[DRBD-user] thin volume looses sparse during replication

[Pierre-Philipp Braun]

Hello

when performing the initial synchronization of an thin-provisioned LVM2 
volume from primary to secondary, I can see data gets written on 
secondary and the resulting LVM2 volume, although supposedly "thin", 
ends up with 100% used data.

To fix that, I need to `blkdiscard` it (even from the primary, that 
works too) after synchronization.  And this is an extraordinary painful 
step to go through.  Because of that limitation, I cannot create many 
drbd resources that would over-commit physically available space at 
once: I need to sync/discard the resources step by step...

Is there a way to make the initial replication keep being thin (or 
sparse, as in file-system terminology, when dealing with zeroes)?

Thank you!

Best regards,
-- 
Pierre-Philipp Braun
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