SCF Reference Manual for the Storage Subsystem (G06.28+, H06.05+, J06.03+)

• Deleting the mirror volume also deletes the mirror backup, if it exists.
• Always note the location of the disk that you delete. Once you delete a disk from the system
configuration database, it becomes unavailable to SCF. However:
◦ Installing an unconfigured disk in a slot generates an error message either at that time
or when the system is restarted.
◦ You can use OSM or TSM to view disks that are physically currently installed in system
slots. For more information, see the OSM or TSM online help for more information.
◦ For additional details, see “Displaying Information About Installed, Nonconfigured Internal
Disks” (page 48).
◦ Issue a START command to restart the IOP after deleting the mirror volume.
Example
1. Stop any new disk activity:
-> STOPOPENS $DATA14
2. Stop the disk:
-> STOP $DATA14
If any files on the disk are currently open, they are identified in the return message.
3. Delete $DATA14 from the system configuration database:
-> DELETE $DATA14
4. Confirm that the disk has been deleted:
-> INFO $DATA14
Write Caching
The WRITECACHE disk attribute controls whether write caching is performed for disk writes.
If write caching is disabled, when a disk write operation completes, disk status is returned only
after data is written to the drive media. If you enable write caching, data is written to the drive’s
cache and completion status is returned immediately (before the data is written to the drive media).
This allows for faster writes to SAS disks.
To enable write cache, set the WRITECACHE disk attribute to ENABLED. The default is DISABLED.
After changing the write cache setting, use the STATUS DISK command to determine the setting
that is in effect on the drive.
Considerations for WRITECACHE
• This attribute is available only on J06.03 and subsequent J-series RVUs.
• This attribute only affects CLIM-connected SAS disk drives. It is ignored for all other disks.
• The SUBSYS attribute UPS should be ON either before WRITECACHE is enabled or before
the IOP is started. Otherwise, the IOP will run with WRITECACHE disabled.
• If you set WRITECACHE to ENABLED for SAS HDDs or SSDs, you must have an HP rack mount
UPS to protect data during power interruptions.
• When adding a new disk on disk partitions, the writecache setting of the new disk must match
the writecache setting of the existing disk partitions.
94 Configuring Disks