To enhance performance, VMware recommends that you install ESXi on a robust system with more RAM than the minimum required and with multiple physical disks.

Consider the following recommendations for enhanced performance:

RAM – ESXi 4.1 hosts require more RAM than typical servers. An ESXi 4.1 host must be equipped with sufficient RAM to run concurrent virtual machines.

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

Running these four virtual machines with 512MB RAM requires that the ESXi 4.1 host be equipped with approximately 4GB RAM, which includes 2048MB for the virtual machines.

These calculations do not take into account possible memory savings from using variable overhead memory for each virtual machine. See the Resource Management Guide.

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 used by your virtual machines 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 4.1 Installable boot image. Use physical disks that are large enough to hold disk images used by all the virtual machines.

VMFS3 partitioning – The ESXi 4.1 installer creates the initial VMFS volumes automatically on blank local disks. To add disks or modify the original configuration, use the vSphere Client. This application ensures that the starting sectors of partitions are 64K-aligned, which improves storage performance.


For SAS-only environments, the installer might not format the disks. For some SAS disks, it is difficult 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 4.1 performance. For certain workloads, larger caches improve ESXi 4.1 performance.

Hardware compatibility – Use devices in your server that are supported by ESXi 4.1 drivers. See the Hardware Compatibility Guide at