HP XP P9500 Owner's Manual page 46

Table 1 1 System option modes (continued)
Mode Category
896 Thin Provisioning
Thin Provisioning
Z,
Smart Tiers
Smart Tiers Z, Fast
Snap
897 Smart Tiers, Smart
Tiers Z
46 Functional and operational characteristics
Description
Notes:
1. To apply the mode, set the RMF version of mainframe to be
connected to 1.12 or higher.
2. If the OS does not use a supported version, the transfer speed
cannot be displayed correctly.
The mode enables or disables the background format function
performed on an unformatted area of a THP/Smart pool.
For the information of operating conditions, refer to Provisioning
Guide for Open Systems or Provisioning Guide for Mainframe
Systems.
Mode 896 = ON:
The background format function is enabled.
Mode 896 = OFF (default):
The background format function is disabled.
Note:
1. The mode is applied when a customer requires the background
format for a DP/Smart pool in the environment where new
page allocation (for example, when system files are created
from a host for newly created multiple THP VOLs), frequently
occurs and the write performance degrades because of an
increase in write pending rate.
2. When the mode is set to ON, because up to 42MB/s of ECCG
performance is used, local copy performance may degrade
by about 10%. Therefore, confirm whether the 10%
performance degradation is acceptable or not before setting
the mode to ON.
3. When a Dynamic Provisioning VOL that is used as an external
VOL is used as a pool VOL, if the external pool becomes full
due to the background format, the external VOL may be
blocked.
If the external pool capacity is smaller than the external VOL
(Dynamic Provisioning VOL), do not set the mode to ON.
By the combination of SOM 897 and 898 setting, the expansion
width of Tier Range upper I/O value (IOPH) can be changed as
follows.
Mode 897 = ON:
SOM 898 is OFF: 1 10%+0IO
SOM 898 is ON: 1 10%+2IO
Mode 897 = OFF (Default)
SOM 898 is OFF: 1 10%+5IO (Default)
SOM 898 is ON: 1 10%+1IO
By setting the SOM s to ON to lower the upper limit for each tier,
the gray zone between other tiers becomes narrow and the
frequency of page allocation increases.
Notes:
1. Apply the mode when the usage of upper tier is low and that
of lower tier is high.
2. The mode must be used with SOM 898.
3. Narrowing the gray zone increases the number of pages to
migrate between tiers per relocation.
4. When Tier1 is SSD while SOM 901 is set to ON, the effect
of SOM 897 and 898 to the gray zone of Tire1 and Tier2 is
disabled and the SOM 901 setting is enabled instead. In
Default MCU/RCU
OFF ..
OFF ..