Administrator's Guide

Managing Storage Volumes in Automated Libraries

ADSM tracks the scratch and private volumes available in an automated library through a library volume inventory. ADSM maintains an inventory for each automated library. The library volume inventory is separate from the inventory of volumes for each storage pool. To add a volume to a library's volume inventory, you check in a volume to that ADSM library. For details on the check-in procedure, see "Informing the Server about New Volumes in a Library".

To ensure that ADSM's library volume inventory remains accurate, you must check out volumes when you need to physically remove volumes from a SCSI or 3494 library device. When you check out a volume that is being used by a storage pool, the volume remains in the storage pool. If ADSM requires the volume to be mounted while it is checked out, a message to the mount operator's console is displayed with a request to check in the volume. If the check in is not successful, ADSM marks the volume as unavailable.

While a volume is in the library volume inventory, you can change its status from scratch to private, or from private to scratch.

To check whether ADSM's library volume inventory is consistent with the volumes that are physically in the library, you can audit the library. The inventory can become inaccurate if volumes are moved in and out of the library without informing the server via volume check-in or check-out.

See the following sections:

Tasks:
"Changing the Status of a Volume in a Library"
"Removing Volumes from a Library"
"Returning Volumes to a Library"
"Auditing a Library's Volume Inventory"

Changing the Status of a Volume in a Library

The UPDATE LIBVOLUME command lets you change the status of a volume in an automated library from scratch to private, or private to scratch. However, you cannot change the status of a volume from private to scratch if the volume belongs to a storage pool.

You can use this command if you make a mistake when checking in volumes to the library and assign the volumes the wrong status.

Removing Volumes from a Library

You may wish to remove a volume from an automated library. The following are examples:

• You have exported data to a volume in the library and want to take it to another system for an import operation.

• All of the volumes in the library are full, and you want to remove some that are not likely to be accessed in order to make room for new volumes that can be used to store more data.

To remove a volume from an automated library, use the CHECKOUT LIBVOLUME command. By default, the server mounts the volume being checked out and verifies the internal label. When the label is verified, the server removes the volume from the library volume inventory, and then moves it to the entry/exit port of the library. If the library does not have an entry/exit port, ADSM requests that the mount operator remove the volume from a slot within the library.

If you check out a volume that is defined in a storage pool, the server may attempt to access it later to read or write data. If this happens, the server requests that the volume be checked in.

Returning Volumes to a Library

When you check out a volume that is defined to a storage pool, to make the volume available again, you must do the following:

1. Check in the volume for the library, with private status. Use the CHECKIN LIBVOLUME command with the parameter STATUS=PRIVATE.
2. Update the volume's ACCESS value. You must change the access from unavailable to read/write or read-only. Use the UPDATE VOLUME command with the ACCESS parameter.

Managing a Full Library

As ADSM fills volumes in a storage pool, the number of volumes needed for the pool may exceed the physical capacity of the automated library. To make room for new volumes while keeping track of existing volumes, you can define an overflow location near the library for the storage pool. You then move media to the overflow location as needed.

The following shows a typical sequence of steps to manage a full library:

1. Define or update the storage pool associated with the automated library, including the overflow location parameter. For example, you have a storage pool named archivepool associated with an automated library. Update the storage pool to add an overflow location of Room2948. Enter this command:

   update stgpool archivepool ovflocation=Room2948
   

2. When the library becomes full, use the MOVE MEDIA command.

   ADSM records the location of the volumes that you move by using the MOVE MEDIA command. The location of the volumes is the overflow location that you defined for the storage pool. For example, to move all full volumes in the specified storage pool out of the library, enter this command:

   move media * stgpool=archivepool
   

   All full volumes are checked out of the library. ADSM records the location of the volumes as Room2948.

3. Check in new scratch volumes, if needed.

4. As requested through ADSM mount messages, check in volumes that ADSM needs for operations. The mount messages include the overflow location of the volumes.

To find the location of volumes in a storage pool that has an overflow location, you can use the QUERY MEDIA command. This command can also be used to generate commands. For example, you can issue a QUERY MEDIA command to get a list of all volumes in the overflow location, and at the same time generate the commands to check in all those volumes to the library. For example, enter this command:

query media format=cmd stgpool=archivepool whereovflocation=Room2948
cmd="checkin libvol autolib &vol status=private"
cmdfilename="/adsm/move/media/checkin.vols" 

The file that contains the generated commands can be run using the ADSM MACRO command. For this example, the file may look like this:

checkin libvol autolib TAPE13 status=private
checkin libvol autolib TAPE19 status=private

Auditing a Library's Volume Inventory

You can audit an automated library to ensure that ADSM's library volume inventory is consistent with the volumes that physically reside in the library. You may want to do this if the server's library volume inventory is disturbed due to manual intervention or movement of volumes within the library, or to problems with the server database. Use the AUDIT LIBRARY command to restore the inventory to a consistent state. Missing volumes are deleted and the locations of the moved volumes are updated; however, new volumes are not added during an audit. Unless your library has a bar-code reader, the server mounts each volume during the audit process to verify the internal labels on volumes.

Note:

Audit library processing waits until all volumes have been dismounted from drives within the specified library. If one or more volumes are mounted, but are in the IDLE state, you can force the volumes to be dismounted by issuing the DISMOUNT VOLUME command. Otherwise, the audit operation remains in a wait state until the idle volumes have been dismounted (the idle volumes are dismounted after the MOUNTRETENTION period expires).

Using a Library's Bar-Code Reader

To save time when auditing a library that has a bar-code reader, you can specify that the audit process use the bar-code reader to verify the identity of volumes. If a volume has a bar-code label, ADSM uses the characters on the label as the name for the volume during the audit. The volume is not mounted to verify that the external bar-code name matches the internal, recorded volume name.

If a volume has no bar-code label, ADSM mounts the volume in a drive and attempts to read the recorded label.

For example, to audit the TAPELIB library using its bar-code reader, enter the following command:

audit library tapelib checklabel=barcode

Maintaining a Supply of Scratch Volumes in an Automated Library

When you define a storage pool that is associated with an automated library (through the device class), you must specify a maximum number of scratch volumes equal to the physical capacity of the library. When the number of scratch volumes that ADSM is using for the storage pool exceeds that number, do the following:

1. Add scratch volumes to the library by checking in volumes. Label them if necessary.

   You may need to use an overflow location to move volumes out of the library to make room for these scratch volumes. See "Maintaining a Supply of Scratch Volumes".

2. Increase the maximum number of scratch volumes by updating the storage pool definition. The increase should equal the number of scratch volumes that you checked in.