Managing Battery Issues; Replacing Adapters (Hba) And Storage Controllers - IBM Midrange System DS4000 Series Hardware Manual

A flash-based SSD has a limited wear life before individual memory locations can no longer
reliably persist data. The disk drive continuously monitors itself and reports its wear life status
to the controller. Two mechanisms exist to alert you that an SSD is nearing the end of its
useful life: average erase count and spare blocks remaining. You can find these two pieces of
information in the disk drive properties, which you can see in the storage management
software by selecting a disk drive on the Physical tab.
The average erase count is reported as a percentage of the rated lifetime. When the average
erase count reaches 80 percent, an informational event is logged to the Major Event Log
(MEL). At this time, schedule the replacement of the SSD. When the average erase count
reaches 90 percent, a critical event is logged, and a Needs Attention condition occurs. At this
time, replace the SSD as soon as possible.
The spare blocks remaining are reported as a percentage of the total blocks. When the spare
blocks remaining falls below 20 percent, an informational event is logged to the MEL. At this
time, schedule the replacement of the SSD. When the spare blocks remaining falls below 10
percent, a critical event is logged, and a Needs Attention condition occurs. At this time,
replace the SSD as soon as possible.

7.9.4 Managing battery issues

On DS5000 storage subsystems, the battery unit contains lithium-ion battery packs that can
maintain power to the RAID controller caches for up to thirty minutes to flush cache memory
to flash memory modules in the event of a power loss.
This battery unit provides backup power to each controller's cache memory. Each battery unit
contains a sealed, rechargeable lithium-ion battery. The battery unit can maintain data in the
cache for three days.
On both the DS4000 and DS5000 storage subsystems, the battery should not be replaced
until it is marked failed by the controller. If the batteries are shown as expired, use the reset
battery age function in the Storage Manager Subsystem Management window to reset the
age.

7.10 Replacing adapters (HBA) and storage controllers

The logical volumes created in the DS5000 are mapped to the host's Fibre Channel adapter's
worldwide name (WWN). Replacing an HBA affects the mappings in both the DS4000 and the
SAN zoning configuration if the HBAs are not directly attached.
Consider the following items:
Host adapter replacement
If for any reason an HBA is replaced and you are not using the default group to map your
logical volumes in the DS5000, you will not see any disks through the new controller until
the mappings are regenerated by replacing the old HBA WWPN with the new adapter
WWPN.
Also, update your SAN zoning configuration after changing the HBA to allow the new
WWPN to communicate with the target DS5000.
Chapter 7. Advanced maintenance, troubleshooting, and diagnostics
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