Yesterday VMware released Update 4 for ESX 3.5 and ESXi 3.5. It includes a few new features but no major enhancements. It also has some limitations to go with it that are important to note.
Here are some of the highlights:
- ESX 3.5 U4 does not work with all versions of vCenter 2.5. For example, you will need to have vCenter updated to at least Update 3 in order to be able to use it to manage ESX 3.5 Update 4. There is a compatibility matrix of which versions of ESX work with specific versions of vCenter here (this link opens a PDF).
- You can now enable the Enhanced vmxnet driver for 32-bit operating systems. Previously you had to set the guest OS to a supported type (like Server 2003 x64), enable the Enhanced vmxnet NIC, and then change the OS back. This is no longer required. This driver enables advanced networking features like TCP Segmentation Offload.
- VMware has included experimental support for PXE booting ESXi hosts. This would allow you to have a completely stateless and diskless server with ESXi installed on a flash drive able to PXE boot and be ready to host virtual machines in minutes.
- A large number of new hardware devices are supported, including NICs, SATA controllers, etc.
The full release notes can be found here for ESX 3.5 and here for ESXi 3.5.
As with any update to ESX, make sure you do it in the proper order. First upgrade vCenter and your database and then update each of your hosts.