Hi,
Obviously, moving (''renaming'') files between ZFSs on the same
zpools is just like a move between any other two filesystems, requiring full
copy of the data and deletion of the old file.
I was wondering if there is (and why there isn''t) an optimization
inside ZFS, thus that copy between ZFSs on the same zpool would be instantaneous
or near-so. After all, no blocks /really/ need to be copied, it''s more
about ZFS finding out that it''s a move within the same zpool and inode
modifications at the source / target.
Thoughts?
- Yaniv
This message posted from opensolaris.org
Yaniv Aknin wrote:> Hi, > > Obviously, moving (''renaming'') files between ZFSs on the same zpools is just like a move between any other two filesystems, requiring full copy of the data and deletion of the old file. > > I was wondering if there is (and why there isn''t) an optimization inside ZFS, thus that copy between ZFSs on the same zpool would be instantaneous or near-so. After all, no blocks /really/ need to be copied, it''s more about ZFS finding out that it''s a move within the same zpool and inode modifications at the source / target. > > Thoughts? > >We beat this one into the dust last December. See thread: http://mail.opensolaris.org/pipermail/zfs-discuss/2007-December/044975.html -- richard
Thanks for the reference. I read that thread to the end, and saw there are some complex considerations regarding changing st_dev on an open file, but no decision. Despite this complexity, I think the situation is quite brain damanged - I''m moving large files between ZFSs all the time, otherwise I can''t separate the tree as I''d like to, and it''s fairly annoying to think these blocks are basically not doing anything at 50mb/s. I think even a hack will do for a start (do I hear ''zmv''). Thoughts? Objections? This message posted from opensolaris.org
Yaniv Aknin wrote:> Thanks for the reference. > > I read that thread to the end, and saw there are some complex considerations regarding changing st_dev on an open file, but no decision. Despite this complexity, I think the situation is quite brain damanged - I''m moving large files between ZFSs all the time, otherwise I can''t separate the tree as I''d like to, and it''s fairly annoying to think these blocks are basically not doing anything at 50mb/s. > > I think even a hack will do for a start (do I hear ''zmv''). > > Thoughts? Objections? >It is filed as an RFE - 6650426 and 6483179 are related. Darren