UCS SAN BOOT [Explained & Configuration]

SAN Boot

You can configure a boot policy to boot one or more servers from an operating system image on the SAN. The boot policy can include a primary and a secondary SAN boot. If the primary boot fails, the server attempts to boot from the secondary.

Cisco recommends using a SAN boot, because it offers the most service profile mobility within the system. If you boot from the SAN when you move a service profile from one server to another, the new server boots from the same operating system image. Therefore, the new server appears as the same server to the network.

To use a SAN boot, ensure that the following is configured:

  • The Cisco UCS domain must be able to communicate with the SAN storage device that hosts the operating system image.
  • A boot target LUN (Logical Unit Number) on the device where the operating system image is located.

Configuring a SAN Boot for a Boot Policy

You can also create a local boot policy that is restricted to a service profile or service profile template. However, Cisco recommends that you create a global boot policy that can be included in multiple service profiles or service profile templates.


Step 1Click the down arrows to expand the vHBAs area.
Step 2Click the Add SAN Boot link.
Step 3In the Add San Boot dialog box, specify the vHBA and type, then click OK.You can specify a Primary or a Secondary SAN boot. If the primary boot fails, the server attempts to boot from the secondary. The Any option is for unsupported adapters that connect directly to the SAN storage device and bypasses UCS Manager. Do not use the Any option with SAN boot for a supported set of adaptors which are managed by UCSM. For unsupported adaptors, use the instructions from the vendor to configure the adaptor for booting.
Step 4If this vHBA points to a bootable SAN image, click the Add SAN Boot Target link and, in the Add SAN Boot Target dialog box, specify the boot target LUN, boot target WWPN, and type, then click OK:
Step 5Do one of the following:Add another boot device to the Boot Order table.Click OK to finish.

Then, Include the boot policy in a service profile and template.

After a server is associated with a service profile that includes this boot policy, you can verify the actual boot order in the Boot Order Details area on the General tab for the server.


If you configure a local disk and a SAN LUN for the boot order storage type and the operating system or logical volume manager (LVM) is configured incorrectly, the server might boot from the local disk rather than the SAN LUN.

For example, on a server with Red Hat Linux installed, where the LVM is configured with default LV names and the boot order is configured with a SAN LUN and a local disk, Linux reports that there are two LVs with the same name and boots from the LV with the lowest SCSI ID, which could be the local disk.


Above are notes from following Cisco White paper documentation:



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