Hi, all

Why does VDSM choose the centric-control instead of distribute-control in the 
management of LVM metadata?

Is that any historical reason for this?


From: vdsm-devel-boun...@lists.fedorahosted.org 
[mailto:vdsm-devel-boun...@lists.fedorahosted.org] On Behalf Of tsiren tsi
Sent: Thursday, June 20, 2013 11:00 PM
To: vdsm-devel@lists.fedorahosted.org
Subject: [vdsm] why does VDSM use the SPM to manage and protect the LVM 
meta-data ?


As is known to all, sanlock can manage and protect the meta-data which would be 
modified one by one.
Sanlock can be used as the cluster lock with the ids file and lease file. Paxos 
lease ensures the consistence between all the nodes.
In the condition of modifying LVM meta-data(create, delete, extend, and etc) , 
the sanlock acquire function would be called to lock the block(LUN). Once the 
operation finished, we could call the sanlock release function to unlock the 
block.In this case, we could no longer maintain the two modules(mailbox and 

I think that it would be simplify the realization of VDSM. Does anyone consider 
this question?
If we just used the sanlock as the cluster lock, could be the frequent usage of 
lock(or aquire) and unlock(or release) a performance bottleneck of sytem?

Appreciate for your repy, thank you
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