IBM C2B 2.25 Brick On Sled carrier 128-pin HPC - Manual (Page 49)

USER RESPONSIBLE F O R V E R I F Y I N G VERSION A N D COMPLETENESS
O E M F U N C T I O N A L SPECIFICATION ULTRASTAR X P (DFHC) SSA M O D E L S 1.12/2.25 GB - 1.0" H I G H
3.6.5 Save Logs and Pointers
The drive periodically saves data in logs in the reserved area of the disks. The information is used by the
drive to support various commands and for the purpose of failure analysis.
Logs are saved every 35 minutes. The amount of time it takes to update the logs varies depending on the
number of errors since the last update. In most cases, updating those logs and the pointers to those logs will
occur in less than 30 milliseconds.
3.6.6 Disk Sweep
The heads are moved to another area of the disk if the drive has not received a command for at least 40
seconds. After flying in the same spot for 9 minutes, the heads are moved to another position. Execution
time is less than 1 full stroke seek.
3.6.7 Summary
Table 10. Summary of Idle Time Function Performance Impacts
3.7 Command Timeout Limits
The 'Command Timeout Limit' is defined as the time period from when the SCSI_command message is
received by the drive until the corresponding SCSI_status message is transmitted by the drive.
The following times are for environments where Automatic Reallocation is disabled and there are no queued
commands.
Reassignment Time: The drive should be allowed a minimum of 45 seconds to complete a "Reassign
Blocks" command.
Format Time: The time to complete a "Format Unit" command (with Immed bit = 0) varies by model:
C4x 45 minutes
C2x 25 minutes
C1x 15 minutes
Initiators should also use this time to allow format sequences initiated by "Format Unit" commands (with
Immed bit = 1) to compete and place the drive in a "ready for use" state.
Start/Stop Unit Time: The drive should be allowed a minimum of 30 seconds to complete a "Start/Stop
Unit" command (with Immed bit = 0).
Initiators should also use this time to allow start-up sequences initiated by auto start ups and "Start/Stop
Unit" commands (with Immed bit = 1) to complete and place the drive in a "ready for use" state.
Idle Time Function Type Max. Frequency of Occurrence
(minutes)
Duration (ms) Mechanism to Delay/Disable
Servo Run Out 60/(trk/cyl) 100 Re-instruction Period
Servo Bias ( < 1st hour) 12 200 Re-instruction Period
Servo Bias ( > 1st hour) 60 200 Re-instruction Period
P F A 30/(trk/cyl) 80 Re-instruction Period / LITF
Channel Calibration 240 64 Re-instruction Period
Save Logs & Pointers 35 30 Re-instruction Period
Note: "Re-instruction Period" is the time between consecutive SCSI command requests.
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