Details
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Bug
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Resolution: Unresolved
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Major
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None
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None
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None
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3
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10148
Description
AFAICS, some lease code landed for HSM needs.
Unfortunately, leases have the same problems as SOM had in past, related to evictions.
On eviction, locks are cancelled on MDS and client. However, a new lease may conflict with open files, but after client eviction and later re-connect, client does not re-open files, while they are still opened on the client and it is able to proceed with its IO.
However, HSM has a layout lock as well, which is supposed to block such new IO.
do I understand correctly, that lease is always taken together with an exclusive layout lock? so that all the other clients, even if they were evicted in past, would be blocked on layout lock with their new IO ?
if not, lease lock gives no guarantee for recently evicted clients.
The 2nd problem is that the evicted state has a latency being propagated from MDS to client, when client does not know it has connection problems while it is already evicted - could be up to obd_timeout which could be also pretty long.
layout lock will not help here. The solution could be the same as with SOM - just deny all the HSM releases for X*obd_timeouts period after the last eviction, to be sure clients are aware about their evictions and have cancelled layout locks.
are these lease lock issues known and somehow resolved?