Citrix Systems 6 manual Upgrading LVM Storage from XenServer 5.0 or Earlier, VDI Types

There are two basic steps involved in creating a new storage repository for use on a XenServer host using the CLI:

1.Probe the SR type to determine values for any required parameters.

2.Create the SR to initialize the SR object and associated PBD objects, plug the PBDs, and activate the SR.

These steps differ in detail depending on the type of SR being created. In all examples the sr-createcommand returns the UUID of the created SR if successful.

SRs can also be destroyed when no longer in use to free up the physical device, or forgotten to detach the SR from one XenServer host and attach it to another. See the section called “Destroying or Forgetting a SR” for details.

Note:

When specifying StorageLink configuration for a XenServer host or pool, supply either the default credentials of username: admin and password: storagelink, or any custom credentials specified during installation of the StorageLink Gateway service. Unlike StorageLink Manager, XenCenter does not supply the default credentials automatically.

Upgrading LVM Storage from XenServer 5.0 or Earlier

See the XenServer Installation Guide for information on upgrading LVM storage to enable the latest features. Local, LVM on iSCSI, and LVM on HBA storage types from older (XenServer 5.0 and before) product versions will need to be upgraded before they will support snapshot and fast clone.

Warning:

SR upgrade of SRs created in version 5.0 or before requires the creation of a 4MB metadata volume. Please ensure that there are at least 4MB of free space on your SR before attempting to upgrade the storage.

Note:

Upgrade is a one-way operation so Citrix recommends only performing the upgrade when you are certain the storage will no longer need to be attached to a pool running an older software version.

LVM Performance Considerations

The snapshot and fast clone functionality provided in XenServer 5.5 and later for LVM-based SRs comes with an inherent performance overhead. In cases where optimal performance is desired, XenServer supports creation of VDIs in the raw format in addition to the default VHD format. The XenServer snapshot functionality is not supported on raw VDIs.

Note:

Non-transportable snapshots using the default Windows VSS provider will work on any type of VDI.

Warning:

Do not try to snapshot a VM that has type=raw disks attached. This could result in a partial snapshot being created. In this situation, you can identify the orphan snapshot VDIs by checking the snapshot-offield and then deleting them.

VDI Types

In general, VHD format VDIs will be created. You can opt to use raw at the time you create the VDI; this can only be done using the xe CLI. After software upgrade from a previous XenServer version, existing data will be preserved as backwards-compatible raw VDIs but these are special-cased so that snapshots can be taken of them once you have allowed this by upgrading the SR. Once the SR has been upgraded and the first snapshot has been taken, you will be accessing the data through a VHD format VDI.

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