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glmtrace - Group Lock Manager (GLM) trace utility


glmtrace [ -d ]

glmtrace [ -t locktype ] [ -f fset ] [ -v volid ] [ -i inumber ] [ filename ]




The glmtrace command prints lines that describe GLM trace events. Currently, the trace events are messages sent or received by a GLM master, on behalf of the given file. Only messages to or from a master on the current node are displayed. If the location of the master is unknown, run glmtrace on each node in the cluster.

Currently, glmtrace prints trace records indefinitely. To stop the printing, send glmtrace a signal, such as by typing Ctrl-C.

Trace records are written to a circular buffer in the kernel before being read and displayed by glmtrace. If this buffer becomes full, new entries are not added until glmtrace reads the oldest entries, which makes more room. The output contains the line "[lost records...]" at the appropriate point.

When glmtrace is invoked, the command clears the current trace buffer, and then waits for new trace records. Therefore, all events reported by glmtrace had occurred after glmtrace was invoked.

Since GLM uses a global trace buffer, you cannot run glmtrace more than once on the same node at the same time, even if the multiple invocations are naming different files.


The glmtrace command is intended primarily for troubleshooting by Veritas personnel. The command’s functionality and output are subject to change.


-t locktype Limit events to this locktype only. Locktype is rw (rwlock), h (hlock), g (glock), or pg (pglock). If you do not specify -t, glmtrace traces all locks for this file.
-f fset Limit events to files in this fileset. The argument is the fileset number. The default value of fset is 999.
-v volid Limit events to files on this volume. The volid argument is the number used by Cluster Volume Manager to identify the volume. If omitted, all files with the given inumber and fset are traced.
-i inumber Limit events to files with this inumber. This option may be omitted if a filename is supplied.
-d Disable tracing. This will cause any running glmtrace on the same node to terminate.
Currrently, GLM is unable to determine the fset and volid for the filename on the command line. These must be supplied explicitly if the defaults are unsuitable.

The arguments must include either a filename or an inumber (with -i). Currently, you cannot trace locks that are not associated with an inode, such as a cbuf lock. You also cannot trace locks for multiple files.

There is no option for enabling tracing; this happens when glmtrace is run. Once tracing is enabled, collecting the trace data imposes a small performance overhead. Tracing may be disabled explicitly with the -d option. Once no trace data has been read for 10 minutes, GLM disables tracing automatically.


Each line of output describes a message. The columns are:
time A timestamp telling when the message was sent or received. The units are seconds; the 3 digits after the decimal point are milliseconds. The timestamp may be usefully compared with other timestamps from the same node only.
msg The name of the message.
from The sending node of the message. These are the LLT node numbers, from /etc/llthosts.
to The receiving node of the message.
type The locktype. See the -t option.
reqid The request ID. This is an internal GLM number used for matching requests and responses.
flags Flags from the message. Values of interest are as follows:
00000002 GLM_GREEDY
00000004 GLM_SHPREF
00000008 GLM_ASYNC
00000020 GLM_TRY
00020000 GLM_GET_GRANT
10000000 GLM_STALE
20000000 GLM_GHOST
level The lock level requested.
range The range requested. This message is displayed for range locks only.
All numbers display in decimal, except the message flags, which display in hex.



VxFS 7.4 glmtrace(1m)