Each shared drive has a host that is identified as the scan host. A scan host is the
host from which the automatic volume recognition process (avrd) scans unassigned
drives. (The robotic daemons scan assigned drives.) A scan host must have data
path access to the drive.
The EMM database contains the shared drive information; that information
includes the scan host. Media servers receive drive status information from the
EMM server.
EMM determines scan hosts; a scan host may be different
for each shared drive. The first host in the environment to
come online with a non-zero scan ability factor is the initial
scan host for its drives.
To configure the scan ability factor of media servers, use
the nbemmcmd command. For more information, see
NetBackup Commands Reference Guide.)
How the scan host is
determined
A scan host is assigned for a shared drive until some
interruption occurs.
For example, if one of the following occurs, EMM chooses
a new scan host:
■ The socket connection, the host, the drive, the drive path,
or the network goes down.
■ The drive is logically placed in the Down mode.
The scan host temporarily changes to hosts that request
tape mounts while the mount is in progress. Scan host
changes occur so only one host at a time has access to the
drive path.
The scan host can change
If a drive has multiple paths that are configured on the
selected scan host, EMM selects a scan path as follows:
■ The first local device path it finds in its database in the
UP state.
■ The first NDMP-attached drive path it finds in its
database in the UP state.
Drive paths for the scan host
Introducing the Shared Storage Option
About Shared Storage Option components
140
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