IBM Tape Library Magstar 3494, Руководство оператора

Страница: 78 / 378

Physical Mount Required
The host requested a specific volser or specified a category that was not
designated as a “Fast-Ready” category. The volser needed to satisfy that
the mount operation is not resident in the tape volume cache and must be
recalled from the physical tape. The library manager directs the cartridge
accessor to move the required physical volume to one of the 3590 tape
drives managed by the VTS so the recall operation can be performed.
Demount Operations
The 3494 performs a physical demount operation whenever a volume is unloaded
from a physical tape drive. A similar operation occurs for the virtual tape drives
within a Virtual Tape Server. When a virtual volume is unloaded from a virtual tape
drive, a logical demount operation is performed.
The following are two types of demount operations:
v
A demount has been requested and the volume is currently at the tape drive.
For a physical demount, this operation is used to move a volume from a tape
drive to a storage cell. When the volume is placed in the storage cell, the
demount is considered complete.
For a logical demount, this operation updates the status of the virtual volume in
the library manager database to indicate that it is no longer mounted. No physical
movement of a volume is involved.
v
A demount has been requested and the volume has not yet been mounted.
This operation is used to cancel a mount operation that has not been started.
The library recognizes that since a demount request has been received for a
mount that has not yet taken place, the host must not really want the mount to
take place. Therefore, the demount request and the mount request cancel each
other.
Eject Operations
An eject operation results in a physical cartridge being placed in a cell of an output
facility in the library. The type of output facility may be either the Convenience
Input⁄Output Station or the High-Capacity output facility and is specified by the host
as part of the eject request. An eject request is considered complete when the
specified cartridge is placed in the cell of an output station. On completion, the
specified volume is removed from the library manager inventory.
Logical volumes managed by a Virtual Tape Server cannot be ejected from the
library unless they are assigned to the Insert category or a category designated as
a “Fast-Ready” category. Any host request to eject a logical volume not in the Insert
category or a “Fast-Ready” category will fail. An ejected logical volume is removed
from the library manager inventory.
Audit Operations
The purpose of an audit is to ensure (by using the vision system) that the physical
cartridge associated with the volser specified in the request is physically in the
library where expected. If the volser specified in the request is a physical volume
that is in the library manager’s inventory, the audit operation checks the external
label of the cartridge in the storage cell specified in the library manager database. It
must match what is in the database. If the volume is mounted on a tape drive, the
audit is held until the volume is demounted and returned to its storage cell.
56
Magstar 3494 Tape Library Operator Guide