System information
Use Disk Shares to Prioritize Virtual Machines
If multiple virtual machines access the same VMFS datastore (and therefore the same LUN), use disk shares
to prioritize the disk accesses from the virtual machines. Disk shares distinguish high-priority from low-
priority virtual machines.
Procedure
1 Start a vSphere Client and connect to vCenter Server.
2 Select the virtual machine in the inventory panel and click Edit virtual machine settings from the menu.
3 Click the Resources tab and click Disk.
4 Double-click the Shares column for the disk to modify and select the required value from the drop-down
menu.
Shares is a value that represents the relative metric for controlling disk bandwidth to all virtual machines.
The values Low, Normal, High, and Custom are compared to the sum of all shares of all virtual machines
on the server and, on an ESX host, the service console. Share allocation symbolic values can be used to
configure their conversion into numeric values.
5 Click OK to save your selection.
NOTE Disk shares are relevant only within a given ESX/ESXi host. The shares assigned to virtual machines on
one host have no effect on virtual machines on other hosts.
Specifics of Using SAN Storage with ESX/ESXi
Using a SAN in conjunction with an ESX/ESXi host differs from traditional SAN usage in a variety of ways.
When you use SAN storage with ESX/ESXi, keep in mind the following considerations:
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You cannot directly access the virtual machine operating system that uses the storage. With traditional
tools, you can monitor only the VMware ESX/ESXi operating system. You use the vSphere Client to
monitor virtual machines.
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When you create a virtual machine, it is, by default, configured with one virtual hard disk and one virtual
SCSI controller. You can modify the SCSI controller type and SCSI bus sharing characteristics by using
the vSphere Client to edit the virtual machine settings. You can also add hard disks to your virtual machine.
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The HBA visible to the SAN administration tools is part of the ESX/ESXi system, not part of the virtual
machine.
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Your ESX/ESXi system performs multipathing for you.
Third-Party Management Applications
You can use third-party management applications in conjunction with your ESX/ESXi host.
Most SAN hardware is packaged with SAN management software. This software typically runs on the storage
array or on a single server, independent of the servers that use the SAN for storage.
Use this third-party management software for the following tasks:
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Storage array management, including LUN creation, array cache management, LUN mapping, and LUN
security.
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Setting up replication, check points, snapshots, or mirroring.
Chapter 2 Using ESX/ESXi with Fibre Channel SAN
VMware, Inc. 21