Re: thin pool powerfail tests and data loss

Dne 08. 09. 24 v 3:37 Lakshmi Narasimhan Sundararajan napsal(a):
> Hi Team,
> Greetings!
> 
> In my experiments with thin pool and power cycle tests, I find that
> the inflight data has not been persisted, even if there is a sync
> following write that got completed.
> 
> suppose we have the following bdev stackup:
> bdevs(multi) -> mpath -> lvm pv -> lvm vg -> lvm thin pool -> multiple
> thin vols.
> 
> Each of the thin vols that has inflight data, has a corresponding sync
> checkpoint periodically. The expectation is all writes before the sync
> are persisted to disk and can survive power reset tests.
> 
> Like below seq on many thin vols on the thin pool.
> write -> write -> write -> fsync(fd) -> write -> write -> fsync(fd) -> ..etc
> 
> Now my code only does a fsync(fd) on the thin volume (block device directly).
> There are no fs mounts on the volume.
> Is this sufficient or should the thin pool (/dev/mapper/pool) also be
> synced along?
> What would be the proper sequence of sync actions to survive a power reset?
> 
> I am also trying to validate if this is an issue because mpath is
> involved in any way(another dm layer in between), but would appreciate
> some guidance in this
> regard.

Hi

Could you please retest your issue with  recent lvm2  (>= 2.03.24) and recent 
linux kernel   >= 6.9

Regards

Zdenek