volstat(8) System Manager's Manual volstat(8)
NAME
volstat - Logical Storage Manager statistics management utility
SYNOPSIS
/usr/sbin/volstat [-g diskgroup] [-i interval] [-c count] [-f format] [-r] [-psvd] [object...]
OPTIONS
The following options are recognized: Selects records from the specified disk group. The diskgroup option argument can be either a disk
group name or disk group ID. If no disk group is specified, only information from the rootdg disk group is displayed. Prints the change in
volume statistics that occurs after every interval seconds. The first interval is assumed to encompass the entire previous history of
objects. Subsequent displays will show statistics with a zero value if there has been no change since the previous interval. Stops after
printing interval statistics count times. Specifies the output format for the collected statistics. The default is -f s. The following
formats are available: Displays statistics on read and write operations. The output is formatted into six fields: the number of read opera-
tions, the number of write operations, the number of blocks read, the number of blocks written, the average time spent on read operations
in the interval, and the average time spent on write operations in the interval. These statistics are displayed as the default output for-
mat. Displays statistics on atomic copies performed (has meaning only for mirrored volumes) using the following fields: number of opera-
tions, number of blocks, and the average time spent per operation. Displays statistics on verified reads and writes (has meaning only for
mirrored volumes) using the following fields: number of verified read operations, number of verified write operations, number of blocks
read, number of blocks written, average time spent on verified read operations in the interval, and average time spent on verified write
operations in the interval. Displays the number of corrected (fixed) read and write operations (has meaning only for mirrored or RAID5
volumes).
Note
Currently, only read operations are corrected, so the number of fixed writes will always be zero. Displays the number of failed
read and write operations. Displays the statistics on read-writeback mirror consistency recovery operations (has meaning only for
mirrored volumes) using the following fields: number of read-writeback operations, number of blocks involved in read-writeback oper-
ations, and average time for completing a read-writeback operation. While in recovery mode, most read operations to a mirrored vol-
ume invoke read-writeback consistency recovery. Displays statistics for full-stripe writes on a RAID5 volume. The number of opera-
tions represents the number of write operations within a stripe that were conducted as a full-stripe write optimization. Full-stripe
writes represent considerably less overhead than read-modify-writes in terms of overall I/O time, latency and CPU overhead. The
total number of blocks represents the total size of the written data and the average time is the time taken for a full-stripe write
operation. Since the I/O may be larger than a single stripe, more than one stripe operation may be seen for a single logical I/O
request. Displays read-modify-write statistics. Each operation represents a read-modify write operation performed within a stripe.
I/O crossing a stripe boundary is represented by more than a single read-modify write operation. The number of blocks counted rep-
resents only the size of the requested write. The read portion of the I/O can be derived. Displays reconstruct write statistics.
Each operation counted is for a reconstruct write operation performed as an optimization of a write operation within a stripe. The
number of blocks counted represents the count of data blocks written not including parity or read operations. Displays reconstruct
read operations. Each operation is a separate reconstruct read operation. A single stripe read or write operation can lead to
numerous reconstruct read operations since each reconstruction takes place at the subdisk level. A detached column can consist of
several subdisks, each leading to a reconstruct read operation. Displays statistics for the VOL_R5_ZERO operation. Each operation
represents one call to the VOL_R5_ZERO ioctl. The number of blocks is based on the number of zero'd blocks written to the array.
The average time is the time taken to complete the entire ioctl operation. Displays statistics for the VOL_R5_RESYNC operation.
Each operation count represents one call to the VOL_R5_RESYNC ioctl. The number of blocks represents the resulting number of blocks
that were written to the parity regions as part of the resynchronization of parity. The read operations are not counted towards the
total. Displays statistics for the VOL_R5_RECOVER operation. Each operation count represents one call to the VOL_R5_RECOVER ioctl.
The number of blocks represents the resulting number of blocks that were written to the missing column region as part of the data
recovery. The read operations are not counted towards the total. Displays statistics for the VOL_R5_VERIFY operation. Each opera-
tion count represents one call to the VOL_R5_VERIFY ioctl. The number of blocks represents the resulting number of blocks that were
read as part of the RAID5 stripes consistency verification. Resets statistics instead of printing them. This option follows the
same selection rules as printing for any type selection arguments or for any named objects. If an interval was specified on the
command line, the first set of statistics will not be printed since they will have been reset to zero. Subsequent activity will
cause printing of statistics as normal. Displays statistics for volumes on the objects specified on the command line. For an
object that is a plex or a subdisk, displays information about the volume with which the object is associated. If an object sup-
plied is a disk, any volumes that occupy any part of the disk are selected. Displays statistics for plexes on the object specified
on the command line. For subdisk objects, displays information about a plex with which it is associated. Displays statistics for
subdisks on the objects specified on the command line. Displays statistics for disks on which the object specified on the command
line is fully or partially located.
DESCRIPTION
The volstat utility prints and resets statistics information on one or more volumes, plexes, subdisks, or disks.
The volstat utility reads statistics from the /dev/volinfo device to report performance statistics for volume, plex, subdisk, and disk
media objects. The statistics are since the last reboot, the last time they were reset, or for the interval specified.
The object parameter can be the name of a volume, plex, subdisk, or disk. If no object operands are given, statistics from all volumes in
the specified disk group are reported. If no disk group is specified, the rootdg disk group is implied.
Note
For TruCluster environments, the volstat command only reports statistic information for that node. It does not provide aggregate statistic
information for the whole TruCluster environment.
OUTPUT FORMAT
Summary statistics for each object are printed in one-line output records, preceded by two header lines. The output line consists of blank-
separated fields for the object type, object name (standard), and the fields requested by the -f switch in the order they are specified on
the command line.
If the -i interval option was supplied, statistics are prefaced with a time-stamp showing the current local time on the system.
For example, here is a sample of the output for a typical volstat session using the default format:
# volstat -vpsd -g data_g01 -i 10 -c 3
OPERATIONS BLOCKS AVG TIME(ms) TYP NAME READ WRITE READ WRITE READ
WRITE
Aug 22 12:25:23 1997 dm dsk135 119 210 2944 3392 18.9 2.8 dm dsk125 118 212
2928 3424 23.3 22.0 vol vol01 237 212 5872 3424 21.1 22.0 pl pl-01 118 212
2928 3424 23.3 22.0 sd dsk125-01 118 212 2928 3424 23.3 22.0 pl pl-02 119 210
2944 3392 18.9 2.8 sd dsk135-01 119 210 2944 3392 18.9 2.8
EXIT CODES
The volstat utility exits with a nonzero status if the attempted operation fails. A nonzero exit code is not a complete indicator of the
problems encountered, but rather denotes the first condition that prevented further execution of the utility. See volintro(8) for a list
of standard exit codes.
EXAMPLES
To display statistics for LSM volumes in the rootdg disk group, enter:
# volstat -v To display statistics for LSM volumes in a disk group called dg1, enter:
# volstat -g dg1 -v To display statistics for the plexes and subdisks of a volume named blop, enter:
# volstat -ps blop To reset all statistics for a disk group named foodg, enter:
# volstat -g foodg -r To display 5 sets of disk statistics at 10 second intervals, enter:
# volstat -i 10 -c 5 -d
SEE ALSO
volintro(8), voltrace(8)
volstat(8)