[lvm-devel] [BUG-REPORT] mirror legs in the same PV with --alloc anywhere

[Takahiro Yasui]

On 04/17/10 05:15, brem belguebli wrote:
> I think things are not clear about this one, and everyone is confused.

I believe that we agreed on what was our goal through this thread.

> Malahal (from IBM) and you have posted a few weeks ago design proposals
> and patches to add mirrored log capabilities and also the fact that it
> could be located on the mirror legs (pv in our cases) by using
> alloc_anywhere.
> 
> alloc_anywhere, as described in the man page is to let LVM put the data
> logical extents where ever it wants (not strict allocation policy) which
> is, in case a mirror is expected completely a nonsense.

Yes, you are right. We can't expect where logical extents are
allocated for '--alloc anywhere'

> You may, (this is a suggestion), when lvcreating a mirror with
> mirrored-log
> - force strict allocation for the LE's (otherwise it' nonsense)
> - put the mirrored log leg on each PV
> - And may be disable alloc anywhare when creating mirrors ?

I think that 'mirrored log' capability is very useful and enhancing
availability is our next step. It is helpful if users can directly
build a mirror volume, which has a mirrored log and is built on two
physical devices and also each physical device contains a mirror
leg and a mirror log, by a simple command line.

I hope this explanation would be helpful.

Thanks,
Taka