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OEM FUNCTIONAL SPECIFICATION ULTRASTAR XP (DFHC) SSA MODELS 1.12/2.25 GB - 1.0" HIGH
3.0 Performance
Drive performance characteristics are dependent upon the workloads run and the environments in which
they are run.
All times listed in this chapter are typical values provided for information only, so that the performance for
environments and workloads other than those shown as examples can be approximated. Actual minimum
and maximum values will vary depending upon factors such as workload, logical and physical operating envi-
ronments.
3.1 Environment Definition
Drive performance criteria is based on the following operating environment. Deviations from this environ-
ment may cause deviations from values listed in this specification.
Block lengths are formatted at 512 bytes per block.
The number of data buffer cache segments is 8. The total data buffer length is 512k bytes. Each
segment is of equal length. Therefore, each cache segment is 64k bytes.
The number of blocks of customer data that can fit into one segment is reduced because 2 bytes of LRC
information is also stored in the segment for each block of customer data stored in the segment. There-
fore, use the following equation to determine how many blocks can fit into one segment.
(
512KB
# of segments
)
ub/lba +2
Ten byte Read and Write commands are used.
SSA environment consists of a single initiator and single target with no SSA link contention.
The Initiator delay in responding to messages from the Target is assumed to be zero.
All performance enhancing functions are disabled, except where noted. More specifically,
− Commands are not queued
− Caching is disabled (RCD=1, WCE=0)
− Out of order transfers are not allowed (OOTM=0, OOTI=0)
The media is formatted with the skew definition that optimizes the disk data transfer rate for un-
synchronized spindle operation.
All Current Mode Parameters are set to their Default values except where noted.
Averages are based on a sample size of 10,000 operations.
3.2 Workload Definition
The drive's performance criteria is based on the following command workloads. Deviations from these
workloads may cause deviations from this specification.
Operations are either all Reads or all Writes. The specifications for Command Execution Time with
Read Ahead describe exceptions to this restriction. For that scenario all commands are preceded by a
Read command, except for sequential write commands.
The Data Transfer size is set to 64 Blocks.
Source filename=PERFORM IBM Corporation Page 39 of 87