vxtrace(1M)

NAME

vxtrace — trace operations on volumes

SYNOPSIS

vxtrace [-aeEls ] [-b buffersize] [-c eventcount] [-d outputfile] [-f inputfile] [-g diskgroup] [-k buffersize] [-m millisec_delay] [-o objtype [,objtype]...] [-t timeout] [-w waitinterval] [name | device]...

DESCRIPTION

The vxtrace utility prints kernel error or I/O trace event records on the standard output or writes them to a file in binary format. Binary trace records written to a file can be read back and formatted by vxtrace as well.

If no arguments are specified, vxtrace reports either all error trace data or all I/O trace data on all virtual disk devices. With error trace data, it is possible to select all accumulated error trace data, to wait for new error trace data, or both (the default). Selection can be limited to a specific disk group, to specific Volume Manager kernel I/O object types, or to particular named objects or devices.

Under heavy loads, the kernel may discard one or more records before they can be reported to vxtrace. Even though the contents of the records are lost, the kernel keeps track of the number of lost records and reports this to vxtrace. as a record. vxtrace displays this record indicating that records were lost. You can increase the size of the kernel buffer using the -k buffersize option to reduce the likelihood of the kernel discarding records.

Note: Some Volume Manager usage messages, manual pages, and command output contain terms and descriptions related to the VERITAS Storage Replicator for Volume Manager (SRVM). SRVM is not supported in this release, so you should ignore options and fields that refer to RLINK, RVG, and DCM.

OPTIONS

-a

Appends to the outputfile instead of truncating it. By default, the output file is truncated.

-b buffersize

Sets the size of the buffer used by vxtrace when it obtains trace records from the kernel, or from a file when the -f option is specified. The buffer size is specified as a standard Volume Manager length (see vxintro(1M)). The default buffer size is 8K.

-c eventcount

Accumulates at most eventcount events and then exits. The timeout and eventcount options can be used together.

-d outputfile

Writes (dumps) binary trace data to the specified output file.

-e

Selects new error trace data. The default is to select I/O trace data.

-E

Selects pre-existing error trace data. This can be combined with -e to get both pre-existing trace data and new trace data.

-f inputfile

Reads binary trace data from the specified input file, instead of from the Volume Manager kernel.

-g diskgroup

Selects objects from the specified disk group. The disk group can be specified either by disk group ID or by disk group name. With no name or device arguments, all appropriate objects in the disk group are selected. With the name argument, diskgroup specifies the disk group that contains the named configuration record.

-k buffersize

Sets the kernel I/O trace buffer size. The Volume Manager kernel allocates a private kernel space to buffer the I/O trace records for each vxtrace command. The default buffer size is 8K bytes. Some trace records may be discarded if the trace buffer is too small. This option can be used to set a larger or a smaller kernel trace buffer size. The buffer size is specified as a standard Volume Manager length (see vxintro(1M)). Depending on the Volume Manager kernel configuration, usually only a maximum buffer size of 1 megabyte is granted.

-l

Long format. Prints all available fields for all tracing records, instead of a subset of the available fields. The default is to use the short format.

-m millisec_delay

Pauses vxtrace for the specified period to allow more records to accumulate.

name | device

If name or device are specified, Volume Manager kernel objects of the requested types are selected if they are associated with the configuration records or virtual disk devices indicated by those arguments.

-o objtype [,objtype]...

Selects object based on the objtype option arguments. Multiple types of objects can be specified with one or several -o options. The possible object selection types are:

all | ALL: Selects all possible virtual disk devices, kernel objects, and physical disks.
dev | logical: Selects virtual disk devices.
disk | physical: Selects VxVM physical disks.
log: Selects all log objects.
logplex: Selects RAID-5 log plexes.
logsd: Selects DRL (dirty region logging) or RAID-5 log subdisks.
logvol: Selects DRL or RAID-5 log volumes.
m | mv | mirror: Selects mirrored volume kernel objects.
p | pl | plex: Selects striped or concatenated plex kernel objects.
rl | rlink: Selects RLINK kernel objects. If an RVG (replicated volume group) is specified, all RLINKs associated with that RVG are selected.
s | sd | subdisk: Selects subdisk kernel objects.
v | vol | volume: Selects mirrored or RAID-5 volume kernel objects.

-s

Specifies using synchronous writes to the outputfile instead of asynchronous writes. Asynchronous writes is the default.

-t timeout

Accumulates trace data for at most timeout seconds, then exits.

-w waitinterval

If vxtrace waits for waitinterval seconds without receiving any new events, prints waiting... to allow scripts to wake up and process previously accumulated events. This is useful for processing errors. The waiting... message does not count as an event for the purposes of the -c option.

ARGUMENTS

Arguments specify configuration record names, or physical or virtual disk device nodes (by device path). If no object types were selected with the -o option, only trace records corresponding to the indicated configuration records or devices are selected; otherwise, objects of the requested types are selected if they are associated in any way with the named configuration record or device.

If a name argument does not match a regular configuration record, but does match a disk access record, the indicated physical disk is selected. Physical disks can also be selected by the disk media record name.

By default, name arguments are searched for in all disk groups or in the disk group specified using the -g option. Without the -g option, a record that is found in more than one disk group generates an error unless the record is in the rootdg disk group (in which case, the record in the rootdg disk group is selected). The disk group for any individual name argument can be overridden using the form:

diskgroup/recordname 

Note: When reading trace data from a file with the -f option, association information is not available.

EXAMPLES

To trace all physical disk I/Os, enter:

vxtrace -o disk 

To trace virtual disk device I/Os to the device associated with volume testvol, use either of the commands:

vxtrace -o dev testvol 
vxtrace /dev/vx/dsk/testvol 

To trace all log subdisks associated with volume testvol, enter:

vxtrace -o logsd testvol 

To trace all log objects, enter:

vxtrace -o log 

To accumulate ten seconds worth of trace data for disk04 and then format that data, use:

vxtrace -t 10 -d /tmp/tracedata disk04 
vxtrace -l -f /tmp/tracedata 

To read error trace data into a script for processing, using ten second pauses to generate mail messages, use the command:

vxtrace -leE -w 10 | while read ... 

FILES

/dev/vx/trace

vxtrace(1M)

Technical documentation

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