Xsan: Best practices for data integrity

These suggested guidelines for deploying Xsan help to ensure consistent access to data stored on Xsan volumes.
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Deploy a backup solution

There are many means of backing up data, including hardware solutions and software solutions. The backup process may be as simple as a drag and drop of vital files to a local or network volume or may be as complex as using a software solution that backs up data to a hardware solution, such as a tape library or Disk Array, on a schedule. For more information on backup solutions, please contact your Apple Sales Representative.

Ensure that power is not interrupted

Use an Uninterruptable Power Supply (UPS) to ensure that all SAN components remain available during power outages.

Configure for optimal performance

Follow the separate list of tips for optimal performance.

Check enclosure locks

If using Xserves in the Xsan deployment, ensure that the Xserve's enclosure locks are engaged. Doing so will ensure that startup drives are not unmounted when releasing the drive handle on the Xserve Drive Modules. For instructions on how to engage the enclosure locks on your Xserve, see the Xserve product manual specific to the model of Xserve being used.

Config file backup

Each time you change Xsan configuration options, such as creating a new volume or promoting a client to an MDC, back up /Library/Filesystems/Xsan/config to an external volume.

Use latest Xsan software

Use Software Update regularly to ensure that the most recent version of Xsan is installed.

Check fibre channel switch firmware

Ensure that your fibre channel switch is running a supported version of firmware. For QLogic firmware, please review the versions tested by Apple.

Unmount and Stop Xsan volumes before rebooting targets

Before shutting down or rebooting storage devices, unmount and stop any Xsan Volumes that include LUNs which correspond to arrays hosted on the targets that are to be restarted. Certain administrative changes will result in Storage Devices restarting. Promise VTrak RAID controllers will restart when its firmware is updated. The Xserve RAID will restart if any of the following settings are configured:

RAID Admin > Create Array 
RAID Admin > Delete Array 
RAID Admin > Settings > System 
RAID Admin > Settings > Network 
RAID Admin > Settings > Fibre Channel 
RAID Admin > Advanced > Slicing 
RAID Admin > Advanced > LUN Masking

Also, avoid performing changes in RAID Admin > Advanced > Expansion that will delete a pre-existing array if the array is acting as a LUN that has been incorporated into the Xsan Volume.

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