[dm-devel] [BUG] multipath-tools: uuid has become meaningless

[Hannes Reinecke]

Malahal Naineni wrote:
> Hannes Reinecke [hare at suse.de] wrote:
>> Malahal Naineni wrote:
>>> This is where I was heading. I did some investigation and found that we
>>> really need to rename to wwid based names before we finally rename to
>>> the intended name. So we may actually have two passes just to rename
>>> (first to wwid based names and then to actual names).  Also the current
>>> code doesn't do rename followed by reload even if it is needed. Someone
>>> sets friendly name and some other defaults that need reload like path
>>> grouping policy etc, we just rename! Probably a bug in itself.
> 
>> You sure? I would rather rely on device-mapper uuids here.
> 
> Hannes, I am not sure what you are referring to when you say, "You
> sure?" Are you saying if I am sure about this bug? If so, you can see
> yourself by swapping couple entries in the bindings file. As I said,
> you will notice this bug only when you enable 'user_friendly_names' in
> initrd in real life!
> 
Well, I wanted to inquire about the double renaming thing.
But

>> So we can use the known naming scheme for the uuid to regenerate the
>> wwid; with this we can identify/access the device and we should be able to
>> make do with just one pass.
> 
> Say, you have "mpath0[uuid0]" and "mpath1[uuid1]" loaded currently.  How
> can we rename mpath0 to mpath1 and vice-versa? It does require an
> intermediate step of renaming to something else, right? 
>  
is a valid point. So yes, we have to put in a renaming mechanism.
So falling back to wwid should work here.

Sorry for the noise, you are correct here.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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