Objective 1.2 – Install and Configure VMware ESXi

Enable/Size/Disable memory compression cache

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Enable/Size/Disable memory compression cache
ESXi provides a memory compression cache to improve virtual machine performance when you use memory over-commitment. When a host's memory becomes overcommitted, ESXi compresses virtual pages and stores them in memory.

Accessing compressed memory is faster than accessing memory that is swapped to disk so memory compression allows you to over-commit memory with minimum performance penalty. When a virtual page needs to be swapped, ESXi first attempts to compress the page. Pages that can be compressed to 2 KB or smaller are stored in the virtual machine's compression cache, increasing the capacity of the host.Memory compression is enabled by default.

Enabling/Disabling Memory Compression

Open vCenter server and select Hosts and Clusters
Select a host and click the Configuration tab
From the Software tab click Advanced Settings
Set Mem.MemZipEnable
Enter 1 to enable or enter 0 to disable the memory compression cache.

Configuring Memory Compression

Open vCenter server and select Hosts and Clusters
Select host and click the Configuration tab
From the Software tab click Advanced Settings
Set Mem.MemZipMaxPct
This value must be between 5 and 100 percent.

References:

http://pubs.vmware.com/vsphere-50/index.jsp?topic=/com.vmware.vsphere.resmgmt.doc_50/GUID-FD71CBCA-E97C-4EFA-8A1B-32C09D5DF2A1.html
http://blog.edgoad.com/2011/11/vcp5-enablesizedisable-memory.html

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