Re: clustered MD

[David Teigland <teigland@redhat.com>]

On Tue, Jun 09, 2015 at 02:26:25PM -0500, Goldwyn Rodrigues wrote:
> On 06/09/2015 01:22 PM, David Teigland wrote:
> >I've just noticed the existence of clustered MD for the first time.
> >It is a major new user of the dlm, and I have some doubts about it.
> >When did this appear on the mailing list for review?
> 
> It first appeared in December, 2014 on the RAID mailing list.
> http://marc.info/?l=linux-raid&m=141891941330336&w=2

I don't read that mailing list.  Searching my archives of linux-kernel, it
has never been mentioned.  I can't even find an email for the md pull
request that included it.

The merge commit states:

- "experimental" code for managing md/raid1 across a cluster using
     DLM.  Code is not ready for general use and triggers a WARNING if
     used.  However it is looking good and mostly done and having in
     mainline will help co-ordinate development.

That falls far short of the bar for adding it to the kernel.  It not only
needs to work, it needs to be reviewed and justified, usually by showing
some real world utility to warrant the potential maintenance effort.