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may leverage space efficiency and will not tie up XenServer host resources. The downside to this
process is that although a unique iSCSI volume will be created with duplicated data, the UUIDs of
both the storage repository and virtual disk will also be duplicated.
Any host seen by XenCenter, including a resource pool, must not share storage repositories or virtual
disks with duplicate UUIDs. This management layer depends upon uniqueness. Storage with duplicate
UUIDs will not be allowed and can’t be used; only the first unique UUID is seen. Therefore, a step
process must be followed to force the uniqueness of the SR and virtual disk, which will allow it to be
seen and used.
For this example, the system prepared XPSP2-02 VM will be used as the source. This VM is stored on
a virtual disk on the XPSP2-02 storage repository. The VM is shut down. Open the HP StorageWorks
Centralized Management Console (CMC), select the iSCSI volume
XPSP2-02
. Select
New Remote
Snapshot
as this will create a duplicated volume copy on the SAN. Create the new Primary Snapshot.
Note the default name
XPSP2-02_SS_1
. Select the Same Management Group
HP-Boulder
, select new
remote volume on the existing cluster, adding a volume to the existing cluster. Select the existing
cluster IT-DataCenter
and provide a new volume name
XPSP2-02-RS-1
with appropriate replication
levels (2-Way for this example). The new volume will now replicate from snapshot to snapshot and
this operation occurs from within the SAN. Progress of the replicated volume may be seen on the
volume’s Remote Snapshots tab under the “% Complete” column. Note that this new volume XPSP2-
02-RS-1 is a remote volume type and may not be used until the volume is made primary. As a remote
volume type, it will be grayed out.
To use the volume, highlight the new volume
XPSP2-02-RS-1
, right click on the volume and select
edit
volume
. On the Advanced tab, change the volume type from
Remot
e to
Primary
. In this example,
Thin
Provisioning
is also checked. On the basic tab, select
Assign and Unassign Servers
. Ensure that all
XenServer Hosts in the resource pool are assigned read/write access to the volume. In the CMC,
highlight the
XPSP2-02-RS-1_RS_1
remote snapshot, right click on that snapshot and select
Delete
Snapshot
. A stand-alone primary iSCSI volume, XPSP2-02-RS-1 now exists, which is a complete copy
of the original XPSP2-02 volume, data, storage repository, virtual disk, and UUIDs in all.
Since only one unique UUID may be present, the choice of either forgetting the current XPSP2-02
storage repository and changing the new XPSP2-02-RS-1 repository and reattaching to the original, or
changing the original XPSP2-02 repository and then re-attaching the new XPSP2-02-RS-1 must be
made. In this example, detach and forget the original SR keeping its original UUID.
Step 1 -
In the XenCenter Console, power down the XPSP2-02 VM. Highlight the XPSP2-02 storage
repository, right click and select
Detach Storage Repository
. Select
Yes
that you want to detach this
storage repository. Highlight the XPSP2-02 detached storage repository, right click and select
Forget
Storage Repository
. Select
Yes
that you want to forget this storage repository. Note that the XPSP2-02
storage repository is now not listed in XenCenter.
Step 2 –
In the XenCenter Console, select
New Storage
. Select the iSCSI Virtual disk storage type.
Enter the iSCSI storage name XPSP2-02-RS-1, the iSCSI target portal, and select
Discover IQNs
. Select
the
XPSP2-02-RS-1 iSCSI
volume. Select
Discover LUNs
and
Finish
. Select
Reattach
to preserve the
existing data from the replication. Do not select format; otherwise, the VM and data on the volume
will be lost. The XPSP2-02-RS-1 volume will now be attached and seen to the XenServer resource pool.
Step 3 –
Open up a XenServer console in XenCenter. The XPSP2-02-RS-1 storage repository mapped
device path must be found to change its UUID. On the console command line, type:
ls –las /dev/disk/by-path | grep –i “XPSP2-02-RS-1”
This command will list all the devices by path and pipe the output to grep, searching without case
sensitivity for the XPSP2-02-RS-1 volume which will be found in the IQN path. In this example, the
device path is /dev/disk/by-path/ip-1.1.1.225:3260-iscsi-iqn.2003-10.com.lefthandnetworks:hp-
boulder:285:xpsp2-02-rs-1 as link resolving to /dev/sdd (/dev/disk/by-path/../../sdd). The
