Monitoring Linux resource usage

You should monitor system resource usage on any or all nodes in the cluster.

You should monitor system resource usage on any or all nodes in the cluster. You can use System Activity Reporting (SAR) to monitor resource usage.

Note

OpenText recommends that you install pstack and sysstat to help monitor Linux resources. The SYSSTAT package contains utilities for monitoring system performance and usage activity, such as sar, as well as tools you can schedule via cron to collect performance and activity data. See the SYSSTAT Web page for details.

The pstack utility lets you print a stack trace of a running process. See the PSTACK man page for details.

Run the top utility

$ top

A high CPU percentage in top indicates that Vertica is CPU-bound. For example:

top - 11:44:28 up 53 days, 23:47,  9 users,  load average: 0.91, 0.97, 0.81
Tasks: 123 total,   1 running, 122 sleeping,   0 stopped,   0 zombie
Cpu(s):  26.9%us,  1.3%sy,  0.0%ni, 71.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   4053136 total,  3882020k used,  171116 free,   407688 buffers
Swap:  4192956 total,   176k used,  4192780 free,  1526436 cached
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
13703 dbadmin    1   0 1374m 678m  55m S 99.9 17.1   6:21.70 vertica
 2606 root      16   0 32152  11m 2508 S  1.0  0.3   0:16.97 X
    1 root      16   0  4748  552  456 S  0.0  0.0   0:01.51 init
    2 root      RT  -5     0    0    0 S  0.0  0.0   0:04.92 migration/0
    3 root      34  19     0    0    0 S  0.0  0.0   0:11.75 ksoftirqd/0
...

Some possible reasons for high CPU usage are:

The Tuple Mover runs automatically and thus consumes CPU time even if there are no connections to the database.
The swappiness kernel parameter may not be set to 0. Execute the following command from the Linux command line to see the value of this parameter:
```
$ cat /proc/sys/vm/swappiness
```
If this value is not 0, change it by following the steps in Check for swappiness.
Some information sources:
- Red Hat
- Indiana University Unix Systems Support Group

Run the iostat utility. A high idle time in top at the same time as a high rate of blocks read in iostat indicates that Vertica is disk-bound. For example:

$ /usr/bin/iostat
Linux 2.6.18-164.el5 (qa01)     02/05/2011
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.77    2.32    0.76    0.68    0.00   95.47
Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
hda               0.37         3.40        10.37    2117723    6464640
sda               0.46         1.94        18.96    1208130   11816472
sdb               0.26         1.79        15.69    1114792    9781840
sdc               0.24         1.80        16.06    1119304   10010328
sdd               0.22         1.79        15.52    1117472    9676200
md0               8.37         7.31        66.23    4554834   41284840