Troubleshooting Guide

Other Commands

This section describes some essential UNIX-based commands for troubleshooting and performance monitoring. For details on any one of these commands, precede it with man on the command line.

AIX Troubleshooting Commands

The following AIX system commands are useful for DB2 troubleshooting:

errpt

The errpt command reports system errors such as hardware errors and network failures.

For an overview that shows one line per error, use errpt
For a more detailed view that shows one page for each error, use errpt -a
For errors with an error number of "1581762B", use errpt -a -j 1581762B
To find out if you ran out of paging space in the past, use errpt | grep SYSVMM
To find out if there are token ring card or disk problems, check the errpt output for the phrases "disk" and "tr0"

lsps

The lsps -a command monitors and displays how paging space is being used.

lsattr

This command displays various operating system parameters. For example, use the following command to find out the amount of real memory on the node:

lsattr -l sys0 -E

This example lets you see the maximum number of processes per user.

xmperf

For AIX systems using Motif, this command starts a graphical monitor that collects and displays system-related performance data. The monitor displays 3-dimensional diagrams for each node in a single window, and is good for high-level monitoring. However, if activity is low, the output from this monitor is of limited value.

UNIX-Based Troubleshooting Commands

The following UNIX-based system commands are also useful for DB2 troubleshooting. These commands are for all UNIX-based systems, including AIX, unless otherwise noted.

df

The df command lets you see if file systems are full.

To see how much free space is in all file systems (including mounted ones), use df
To see how much free space is in all file systems with names containing "dev", use df | grep dev
To see how much free space is in your home file system, use df /home
To see how much free space is in the file system "tmp", use df /tmp
To see if there is enough free space on the machine, check the output from the following commands: df /usr, df /var, df /tmp, and df /home

truss

Available for SVR4 UNIX-based environments such as Solaris Operating Environment, Siemens-Nixdorf, SCO OpenServer, and Silicon Graphics IRIX, this command is useful for tracing system calls in one or more processes. It is not available for AIX.

SAM

Available for HP-UX, the System Administrative Management (SAM) tool provides information on hardware errors.

pstack

Available for Solaris 2.5.1 or later, the /usr/proc/bin/pstack command displays stack traceback information. The /usr/proc/bin directory contains other tools for debugging processes that appear to be suspended.

Performance Monitoring Tools

The following tools are available for monitoring the performance of your UNIX-based system. For a full description of the commands, see the AIX for RISC System/6000 Performance Monitoring and Tuning Guide, or the equivalent guide for the system you are using.

vmstat

This command is ideal for monitoring paging rate, which can be found under the page in (pi) and page out (po) columns. Other important columns are the amount of allocated virtual storage (avm) and free virtual storage (fre).

This command is useful for determining if something is suspended or just taking a long time.

iostat

This command is useful for monitoring I/O activities. You can use the read and write rate to estimate the amount of time required for certain SQL operations (if they are the only activity on the system).

This command is also useful for determining if something is suspended or just taking a long time.

netstat

This command lets you know the network traffic on each node, and the number of error packets encountered. It is useful for isolating network problems.

System file

Available for Solaris Operating Environment, the /etc/system file contains definitions for kernel configuration limits such as the maximum number of users allowed on the system at a time, the maximum number of processes per user, and the inter-process communication (IPC) limits on size and number of resources. These limits are important because they affect DB2 performance on a Solaris Operating Environment machine. Refer to the Quick Beginnings for further information.

Commands for DB2 Enterprise - Extended Edition

For DB2 Enterprise - Extended Edition systems with a db2nodes.cfg file, you can run UNIX-based commands on all DB2 nodes by surrounding the commands with quotation marks and preceding them with one of the following prefix commands:

db2_all

Provides information for all logical nodes. The following example shows active applications for all logical nodes:

db2_all ";db2 LIST APPLICATIONS"

rah

Provides information for all physical nodes. This command is useful for filtering out multiple entries that might occur using db2_all when there are multiple logical nodes on machines. The following example lists the first three lines of the hardware error log for each physical node:

rah ";errpt | head -3"

The semicolon (;) improves performance by issuing commands simultaneously to all nodes. For information on other syntax for db2_all and rah, see the file raw README in the misc subdirectory of the sqllib directory and the Administration Guide, Design and Implementation in the appendix on this subject.

The following commands are also useful for DB2 Enterprise - Extended Edition systems:

spmon

If using multiple nodes on RS/6000 SP systems, you may need to check if the high performance switch (HPS) is running on all workstations.

To view the status of all nodes, use one of the following commands from the control workstation:

spmon -d for ASCII output
spmon -g for a graphical user interface

Alternatively, use the command netstat -i from a node workstation to see if the switch is down. If the switch is down, there is an asterisk (*) beside the node name. For example:

css0* 65520 <Link>0.0.0.0.0.0

The asterisk does not appear if the switch is up.

db2_call_stack

The db2_call_stack diagnostic tool writes the call stack for each DB2 process to a trap file. See Trap Files, for more information.

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