HP StorageWorks SAN Virtualization Services Platform administrator guide (5697-0109, July 2009)

4. At the surviving site, for every failed synchronous mirror group, right-click the mirror group, and
select Manage > Recovery > Force Delete.
The Force Delete option deletes of the synchronous mirror objects on the selected groups. The
local task becomes a simple standalone virtual disk, without permissions, and with PiTs if they
previously existed.
5. Present the virtual disk to the local hosts on the surviving site using the DPM that is online for that
virtual disk.
Re-establishing the connection with the recovered site after Force Delete
1. Make sure that all the components at the recovered site are online except for the DPM that was
deliberately powered off.
2. Make sure that the VSMs at both sites are online and see each other.
3. Turn on the power to the DPM at the recovered site. The DPM at the recovered site joins the system
as a passive DPM.
4. Recreate the synchronous mirror groups that were deleted when you used the Force Delete option.
5. Initiate a resynchronization.
Using ForceActive to recover from failed stretched SVSP domains
HP provides a ForceActive utility on the Virtualization Services Manager CD that can automate the
process of recovery when a stretched domain with two sites has failed. This utility is not installed with
a normal VSM software installation, but is provided as an external utility. Best practice would be to
have a copy of this CD at all sites, so that it can be used with a VSM server at a failed site. To access
this executable, click the Browse to ForceActive Utility link on the opening screen of the Virtualization
Services Manager CD.
This utility is used to recover two operations:
1. The VSM on the surviving site needs to become the active VSM of the domain (if it was passive
before the failure).
2. Access is resumed to the virtual disk data by using the surviving mirror task and the DPM.
By default with the SVSP solution, a passive VSM stops the boot process and opens the recovery tab
in the VSM Monitor if one of the boot disks is missing. VSM also stops the boot process if one of the
synchronous mirror tasks of the setup virtual disks is failed. These are the exact conditions that a
passive VSM would experience if the other site fails. In both cases the VSM waits for approval to
continue the boot process. The VSM waits for the user input because it cannot distinguish between a
split-brain situation caused by broken communication links (both IP and Fibre Channel), where the
other VSM is active and working with a “missing” boot disk, and a real site failure where the other
VSM and missing disk are nonfunctional. A user needs to validate that the second VSM is dead and
allow the surviving VSM to become active despite the missing boot disks by using the interface of the
recovery tab in VSM Monitor.
The ForceActive utility:
• Allows the passive VSM to become active despite missing boot disks (like in the event of site failure).
• Automatically recovers the synchronous mirror group by executing ForceResume. ForceResume
recovers the failed synchronous mirror groups by appointing the surviving DPM as the active DPM
for all failed groups, and makes it expose the data of the surviving mirror task.
• Sends the recovery enablement to the VSM. If the VSM is not ready to accept the command at the
particular time, the utility retries every 5 seconds until the VSM reports that there is an active VSM
for the domain. (While trying to recover from failure, the VSM alternates between stopped and
passive states and will not accept the commands when in a stopped state). If an external application
Synchronous mirroring in a single stretched domain88