[linux-lvm] Howto change cachepolicy on cached thinpool devices?

[Zdenek Kabelac]

Dne 15.5.2017 v 15:25 Oliver Rath napsal(a):
> Hi list,
> 
> caching the _tdata part of a thinpool works fine now. Unfortunatly with
> lvchange it is not possible to change the policy (vg:dmivg,
> cachepool:dmipool,thinpool:winthinpool):
> 
> # lvchange --cachepolicy cleaner dmivg/dmicache
>    Operation not permitted on hidden LV dmivg/dmicache.
> 
> # lvchange --cachepolicy cleaner /dev/mapper/dmivg-winthinpool_tdata
>    Operation not permitted on hidden LV dmivg/winthinpool_tdata.
> 
> # lvchange --cachepolicy cleaner dmivg/winthinpool
>    Command on LV dmivg/winthinpool does not accept LV type thinpool.
> Required LV types are cache cachepool .
>    Command not permitted on LV dmivg/winthinpool.
> 
> The only possibility at the moment seems to change it via lowlewel
> dmsetup command.
> 
> # dmsetup status dmivg-winthinpool_tdata
> 0 7730954240 cache 8 1458/9216 128 720896/720896 4608761 7143953 1177059
> 5866353 40700 761596 2993 2 metadata2 writeback 2 migration_threshold
> 2048 smq 0 rw -
> 
> ...
> 
> How can this be done with lv*?

Hi

By opening BZ  at http://bugzilla.redhat.com/  for lvm2 ;)
Seem this has got lost in various code changes.

Should be easy to add this to supported variant.

Regards

Zdenek