Cache requirements for open-systems – HP XP Array Manager Software User Manual
Page 12
user data to use Cache Residency. However, RAID-5 or RAID-6 subsystems require three times the
cache size.
Note: If external volumes are used, twice the cache size for the user data is required to use Cache
Residency.
If the priority mode or the bind mode is set, the cache size is calculated assuming that one slot has
the following values.
•
For open-systems volumes:
For OPEN-V, one slot is 264 KB (512 LBAs).
◦
◦
For other than OPEN-V, one slot is 66 KB (128 LBAs).
•
For zSeries and S/390 (3390) volumes:
◦
One slot is 66 KB (128 LBAs).
The calculating procedures for each operation mode and RAID level are described in the following
sections.
Cache Requirements for Open-Systems
To calculate cache size for open-systems:
1.
Calculate the converted values of the starting address and the ending address.
To calculate the converted values of starting address and the ending address for the all specified
LDEVs:
a.
For OPEN-V:
•
Number of LBAs = LDEV size (KB) x 2
Convert the LDEV size to the number of LBAs.
•
Number of slots = (
↑Number of LBAs ÷ 512↑)
Round up the value that is calculated from the formula between the two up-arrows
(
↑) after the decimal point.
•
Converted value of starting address = 0
•
Converted value of ending address = (Number of slots x 512) - 1
b.
For emulation types other than OPEN-V:
•
Number of LBAs = LDEV size (KB) x 2
Convert the LDEV size to the number of LBAs.
•
Number of slots = (
↑Number of LBAs ÷ 96↑)
Round up the value that is calculated from the formula between the two up-arrows
(
↑) after the decimal point.
•
Converted value of ending address = (Number of slots x 96) - 1
•
Converted value of starting address = 0
To calculate the converted values of the starting address and the ending address if the volumes
are specified:
a.
For OPEN-V:
•
Starting value = (
↓Setting value of starting address (LBA) ÷ 512↓)
Round down the value that is calculated from the formula between the two downward
arrows (
↓) after the decimal point.
12
Preparing for Cache Residency Manager Operations