From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milan Broz Date: Thu, 09 Jul 2009 19:27:43 +0200 Subject: [PATCH] unknown segment types, part 1 In-Reply-To: <87ljmzcz28.fsf@twilight.int.mornfall.net.> References: <87ljmzcz28.fsf@twilight.int.mornfall.net.> Message-ID: <4A56288F.4080604@redhat.com> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Petr Rockai wrote: > the attached patch makes LVM handle unknown segment types by a simple > copy-through mechanism, i.e. whenever an unknown segment is encountered, it is > left intact (and preserved) by LVM. We may still want to limit changes to LVs > that contain unknown segments, and maybe even some heuristic to find LV > references in unknown segments (hard to tell). > > There's also one thread-unsafe bit in the patch, that's not so hard to fix, but > I'll do that when we know that this is the right direction we want to take. > > (The patch itself will probably need another iteration. Consider this to be a > draft.) After short testing (yes, there are nice bugs :-) I have several questions: - Why activate "unknown" segment by replacing it by error segment? I think that ignoring LV including unknown segment (with some error message) but not activate is better. Or use some configurable option? - Do we want code to preserve (read: kill unknown options) metadata when segment handler is not loaded? Isn't better just allow only read-only metadata operation (so "unknown" segment will appear only in-memory metadata, never on-disk). Possibly add some option to vgck to "fix" unknown segments. Milan