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Protection Overhead for multiple Node Pools OneFS 8.x
How do I evaluate the protection overhead in a SmartPool with two different node pools.
I have a 19 node cluster that is made up of two different node pools. One with 8 nodes and the other with 11 and the protection level is set to +2d:1n for both pools. I'm looking at the WebGUI and under the Storage Pool Summary for SmartPools, there is a recommendation to increase the protection level of one of my Node Pools from +2d:1n to +3d:1n1.
I'm skeptical of evaluating the cluster overhead by total number of nodes because a file and it's parity bit or bits must be written and exist in the same Node Pool. - please correct me if this is not accurate.
Node Pool 1
8 Nodes +2d:1n 12.5% overhead - per chart below
Node Pool 2
11 Nodes +3d:1n1d 17% overhead - per chart below
AdamFox
254 Posts
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March 29th, 2017 12:00
Not sure what you're asking but you pretty much understand how it works. The files in the node pool one will have about 12.5% overhead and the files in node pool 2 will have about 17% overhead. I say 'about' because the real numbers are dependent on other things like file size. Overhead is actually determined on the fly as the file is created and updated so all calculations involving the future are estimates.