Hi Matt,<div><br></div><div>Hope you will forgive a potentially silly question, but how do you perceive the relationship between HAMMER1 and HAMMER2 in the future? Will the second incarnation entirely supersede and replace the original?</div>
<div><br></div>At the point at which HAMMER2 is released, is it your intention that people automatically upgrade older HAMMER to it? The feature set is certainly compelling!<span></span><div><br></div><div>I ask because I saw a few messages per the past 6 months or so where people were talking about perhaps contributing fixes to the utilities e.g. the PFS softlink handling and I wondered what your feeling were about effort being spent in that direction.</div>
<div><br></div>Thanks, Alex J Burke.<br><div></div><div><br><div>On Friday, 3 May 2013, Matthew Dillon wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> HAMMER1 has a number of deficiencies in this area. It is possible<br>
to add additional block devices to a HAMMER1 filesystem but it's never<br>
been well tested and I don't recommend it.<br>
<br>
HAMMER1's best feature is mirror-copy and mirror-stream. There are<br>
deficiencies here as well, particularly the issue with the root<br>
filesystem not being a PFS. Mirroring slaves can be upgraded to masters<br>
but they cannot be downgraded again, so their best use is to track<br>
near real-time backups.<br>
<br>
Snapshots also work extremely well and the fine-grained history works<br>
quite well too.<br>
<br>
The multi-volume feature doesn't work as well as we would like, and<br>
HAMMER1 doesn't have any redundancy so if you lose a HD that filesystem<br>
is basically dead (would have to be rebuilt from one of the mirror<br>
slaves being used as a backup).<br>
<br>
HAMMER2 will solve a lot of these problems. HAMMER2 has a 'super-root'<br>
directory level above the root mount so mount points are basically just<br>
PFS's, including the root mount. Snapshots are writable, and there will<br>
be a copies mechanism that treats multiple volumes as separate logical<br>
filesystems (i.e. real redundancy), and will also be able to take on the<br>
duty of adding/removing storage from a live filesystem.<br>
<br>
HAMMER2 is not even remotely close to being production ready yet though.<br>
<br>
At this point in time I am only doing minor maintainance work on HAMMER1.<br>
All my efforts are going into HAMMER2.<br>
<br>
-Matt<br>
</blockquote></div></div>