Dynamic Multi-Pathing 7.3.1 Administrator's Guide - Linux

Examples of using the vxdmpadm iostat command

Dynamic Multi-Pathing (DMP) enables you to gather and display I/O statistics with the vxdmpadm iostat command. This section provides an example session using the vxdmpadm iostat command.

The first command enables the gathering of I/O statistics:

# vxdmpadm iostat start

The next command displays the current statistics including the accumulated total numbers of read and write operations, and the kilobytes read and written, on all paths.

# vxdmpadm -u k iostat show all
                     cpu usage = 7952us    per cpu memory = 8192b
             OPERATIONS           BYTES         AVG TIME(ms)
PATHNAME READS     WRITES    READS     WRITES   READS   WRITES
sdf         87          0    44544k         0    0.00     0.00
sdk          0          0        0          0    0.00     0.00
sdg         87          0    44544k         0    0.00     0.00
sdl          0          0        0          0    0.00     0.00
sdh         87          0    44544k         0    0.00     0.00
sdm          0          0        0          0    0.00     0.00
sdi         87          0    44544k         0    0.00     0.00
sdn          0          0        0          0    0.00     0.00
sdj         87          0    44544k         0    0.00     0.00
sdo          0          0        0          0    0.00     0.00
sdj         87          0    44544k         0    0.00     0.00
sdp          0          0        0          0    0.00     0.00

The following command changes the amount of memory that vxdmpadm can use to accumulate the statistics:

# vxdmpadm iostat start memory=4096

The displayed statistics can be filtered by path name, DMP node name, and enclosure name (note that the per-CPU memory has changed following the previous command):

# vxdmpadm -u k iostat show pathname=sdk
                     cpu usage = 8132us    per cpu memory = 4096b
               OPERATIONS             BYTES             AVG TIME(ms)
PATHNAME    READS     WRITES      READS     WRITES     READS   WRITES
sdk             0          0          0          0      0.00     0.00

# vxdmpadm -u k iostat show dmpnodename=sdf
                     cpu usage = 8501us    per cpu memory = 4096b
               OPERATIONS             BYTES             AVG TIME(ms)
PATHNAME    READS     WRITES      READS     WRITES     READS   WRITES
sdf          1088          0    557056k          0      0.00     0.00

# vxdmpadm -u k iostat show enclosure=Disk
                    cpu usage = 8626us    per cpu memory = 4096b
               OPERATIONS             BYTES             AVG TIME(ms)
PATHNAME    READS     WRITES      READS     WRITES     READS   WRITES
sdf          1088          0    557056k          0      0.00     0.00

You can also specify the number of times to display the statistics and the time interval. Here the incremental statistics for a path are displayed twice with a 2-second interval:

# vxdmpadm iostat show pathname=sdk interval=2 count=2
                    cpu usage = 9621us    per cpu memory = 266240b
               OPERATIONS            BLOCKS          AVG TIME(ms)
PATHNAME    READS    WRITES     READS    WRITES     READS    WRITES
sdk         0         0         0         0          0.00      0.00

sdk         0         0         0         0          0.00      0.00