot o

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Andrew Gabriel
Jim Dunham wrote: ZFS the filesystem is always on disk consistent, and ZFS does maintain filesystem consistency through coordination between the ZPL (ZFS POSIX Layer) and the ZIL (ZFS Intent Log). Unfortunately for SNDR, ZFS caches a lot of an applications filesystem data in the ZIL, therefore

Re: [zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Darren J Moffat
Jim Dunham wrote: Unlike UFS filesystems and lockfs -f, or lockfs -w, there is no 'supported' way to get ZFS to empty the ZIL to disk on demand. So even though one will get both ZFS and application filesystem consistency within the SNDR secondary volume, there can be many seconds worth of lost

[zfs-discuss] ZFS and SNDR..., now I'm confused.

2009-03-06 Thread Jim Dunham
A recent increase in email about ZFS and SNDR (the replication component of Availability Suite), has given me reasons to post one of my replies. Well, now I'm confused! A collegue just pointed me towards your blog entry about SNDR and ZFS which, until now, I thought was not a supported co