scsimgr SCSI Management and Diagnostics utility on HP-UX 11i v3 (March 2008)

Main features and benefits
The main features and benefits of the scsimgr command include:
• Basic management and diagnostic capabilities for all SCSI objects (LUNs, lunpaths, target
paths and SCSI HBA controllers) independently of the drivers managing them.
• Plug-ins to handle operations dependent on device class (block, tape, changers, and so forth.)
or SCSI transport type (Fibre Channel (FC), Serial attached SCSI (SAS), parallel SCSI (pSCSI),
and so forth). When first released HP-UX 11i v3 provided three plug-ins respectively for:
block devices, tapes and auto-changers. These plug-ins allow scsimgr to display and set
status information, statistics and attributes specific to these classes of SCSI devices.
• Extended sets of statistics, status information, and attributes to aid in monitoring the operation
of the mass storage subsystem, and to simplify its management and troubleshooting.
• A flexible tunable architecture. Tunables can be set at different levels: global, a set of devices
meeting some criteria, and a SCSI object instance. This hierarchical tunable architecture is
very powerful. It allows the system administrator to fine tune the behavior of the stack to
optimally interoperate with devices with different operational requirements, to adjust the level
of resources used by the SCSI stack, and to work around some interoperability problems
discovered in the field without having to wait until a patch is rolled out.
• Support for online troubleshooting and maintenance operations to increase the system
availability. This includes:
- The ability to get a minimum set of information on devices in situations where normal
applications cannot open the device due to error conditions. The scsimgr command
uses a dedicated management device file to retrieve cached information without having
to open the device. In some cases it uses the pass-through driver to get information from
devices.
- Explicit validation of device replacement to prevent data corruption. The SCSI stack
implements mechanisms to authenticate devices based on the LUN Worldwide Identifier
(WWID). When a LUN with a different WWID is discovered through a previously
discovered lunpath, the system prevents I/O transfer to the device through that lunpath
until the system administrator validates the replacement.
- The capability to disable I/O transfers on a lunpath to a block device or on all lunpaths
to a block device, while performing online troubleshooting or maintenance operations.
For instance a maintenance operation can be carried out on the SAN, without having to
unmount file systems using affected disks, by simply disabling affected lunpaths.
• Contextual help providing information based on the command options specified.
• Capability to address SCSI objects using different types of identifiers including: class and
instance numbers, device files, and hardware paths.
4