To enhance performance, install or upgrade ESXi on a robust system with more RAM than the minimum required and with multiple physical disks.

For ESXi system requirements, see ESXi Hardware Requirements.

Table 1. Recommendations for Enhanced Performance
System Element Recommendation
RAM ESXi hosts require more RAM than typical servers. ESXi 8.0 requires a minimum of 8 GB of physical RAM. Provide at least 12 GB of RAM to take full advantage of ESXi features and run virtual machines in typical production environments. An ESXi host must have sufficient RAM to run concurrent virtual machines. The following examples are provided to help you calculate the RAM required by the virtual machines running on the ESXi host.

Operating four virtual machines with Red Hat Enterprise Linux or Windows XP requires at least 3 GB of RAM for baseline performance. This figure includes 1024 MB for the virtual machines, 256 MB minimum for each operating system as recommended by vendors.

Running these four virtual machines with 512 MB RAM requires that the ESXi host have 4 GB RAM, which includes 2048 MB for the virtual machines.

These calculations do not include possible memory savings from using variable overhead memory for each virtual machine. See vSphere Resource Management.

Dedicated Fast Ethernet adapters for virtual machines Place the management network and virtual machine networks on different physical network cards. Dedicated Gigabit Ethernet cards for virtual machines, such as Intel PRO 1000 adapters, improve throughput to virtual machines with high network traffic.
Disk location Place all data that your virtual machines use on physical disks allocated specifically to virtual machines. Performance is better when you do not place your virtual machines on the disk containing the ESXi boot image. Use physical disks that are large enough to hold disk images that all the virtual machines use.
VMFS6 partitioning The ESXi installer creates the initial VMFS volumes on the first blank local disk found. To add disks or modify the original configuration, use the vSphere Client. This practice ensures that the starting sectors of partitions are 64K-aligned, which improves storage performance.
Note: For SAS-only environments, the installer might not format the disks. For some SAS disks, it is not possible to identify whether the disks are local or remote. After the installation, you can use the vSphere Client to set up VMFS.
Processors Faster processors improve ESXi performance. For certain workloads, larger caches improve ESXi performance.
Hardware compatibility Use devices in your server that are supported by ESXi drivers. See the Hardware Compatibility Guide at http://www.vmware.com/resources/compatibility.