Installation guide

StorageWorks Secure Path for Windows NT
1-2 123995-002 EK-WNTMP-MH. D01
1.2 Secure Path Technology
Key to Secure Path’s functionality is the capability of dual StorageWorks RAID
controllers to operate in an active/active implementation referred to as dual-redundant
multiple-bus mode. Multiple-bus mode allows each controller to be configured on its own
bus and to process I/O independently under normal operation. Available storage units are
preferred to one or the other of the two controllers by setting a PREFERRED_PATH unit
attribute. This attribute determines which controller path is used for access at system boot
time. During runtime, units may be moved between paths at any time through use of the
Secure Path Management utility.
The Secure Path software detects the failure of I/O operations on a failed controller’s path
and automatically re-routes all traffic to the path of the surviving controller. Controller
and path failover is completed seamlessly, without process disruption or data loss.
Secure Path version 2.2 provides auto-failback capability. With auto-failback enabled,
Secure Path will monitor a failed path and automatically return failed-over storage units
to their original path, once the path has been restored. Anti-thrash filters are implemented
to prevent ping-pong effects resulting from marginal or intermittent conditions. The user
may select auto or manual failback policy through use of the Secure Path Management
utility.
Following a warm-swap of a failed controller, adapter or cable component, storage units
can be failed-back to their original path using the Secure Path Management utility.
To protect against drive failure in a Secure Path environment, storage units can be
configured using raid levels 0+1, 1, 3/5, or 5. Secure Path will support either FAT or
NTFS file system formats on single host configurations. Microsoft requires the NTFS file
system in Microsoft Cluster Server (MSCS) configurations.
1.3 Implementation
Secure Path’s primary failover capability is implemented in a Windows NT filter driver
called RaiDisk. RaiDisk provides support for the StorageWorks RAID subsystem
multiple-bus mode of operation and provides all functions required for monitoring I/O and
detecting path failures.