ESX Partition

Partitions let you segment a physical drive into separate logical drives. Partitions are treated as independent disks with their own defined sizes and are assigned mount points so that they can be accessed from the default root partition. Partitions are used to ensure that unchecked log growth does not affect other critical operating system partitions. The default partitions on a Linux system are the /boot partition which stores files used to boot the computer, and the / partition which is the root partition from which all mount points derive. The additional partitions that ESX uses are set to mount automatically when the server boots up, so they are accessible from the root partition.

When you install ESX you have the option to use the default partition sizes or specify your own partitions. The default sizes will typically work for many environments, but there are changes you can make to ensure that you do not run into problems later if your partitions run out of space or you try to increase the memory allocated to the Service Console. First, let’s cover what partitions are created by default. ESX hosts have required and optional partitions: /boot and vmkcore are physical partitions; /, swap, /var/log, and all the optional partitions are stored on a virtual disk called esxconsole–<system–uuid>/esxconsole.vmdk. The virtual disk is stored in a VMFS volume. The following partitions are required.

• /boot—This is the boot partition that contains files used to boot the ESX server. The ESX boot disk requires 1.25GB of free space and includes the /boot and vmkcore partitions. The /boot partition alone requires 1100MB; the extra space is used for the vmkcore partition.

• /—This is the root partition that contains the ESX server operating system files. It is calculated dynamically based on the size of the /usr partition. By default, the minimum size is 5GB and no /usr partition is defined.

• swap—This partition does not have a mount point and is used by the Service Console as swap space for virtual memory. By default, this partition is 600MB.

• /var/log—This partition is where the ESX server logfiles are stored. By default, this partition is 2GB.

• vmkcore—This partition serves as a repository for vmkernel core dump files in the event that a core dump occurs. By default, this partition is 100MB and is part of the /boot partition.

• vmfs—The remaining free space after all the other partitions are created on the drive on which ESX is installed is used to create a VMFS volume. The VMFS volume also holds the esxconsole.vmdk file.

With the default partition sizes, the total Service Console size is 7.6GB. You cannot define the sizes of the /boot, vmkcore, and /vmfs partitions when you use the graphical or text installation modes. The following changes are recommended for the default partitions.

• /boot—This partition cannot be changed.

• /—It is okay to leave the root partition at 5GB.

• swap—Change this from 600MB to 1600MB. This should be twice the amount of memory that is dedicated to the Service Console. The default amount of memory typically devoted to the Service Console is 358MB. However, if the host has limited physical memory, the memory devoted to the Service Console is 300MB, which is why the default swap size is 600MB. The recommended amount of memory for the Service Console is a maximum of 800MB, which would require a 1600MB swap partition.

• /var/log—Change this from 2GB to 5GB to allow for extra space for logfiles.

• vmkcore—This partition cannot be changed.

• vmfs—This will be created using the remaining disk space on the physical disk and cannot be changed.

The extra /home, /tmp, /var, and /opt partitions are normally folders created in the / partition. By creating separate partitions for them, you ensure that they will not fill up and negatively impact the critical / partition.

• /home—Create a partition of 2GB for any home directories that are created for local users on the ESX host.

• /tmp—Create a partition of 2GB for the directory that is used to store temporary files.

• /var—Create a partition of 4GB for the directory that is used to hold administrative log and configuration files.

• /opt—Create a partition of 2GB for the directory that is used for logging of the HA feature.

Using these custom partition sizes, the total disk space used by the Service Console is about 19GB. It is highly recommended that you use custom partitions, as once you install ESX with the default partition sizes, it is very difficult to change them later on. Taking a little bit of extra time and disk space when doing your initial configuration can help you avoid problems that you might experience later. We will cover how to make these changes during the ESX installation steps momentarily. Table 11.3 provides a summary of the default sizes compared to the recommended partition size changes.