UPDATE: Fix released for this 8/2015 – read more here: https://martinsblog.dk/ibmlenovo-storwize-firmware-version-7-6-0-1-released/
Got this from IBM yesterday:
Unfortunately, an issue has been discovered in this release that may lead to unexpected node warmstarts if host I/O is performed to volumes that contain 64,000 extents or more. This may result in both nodes in an I/O group pair warmstarting at the same time, causing a temporary loss of host access to volumes serviced by this I/O group.
We are currently testing a fix for this issue which is expected to be included in the upcoming 22.214.171.124 PTF release.
If you have not yet upgraded to 126.96.36.199:
Before upgrading to 188.8.131.52, ensure that you download the latest version of the upgrade test utility (v17.2) that was uploaded today. This version will check if your system contains any volumes that may be susceptible to this issue and if so will prevent the upgrade from proceeding.
If you have already upgraded to 184.108.40.206:
Depending on the number of extents in your volumes, you may be exposed to this issue. In order to clear this exposure, reboot each node in your cluster one at a time, leaving at least 30 minutes between each reboot to allow time for host multipathing drivers to rediscover paths. Once a node has been rebooted, it will be permanently protected from this issue going forwards.
So wait with the upgrade for 220.127.116.11 😉