User's Guide

10 SCSI Command Support
Autocleaning
The library supports a user-configurable option to have the library automatically clean drives when
requested by the drives (refer to the specific library documentation for details). This process involves the
library loading a special cleaning cartridge into the requesting drive, allowing the drive to perform the
cleaning operation, and then the library unloading the cartridge and returning it to storage.
If this option is enabled and configured, the library maintains a pool of storage slots that contain the cleaning
cartridges. These slots and cartridges are not associated with or counted towards any logical library, and
as such are not reported to any application.
The library typically checks for cleaning requests from drives after unloading data cartridges. If a cleaning
request is found, the library will select a cleaning cartridge from the pool and perform the clean. While the
cleaning operation is in progress, the logical library containing the drive being cleaned will continue to
accept and perform SCSI commands. If a Move Medium command is received with the drive as a
destination, and it is still being cleaned, the command will be queued until the cleaning operation completes.
Cleaning operations vary by drive and conditions, but can take up to a few minutes to complete.
Element status for the Data Transfer element being cleaned will not reflect the presence of the cleaning
cartridge. It will continue to report that it is empty and accessible.
Removed Drives
Depending on how the library is configured, occasionally Data Transfer elements will be reported where no
drive is physically present at the time. This could be due to a drive that has been removed for service, or
simply a placeholder for the addition of a future drive. These empty “drive bays” will be counted and reported
via Mode Sense and Read Element Status commands. Status for such elements will indicate that they are
not accessible, and will report an ASC/ASCQ of 83/04. These elements could appear in between Data
Transfer elements that are present, creating “gaps” among the physical drives. This should not be
considered an error. Thus, removed drives will be reported in READ ELEMENT STATUS data with an
ACCESS bit set to zero and an EXCEPT bit set to one with a vendor specific ASC/ASCQ of 83/04h, DATA
TRANSFER ELEMENT NOT INSTALLED, or ASC/ASCQ 3B/1Ah, DATA TRANSFER DEVICE REMOVED.