The automatic "preferred" node selection is indeed based on the number of vdisks, size is not taken into account because at creation time it is impossible to predict the IO rate on a particular vdisk.
In most cases, hosts see the paths to vdisks that go via preferred node as the "optimal" paths,
The paths via the other node of same IOgroup is considered as a "standby" path so not used for host traffic in normal operations.
But to be honest, I think it is OK that the IO's on an IOgroup are not equally distributed across both nodes of an IOgroup :
Each node of an IOgroup should be able to carry the load of all IO's :
Example is firmware upgrades where each node is not available for some time.
Also if you encounter a failure of 1 node, system should still perform as before - only redundancy should have been lost in this case
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Hans Populaire
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Original Message:
Sent: Sat July 16, 2022 04:24 PM
From: AnalogKid
Subject: Single IO Group - Preferred Node
When a volume is automatically assigned to a preferred node (say Node 1):
--Under normal operating conditions, does it always stay on Node 1
Automatic 'Node' assignment refers to which nodes have the least number of volumes.
(Consider a 2 node system)
But what happens if I create:
Volume1 - 8,000 GB
Volume2 - 1 GB
Volume3 - 10,000 GB
Volume4 - 2 GB
Does the system assign the 8TB and 10TB to Node 1 ?
and assign the 1GB and 2GB to Node 2 ?
If the System automatically assigns nodes, does it 'later on' automatically rebalance those nodes
i.e. Is there an automatic 'movedisk' command run? (I cant imagine this would be the case)
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AnalogKid
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