Idle Time Functions - IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive Specifications

10.19 Idle Time Functions

10.19.1.1 Automatic Drive Maintenance (ADM)
Enable and disable of A D M function is in control of Mode Page 0, and the shipping default is disable.
A D M function is equipped to enhance the reliability in continuous usage. A D M function is to perform a
CSS automatically after detection of idling time for 1 minute at intervals of 1 week.
Drive response during the CSS by A D M is as follows.
Sense and Inquiry SCSI Commands are executed without delay.
Command other than the above will be completed as quickly as possible (max 10 sec delay over normal
execution time) - if drive is spinning down when command received it will go to spin up immediately.
After completion of the command, then CSS is re-started after detection of idle time for 1 minute.
10.19.1.2 Save Log/PFA Counter
The drive periodically saves data in logs in the reserved area of the disks. The information is used by the
drive to support various SCSI commands and for the purpose of failure analysis. Log/PFA counters are
saved if the drive has not received a SCSI command for 1 hour.
10.19.1.3 Patrol Seek (Forced Seek)
The heads are moved to another area of the disk if the drive has not received a SCSI command for at least
10 minutes. Execution time is less than 1 full stroke seek.
10.19.1.4 Summary
Idle Time Function Period of Occurrence
ADM
Save Log/PFA
Patrol Seek
"Re-instruction Period" is the time between consecutive SCSI command requests.
Figure 136. Summary of Idle Time Functions
Duration
Once a Week 18 sec
After 10 minutes 60 msec
of idle time
After 10 minutes 16 msec
of idle time
Method to Disable
DADM (Mode page 0)
Re-instruction Period
DEXCPT (Mode page 1C)
Re-instruction Period
Re-instruction Period
Additional Information
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