I know by default TPS is disabled for inter-vm sharing for security reasons. Our DMZ servers resides in a separate VM cluster from our production VM. My question is has anyone enabled this for inter-vm sharing and if so how much memory saving did it by you?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
ah, Transparent Page Sharing....I'm surprised this has not reared it's ugly head before on Experts Exchange, how VMware decided to disable this function by default with the release of ESXi 5.5 Update 2d,and not really tell many of us!

and this was due to a very low risk security concern, that VMware decided to turn if OFF  by default.

Many of our Clients have re-enabled this now, because it does help, especially with oversubscription e.g. it does save memory.

After the patch we have seen 200GB in shared pages, which have resulted in memory contention issues. (on some workloads, so the savings are different per host, cluster and environment)

It is believed to be low risk see here

Here is a tool you can use, to check if you still have enough memory, if it's disabled versus enabled!

So in response to your question.

1. Yes we have enabled it. (The business considers it low risk versus memory saved!)

2. It saved 200GB. (memory saved on this workload).

Otherwise you've just got to increase your budget and put more memory in hosts!
compdigit44Author Commented:
Does the changes require a reboot?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
It does not require a reboot,  but lots of options here to confuse you... because since it was disabled, they are no various different options based on Host version, and salting!

see here
compdigit44Author Commented:
IN the following article what does the term memory sharing between VMs with the same salt mean?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
identical values, which allows different virtual machines to share the memory!

e.g. 0, 1 or 2.... etc

different values, do different things. as per

The idea being you give the VMs which want to share, the same number, e.g. both 1 , 2 etc

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