ElevenB2003
Enthusiast
Enthusiast

Floating Pool - Re-balance between 2 LUNs.

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I have a floating pool of 32 linked clones setup and running. This pool has 2 shared data stores assigned to it and I'm NOT specifying it to use 1 for replicas and the other for linked clones. My understanding is that it should evenly split the clones and replicas between these 2 LUNs when I perform a rebalance. However, this is not the case - after the rebalance, all 32 of the clones are sitting on a single LUN and the additional LUN sits unused.  Any help would be appreciated!

Thanks!

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mittim12
Immortal
Immortal

Ok, found the older post where a VMware employee described how the re balance works.   For some reason I have the hardest time trying to remember this and I always want to say if it's on free space.    Anyways here it is.  .

If you choose multiple datastores for linked clone pool creation, View selects a datastore based on  "Lowest Population Density" (and not based on largest available space) For example. If you have a 100 GB datastore with no VM inside, and 200GB datasore with 80 GB used space, though the 2nd datastore has 120 B free, View selects the first datastore, as it has lowest population density.

By doing this it ensures that a datastore which has less population is always selected and thus by balancing the storage usage.

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mittim12
Immortal
Immortal

The rebalance  should go by VM density and maybe free space.

ElevenB2003
Enthusiast
Enthusiast

Thanks for the response - Ideally what I'm looking for is to have a replica on each data store and evenly split the clones between them so half of the clones and a replica are on 1 and the other half and another replica reside on the other.  Granted, right now there are only 32 clones in the pool and performance is not really an issue, but as we scale up to bigger pools I know that you really don't want more than about 64 clones on a single LUN. 

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mittim12
Immortal
Immortal

Ok, found the older post where a VMware employee described how the re balance works.   For some reason I have the hardest time trying to remember this and I always want to say if it's on free space.    Anyways here it is.  .

If you choose multiple datastores for linked clone pool creation, View selects a datastore based on  "Lowest Population Density" (and not based on largest available space) For example. If you have a 100 GB datastore with no VM inside, and 200GB datasore with 80 GB used space, though the 2nd datastore has 120 B free, View selects the first datastore, as it has lowest population density.

By doing this it ensures that a datastore which has less population is always selected and thus by balancing the storage usage.

View solution in original post

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ElevenB2003
Enthusiast
Enthusiast

This is exactly the explanation I was looking for. I wasn't able to really find anything about rebalance in documentation or online.  Thanks!

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