Re: pvmove thin volume doesn't move

[Zdenek Kabelac <zdenek.kabelac@gmail.com>]

Dne 19. 11. 25 v 18:22 matthew patton napsal(a):
> Right,  so LVMThin(1) conveniently omits "Oh BTW standard functionality like pvmove() is not implemented."
> 
> lvmthin is a sub-set or sub-class of LVM, therefore any reasonable person would assume all functionality cascades down. Because it pretty much does for everything else.
> 
>> lvm2 has 'no idea'  which disk space is in-use for any individual thin LV.
>> (there are tools like 'thin_ls/thin_rmap' for that)
> 
> And any reasonable person would assume lvmthin would have implemented the necessary hooks so that pvmove() would work by lvmthin handing lvm back a linked-list of all of the pieces in the correct order so they could be written to lvm(thick) or to another lvmthin pool. This is not that big of a cognitive leap.
> 
> That Linux LVM thin is missing "obvious" functionality is fine, it just needs to be stated very clearly.


Yep  thanks this is a  legit complain, we will improve our doc to be way more 
clear about this.

I've been also thinking - that adding support of 'dumb' mirroring of thinLV 
into pvmove - isn't a very difficult request - so we will see - although 
obviously copying  10TiB empty thin volume isn't going to be 'a fast 
operation' this way - but it's not any worse then a 'dd'.


Regards

Zdenek