Chapter 4. Initial configuration 125
/SM590000Unmounting all file systems that were created on IBM Spectrum Virtualize volumes (for file 
systems created directly on IBM Spectrum Virtualize volumes) or bringing offline all logical 
volume groups by using volumes that are presented by the IBM Spectrum Virtualize 
system.
/SM590000Accepting loss of access to storage for volumes that are mirrored at the operating system 
level.
For volumes that are mirrored at the operating system level, loss of one of the data copies 
triggers errors in the operating system and causes a loss of redundancy because the data 
copies go out of sync.
Before shutting down the system, ensure that you stopped all FlashCopy mappings, remote 
copy relationships, data migration operations, and forced deletions.
Storwize V7000 control enclosures contain batteries that provide backup power to the system 
to protect against unforeseen loss of power. When AC power to the enclosure is interrupted 
for more than approximately 10 seconds, the system starts system state dump procedure, 
which includes saving cached data to an internal drive. 
When the process to save critical data starts, the system stops handling I/O requests from the 
host applications, and Metro Mirror and Global Mirror relationships go offline. The system 
powers off when the saving of the critical data completes. If AC power is restored after the 
system state dump starts, the dump continues to completion. The system then restarts.
In a fully redundant system with two batteries and two canisters, there is enough charge in the 
batteries to support saving critical data from both canisters to a local drive twice. In a system 
with a failed battery, there is enough charge in the remaining battery to support saving critical 
data from both canisters to a local drive once.
If both node canisters shut down without writing the cache and state data to the local drive, 
the system is unable to restart without an extended service action. The system configuration 
must be restored. If any cache write data is lost, volumes must be restored from a backup. 
Therefore, it is important not to remove the canisters or the power supply units from the 
control enclosures unless directed to do so by the service procedures. Removing either of 
these components might prevent the node canister from writing its cache and state data to 
the local drive.
In case of an imminent power loss, strive to shut down the system cleanly, without triggering 
the data dump procedure. This process preserves battery charges for actual emergencies. 
When the AC power is restored after a power outage that causes both canisters to save their 
critical data, the system restarts only when the batteries have sufficient charge to power both 
canisters for the duration of saving the critical data again. 
Note: Some applications (for example, databases), can use a volume that is not mounted 
as a file system. Make sure that no volumes that are presented by the IBM Spectrum 
Virtualize are in use on a host if you want to shut down the storage system but not the host.
Note: Storwize V7000 expansion canisters do not cache volume data or store state 
information in volatile memory. Therefore, they do not require battery power. If AC power to 
both power supplies in an expansion enclosure fails, the enclosure powers off. When AC 
power is restored to at least one of the power supplies, the controller restarts without 
operator intervention.