An introduction to NDMP commands for Troubleshooting Backups or when checking Status of the NetApp filer.
NDMP, or Network Data Management Protocol, is a protocol invented by Network Appliance and PDC Software (acquired by Legato Systems, Inc., and now part of EMC.), meant to transport data between network attached storage (NAS) devices and backup devices.
How does NDMP control a tape library/Drive:
NDMP has a SCSI interface that allows an NDMP client to pass SCSI CDBs (command data blocks) through to the SCSI tape library attached to the NDMP server. NDMP allows an NDMP client to perform tasks such as positioning the tape and reading and writing tape labels.
Useful commands that can be used when troubleshooting a tape drive or library connected to a NetApp filer:
Show attached media changer:
sysconfig -m
Show attached tape drives:
sysconfig -t
Show attached RAID devices:
sysconfig -r
ndmpd variables:
on - Enables NDMP request-handling by the daemon. Enabling/disabling NDMP persists
across reboots.
off - Disables NDMP request-handling by the daemon. Processing continues for requests
that are already in progress. New requests are rejected. By default, NDMP service is
disabled at system startup.
status - Displays the current state of NDMP service.
probe [ session ] - Displays diagnostic information about the specified session. If session
is not specified, information about all sessions is displayed.
kill session - Signals the specified session to stop processing its current requests and
move to an inactive state. This allows hung sessions to be cleared without the need for a
reboot, since the off command waits until all sessions are inactive before turning off the
NDMP service.
killall - Signals all active sessions to stop processing their current requests and move to
an inactive state.
version [ maxversion ] - Displays the maximum version that NDMP currently supports when invoked without the optional maxversion. Sets the maximum version that NDMP allows when maxver_sion is specified. Currently supported values of maxversion are 2,3, and 4. By default, the maximum version is set to 4 at system startup. If maxversion is changed with ndmpd version maxversion, the changed value persists across reboots.
sysstat
sysstat <-c count> <-s> <-u|-x>
The sysstat command reports aggregated filer performance statistics, such as the current CPU utilization, the amount of network I/O, the amount of disk I/O, and the amount of tape I/O. When invoked with no arguments, the sysstat command prints a new line of statistics every 15 seconds. Use Ctrl-C or set the interval count (-c count) to stop the sysstat command.
Options:
-c count
Terminate the output after count number of iterations. The count is a positive, non-zero integer; values larger than LONG_MAX will be truncated to LONG_MAX.
-s
Displays a summary of the output columns upon termination, descriptive columns such as CP ty will not have summaries printed. Note that, with the exception of Cache hit, the Avg summary for percentage values is an average of percentages, not a true mean of the underlying data. The Avg is only intended as a gross indicator of performance. For more detailed information, use tools such as na_nfsstat, na_netstat, or statit.
-u
Displays the extended utilization statistics instead of the default display.
-x
Displays the extended output format instead of the default display. This includes all available output fields. Be aware that this produces output that is longer than 80 columns and is generally intended for off-line types of analysis and not for real-time viewing.
interval
A positive, non-zero integer that represents the reporting interval in seconds. If not provided, the default is 15 seconds.
More information can be found at www.ndmp.org
