IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

216 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

write sequences: 2575

write seq. lengths: avg 273.6 min 256 max 512 sdev 64.8

seeks: 2575 (93.6%)

seek dist (blks): init 14252544,

avg 1725.9 min 256 max 511232 sdev 22428.8

seek dist (%tot blks):init 10.61897,

avg 0.00129 min 0.00019 max 0.38090 sdev 0.01671

time to next req(msec): avg 43.573 min 0.844 max 14016.443 sdev 365.314

throughput: 2922.4 KB/sec

utilization: 0.99

skipping to end.....................

In the filemon output, above, we notice:

򐂰 The most active logical volume is /dev/305glv (/interdiskfs); it is the busiest logical volume

with an average data rate of 87 MB/second.

򐂰 The Detailed Logical Volume Status shows an average write time of 1.816 ms for

/dev/305glv.

򐂰 The Detailed Physical Volume Stats shows an average write time of 1.934 ms for the

busiest disk, /dev/hdisk39, and 1.473 for /dev/hdisk55 for the next busiest disk.

The filemon command is a very useful tool to determine where a host is spending I/O. More

details on the filemon options and reports are available in the publication AIX 5L

Performance Tools Handbook, SG24-6039, which can be downloaded from:

http://publib-b.boulder.ibm.com/Redbooks.nsf/RedbookAbstracts/SG246039.html

7.4.4 lvmstat

A new performance monitoring tool was introduced in AIX 5L called lvmstat, which reports

input and output statistics for logical partitions, logical volumes, and volume groups. The

lvmstat command is useful in determining the I/O rates to LVM volume groups, logical

volumes and logical partitions. This is useful for dealing with unbalanced I/O situations where

data layout was not considered initially.

The lvmstat command generates reports that can be used to change the logical volume

configuration to better balance the input and output load between physical disks.

lvmstat resides in /usr/sbin and is part of the bos.rte.lvm file set, which is installed by default

from the AIX 5L base installation media.

The syntax of the lvmstat command is as follows:

lvmstat {-l |-v }Name [-e |-d ][-F ][-C ][-c Count ][-s ][ Interval [ Iterations ]]

Flags:

-c Count prints only the specified number of lines of statistics.

-C Causes the counters that keep track of the iocnt, Kb_read, and

Kb_wrtn to be cleared for the specified logical volume or volume

group.

-d Specifies that statistics collection should be disabled for the logical

volume or volume group specified.

-e Specifies that statistics collection should be enabled for the logical

volume or volume group specified.