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Versions are critical - we need them for multiple things, let's make
sure we get exactly the right thing in ZFS also.<br>
<br>
- Peter -<br>
<br>
Andreas Dilger wrote:
<blockquote cite="mid:20080211181850.GA6552@webber.adilger.int"
type="cite">
<pre wrap="">On Feb 08, 2008 16:55 +0100, Aurelien Degremont wrote:
</pre>
<blockquote type="cite">
<pre wrap="">But the touch could be problematic. Lustre gurus, is there another time
field we could use instead ? Should we add a
"last-modification-field-which-ignore-touch" ? Is this really a problem
is we use display a "touched" time ? In this case, we display what the
user set on the file, we suppose he did it in purpose.
</pre>
</blockquote>
<pre wrap=""><!---->
There was work done in ext4/ldiskfs to add a 64-bit "version" field to
the on-disk inode, for use by lustre and NFSv4. In the ldiskfs case
Lustre was free to store any information in this field it wanted. The
planned use for this field is for "version based recovery" and it has
the semantic that it is an increasing (though not necessarily sequential)
version number that tracks any change to the file. This is stored in
each inode on the MDT and each object on the OSTs.
In ZFS I believe there is also a "last modified transaction group" (txg)
number stored with each dnode that could be used in a similar manner.
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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