[linux-lvm] Testing the new LVM cache feature

[Alasdair G Kergon]

On Thu, May 29, 2014 at 09:47:20PM +0100, Richard W.M. Jones wrote:
> Is there a reason why fast and slow devices need to be in the same VG?
> I've talked to two other people who found this very confusing.  No one
> knew that you could manually place LVs into different PVs, and it's
> something of a pain to have to remember to place LVs every time you
> create or resize one.  It seems it would be a lot simpler if you could
> have the slow PVs in one VG and the fast PVs in another VG.
 
We recommend you use tags.  Much more flexible/dynamic solution than forcing
the use of separate VGs.

  pvchange --addtag ssd
  pvs -o+tags

  lvcreate ... $vg @ssd

to restrict the allocation the command performs to the PVs with the 'ssd' tag.

Alasdair