[linux-lvm] Running thin_trim before activating a thin pool

[Zdenek Kabelac]

Dne 29. 01. 22 v 21:09 Demi Marie Obenour napsal(a):
> On Sat, Jan 29, 2022 at 08:42:21PM +0100, Zdenek Kabelac wrote:
>> Dne 29. 01. 22 v 19:52 Demi Marie Obenour napsal(a):
>>> Is it possible to configure LVM2 so that it runs thin_trim before it
>>> activates a thin pool?  Qubes OS currently runs blkdiscard on every thin
>>> volume before deleting it, which is slow and unreliable.  Would running
>>> thin_trim during system startup provide a better alternative?
>>
>> Hi
>>
>>
>> Nope there is currently no support from lvm2 side for this.
>> Feel free to open RFE.
> 
> Done: https://bugzilla.redhat.com/show_bug.cgi?id=2048160
> 
> 

Thanks

Although your use-case Thinpool on top of VDO is not really a good plan and 
there is a good reason behind why lvm2 does not support this device stack 
directly (aka thin-pool data LV as VDO LV).
I'd say you are stepping on very very thin ice...

Also I assume you have already checked performance of discard on VDO, but I 
would not want to run this operation frequently on any larger volume...

Regards

Zdenek