Internal Magnetic Media
344 AS/400e System Handbook
Integrated Hardware Disk Compression
Data is dynamically compressed or uncompressed by the DASD controller as data is written
to and read from disk. Disk compression has no affect on the main CPU utilization since
compression is performed by the DASD controller input/output processor (IOP).
Support for Integrated Hardware Disk Compression is provided by DASD controllers #2741,
#2748, #4748/#9748, #6533, and CCIN 671A MFIOP. Compression is limited to user ASPs.
The compression ratio results of DASD varies. The compression ratio achieved and the
impact on DASD performance depends on the data and how it is accessed.
Disk Model Identifier
The system configuration list (rack configuration) shows the disk type and model in the format
XXXX-YYY, where the
XXXX
identifies the CCIN number of the disk and
YYY
identifies the
potential or actual disk protection and compression. Refer to the CCIN chapter of the
AS/400e System Builder
, SG24-2155, for a listing of the AS/400 CCIN numbres. The YYY
identifiers are:
• 030: Unprotected or mirrored unit attached to a non-RAID capable controller.
• 050: Unprotected or mirrored unit attached to a RAID capable controller.
• 060: Unprotected or mirrored unit attached to a RAID capable controller. Data
compression is active.
• 070: Non-parity member of a parity (RAID) set. Full capacity. Data compression is
inactive.
• 072: Parity member of a parity (RAID) set with eight parity members. Seven-eighths
capacity. Data compression is inactive.
• 074: Parity member of a parity (RAID) set with four parity members. Three-fourths
capacity. Data compression is inactive.
• 080: Non-parity member of a parity (RAID) set. Full capacity. Data compression is
active.
• 082: Parity member of a parity (RAID) set with eight parity members. Seven-eighths
capacity. Data compression is active.
• 084: Parity member of a parity (RAID) set with four parity members. Three-fourths
capacity. Compression is active.
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