Notice from VMware:

The 2.5.4 patch 6 (Build #41630) and 2.5.3 patch 9 (Build #41618) has been recalled in the interest of stability for ESX servers.

In an environment where Windows and Linux virtual machines are configured with vmxnet virtual NIC driver, when the virtual machine is either powered off, suspended or migrated live via VMotion to another host, a small amount of memory is not freed. Hence, multiple virtual machine power-offs, suspensions and VMotions may cause the host to run low on memory.

A replacement patch which fixes this issue will be released within a few days and posted to the same page as the original patch:

ESX 2.5.3 Patch Download Page
http://www.vmware.com/support/esx25/doc/esx-253-200703-patch.html

ESX 2.5.4 Patch Download Page
http://www.vmware.com/support/esx25/doc/esx-254-200703-patch.html

Workarounds:

Minimize virtual machine power-offs, suspensions and VMotion on servers running 2.5.4 patch 6 (Build #41630) and 2.5.3 patch 9 (Build #41618) until a new patch is available.

If this patch has already been applied to your system and your host is running low on memory resulting in the inability to power on virtual machines, a possible workaround would be to cold migrate the virtual machine to another ESX host with sufficient memory.

If the virtual machine must be started on the same ESX host, possible workarounds include:

• Migrating all the virtual machines to another host using VMotion, rebooting the host, and migrating the virtual machines back to the original host
• Powering off/suspending the virtual machines, rebooting the host and powering on/resuming the virtual machines