Preparing the host – HP StoreEver MSL6480 Tape Library User Manual
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that is not using an advanced path failover driver, the drive or library will reject the command with
an additional sense code of 82h/93h, FAILOVER SESSION SEQUENCE ERROR. That error code
should only be reported to an application if the advanced path failover drivers are not installed
on that host.
In a mixed environment where some hosts have advanced path failover drivers installed and some
hosts do not, the library should be partitioned so that one partition is accessed by hosts that are
using advanced path failover and the second partition is accessed by hosts that are not using
advanced path failover. In some cases a mix of host operating systems might be used with a single
partition. For example a Windows host might be running the library control agent and another
operating system is performing backups. In that configuration advanced control path failover could
be enabled and the advanced path failover driver installed on the library control host but the drives
may be configured without path failover.
If a single ESL G3 library needs to serve both hosts that have advanced path failover drivers
installed and hosts without advanced path failover drivers, the ESL G3 library can be configured
with pools of drives where all of the hosts with advanced path failover drivers use one pool of
drives and advanced data path failover is enabled on those drives. At the same time, a second
pool of drives in the same partition either has basic data path failover enabled or no data path
failover enabled. The second pool of drives is accessed by the hosts that do not have advanced
path failover drivers. The MSL6480 does not support mixing basic and advanced path failover,
so the drives connected to hosts without advanced path failover drivers must be configured without
path failover enabled.
For instructions on installing advanced path failover for your library, see:
•
ESL G3:
“Configuring failover for the HP StoreEver ESL G3 Tape Libraries” (page 20)
•
MSL6480:
“Configuring failover for HP StoreEver MSL6840 Tape Libraries” (page 27)
Preparing the host
Hosts used with advanced path failover must be configured with two different data paths and
should be configured with two different HBAs. For supported HBAs see the EBS compatibility matrix
on the HP Enterprise Backup Solutions (EBS) website:
For the highest level of fault protection, connect two different HBAs in the host to two different
SANs. This configuration provides full fault tolerance from both an HBA failure and a SAN switch
failure. If a single HBA is used, an HBA failure might result in loss of connection.
The advanced path failover drivers for Windows or Linux will select the first path that it discovers.
If you want the driver to select a particular SAN path, configure the host so that the HBA for your
preferred path is installed in the position with the lowest numbered bus location. Refer to your
server documentation for bus location information. The HP-UX operating system has built-in load
balancing and when a tape drive is opened the operating system will select the best path based
on the current path loading.
The Linux advanced path failover driver has a command for requesting a partition path to be
preferred. That setting will only persist until the next reboot because the hardware configuration
can change when the server reboots. The driver is unable to detect whether the hardware is the
same as the previous boot so the preferred setting is not retained across reboots. You can use a
boot time script to set the preferred path at each boot when the hardware configuration is stable.
After the host has been configured and booted, install the drivers necessary for the host operating
system.
•
“Installing and using Windows advanced path failover drivers” (page 35)
•
“Installing and using Linux advanced path failover drivers” (page 43)
•
“Installing and using HP-UX advanced path failover drivers” (page 47)
Preparing the host
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