Shared Memory; Flash Storage Chassis; P9000 Flash Module - HP XP P9500 Owner's Manual

Shared memory

The P9500 shared memory is not on a separate memory module as it was in the previous hardware
systems. Shared memory resides by default on the first pair of cache boards in controller chassis
#0.
When you install software features such as Snapshot or Continuous Access Journal, the shared
memory usage increases as software features are installed. Shared memory can use up to 56 GB.
Depending on how much cache memory is installed, it may be necessary to install more cache
memory as more software features are installed in the system. Up to 32 GB can be installed on
each cache board. When 32 GB of cache is installed, it is also necessary to install a second SSD
(cache flash memory) on the cache board to back up the cache in case of power failure. Additional
cache backup SSD memory comes in 32 and 64 GB capacities.
In addition to cache, the shared memory on each cache board contains a 1/2 GB cache directory
to safeguard write pending data in the cache in the unlikely case of double failure of the shared
memory cache area. The cache directory has mapping tables for the Micro Processor Blade LDEVs
and the allocated cache slots in each Micro Processor Blade cache partition.
NOTE: Shared Memory in the P9000 is not a separate memory module as it was in the HP
XP24000/20000 disk arrays.

Flash storage chassis

This section includes information on the flash module drive (FMD), flash storage unit (FSU), and
flash storage chassis (FSX).

P9000 flash module

The P9000 flash module is a custom-designed and manufactured enterprise class solid state storage
module. It uses a high performance, custom ASIC flash controller and standard flash memory chips
in an implementation that exceeds the performance of expensive SLC SSDs, but costs less than less
expensive MLC SSDs. The FMD greatly improves the performance and solid state storage capacity
of the VSP system, while significantly reducing the cost per TB of storage.
Even in the initial capacity of 1.6 TB per FMD, the FMD outperforms both MLC and SLC flash
drives, has a longer service life, requires less power, and generates less heat per TB than SSDs.
FMDs can be used instead of, or in addition to, disk and flash drives, but they are installed in a
flash storage "chassis" composed of a cluster four flash module units (FMU). The next section
describes the FMU.
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