Avago Technologies Syncro 9361-8i - Manual (Page 74)

Avago Technologies
- 74 -
Syncro CS 9361-8i and Syncro CS 9380-8e Solution User Guide 
October 2014
Chapter 4: Troubleshooting
Handling Pinned Cache on Both Nodes
4.3 Handling Pinned Cache on Both Nodes
This section describes a scenario in which pinned cache occurs and it describes how to handle the pinned cache. If
you remove drives or if both the nodes and the attached expanders/enclosures power down abruptly, pinned cache
can result. Pinned cache is data that could not be flushed to the drives because of the drive removal or power outage.
The following table describes a scenario with pinned cache and offers a solution.
Table 1 Pinned Cache Scenario and Solution
Scenario Solution
 While running I/Os on a Syncro CS configuration, you remove drives or
both the nodes and the attached expander/enclosure power down
abruptly.
 These actions result in pinned data. which is data that the storage
controller cannot remove from cache. The pinned cache is generated on
both nodes, which the BIOS reports. The previously configured VDs go
offline.
 When the system reboots, if you reinsert the drives and the virtual drives
(VD) can be rebuilt, the firmware automatically flushes the pinned data to
the drives. However, if the firmware does not find the drives, the firmware
lets you decide what to do with the pinned data.
 Next, both nodes are powered up but the expanders are not. The BIOS on
both nodes waits for you to enter the CTRL-R utility. You can the utility to
discard the pinned cache or to bring the previous configured VDs online
and flush the pinned cache to the drives for one node (in this example,
node 1).
 After you discard the pinned cache or flush the pinned cache on node 1,
the firmware performs the same action automatically on node 2 (the node
still waiting for you to enter the CTRL-R utility).
 Node 2 is notified that the pinned cache on node 1 has been cleared, so it
can also clear its own pinned cache. However, the firmware on node 2
cannot communicate to the BIOS that its cache has been cleared.
 Node 2 continues to wait on the pinned cache BIOS message (even after
node 2 has cleared its pinned cache) and to operate in pre-boot
environment. Node 2 does not boot until you intervene.
 Operating node 2 in pre-boot environment affects the HA functionality
because you cannot perform any fail-overs on this node. In addition, it can
result in firmware failure.
The only solution is to intervene on both nodes. Use the CTRL-R
utility to clear the pinned cache or restore the VDs and flush the
pinned cache to the drives for one node.
Next, enter the CTRL-R utility on the other node to clear the
pinned cache or restore the VDs and flush the pinned cache to
the drives for the other node. These actions allow the firmware
on both nodes to proceed.
This behavior is essentially the legacy MegaRAID behavior; only
now, you need to use the CTRL-R utility to allow the firmware to
proceed on both nodes.