VMWare & Xen: mysql memory usage differs greatly
Posted by: Clayton Bell
Date: November 08, 2009 05:01PM

Hello forum

I have two identical Red Hat EL 5.2 virtual machines - one running under Xen and the other using VMWare.

The VMWare virtual server swaps out a large amount of memory despite it having enough RAM to hold MySQL and is correctly configured.

The Xen Virtual machine works just fine and is an identical disk image copy of the VMWare virtual machine. The virtual servers have 8G of RAM and MySQL has 6G allocated to it.

I need to use VMWare though... has any one seen this before?

Details of issue:

VMWare issue:
- The resident set size (RSS) of MySQL is 3.5G bytes.
- MySQL virtual size is 6.7G
.. yet free memory is < 100M and swap in use is >800M

Under Xen:
- Virt memory size 6.7G, RSS is 3.5G
- free memory is about 3G - ie total RAM minus total RSS memory

Both the Xen & VMware VM's:have
- 8G ram
- Red Hat EL 5.2 x86_64
- MySQL 5.1.34
- identical disk copies of each other
- only run MySQL and few essential OS processes that don't use much RAM
- physical server has 32G RAM and only one 8G virtual server

Key settings from VM's:
my.cnf: innodb_buffer_pool_size=6000M
sysctl.conf: vm.swappiness = 0
limits.conf: * soft memlock 7340032 # which is 7G
* hard memlock 7340032

does any one know how to tune VMWare accordingly?


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VMWare & Xen: mysql memory usage differs greatly
November 08, 2009 05:01PM

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