Comments on: Memory overcommitment, not for production servers.

By: petros

petros — Tue, 30 Aug 2011 14:09:14 +0000

While I agree with your post I must add that the overcommitment must be seen as a crucial advantage of VMWare’s ESX hypervisors over the competition – even in a production setting – since it improves flexibility by orders of magnitude.
Granted, one should not make a practice out of overcommiting memory resources, however, one will not have to reserve huge amounts of idle servers in one’s clusters to allow for high HA since… they don;t need to! One can keep a very small percentage of idle servers since even if a large proportion of the cluster’s resources fail, memory overcommit will kick in and easily save the day. The same cannot be said for the competition since with e.g. hyper-v or Xen, the degree of HA is decided by the number of reserved idle servers in clusters.

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Sun, 25 Jul 2010 01:21:09 +0000

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By: Kristen Drohan

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By: Broderick Kor

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By: admin

admin — Fri, 19 Mar 2010 14:10:39 +0000

You are right saying that memory overcommit is possible. However, my point here is that using overcommitment would reduce or cancel your ability to implement High Availability and Failover of production VM in the event a host as a hardware or other major failure and VM’s need to be transfered on other host of the cluster. Most article about overcommitment are considering only VDI or SMB. In the case of large enterprise, you have to keep in mind that HA and failover will be implemented and if you are overcommiting your memory, you will lose those abilities quite fast.

By: Kris

Kris — Fri, 19 Mar 2010 11:35:04 +0000

In the real world, mem overcommitment is actually used. How? Well, VMware recommends to do a max. overcommitment of 160-180 percent. So if your host has 24GB that gives about 38GB of memory to be commited. Most companies subtract 20 to 30 percent from this. Intel, for example, subtracts 20 percent giving about 30GB to be commited.

By: Conrad Veltri

Conrad Veltri — Thu, 18 Mar 2010 16:29:25 +0000

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