Oracle Linux DBA Benefits

8/6/2019 Oracle Linux DBA Benefits

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watch Shows top server task details including server load average

ps Shows process-level details on resource consumption

These utilities are exceptional for monitoring Oracle databases and they can beplaced inside Linux shell scripts to take the output from the Linux commands and

store the information inside Oracle tables.

For example, here is a utility that will take the output from Linux vmstat utility and

insert the output into an Oracle table:

PATH=$ORACLE_HOME/bin:$PATH

export PATH

SERVER_NAME=`uname -a|awk '{print $2}'`

typeset -u SERVER_NAME

export SERVER_NAME

# sample every five minutes (300 seconds) . . . .

SAMPLE_TIME=300

while true

do

vmstat ${SAMPLE_TIME} 2 > /tmp/msg$$

# run vmstat and direct the output into the Oracle table . . .

cat /tmp/msg$$|sed 1,3d | awk '{ printf("%s %s %s %s %s %s\n", $1, $8, $9,

14, $15, $16) }' | while read RUNQUE PAGE_IN PAGE_OUT USER_CPU

SYSTEM_CPU


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IDLE_CPU

do

$ORACLE_HOME/bin/sqlplus -s perfstat/perfstat@testsys1


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We can use the same script technique with the Linux iostat utility and shell scripts

can be used to monitor disk I/O and place the details inside Oracle tables.

#!/bin/ksh

while true

do

iostat -x 300 1|\

sed 1,2d|\

awk '{ printf("%s %s %s\n", $1, $4, $5) }' |\

while read HDISK VMSTAT_IO_R VMSTAT_IO_W

do

if [ $VMSTAT_IO_R -gt 0 ] and [ $VMSTAT_IO_W -gt 0 ]

then

sqlplus -s perfstat/perfstat insert into

perfstat.stats\$iostat

values

(SYSDATE, 5, '$HDISK', $VMSTAT_IO_R,$VMSTAT_IO_W);

exit

!

fi

done

sleep 300

done


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As we see, the easy-to-use Linux monitoring utilities open-up a whole new world to

the Oracle DBA. If you take the time to master the Linux command syntax and

utilities you will gain the ability to diagnose any Oracle problem and always know

the exact cause of any OS-related performance issue. Now lets take a look at someof the command-line utilities for Linux and see how they can simplify the tasks of

the Oracle DBA.

Command Utilities for Linux

As we have noted, Linux has powerful command-line utilities that provideexceptional monitoring for every aspects of Oracles interactions with the hardware

environment. But there is more to Linux than the commands. The Oracle

professional will also need to master shell scripting, task scheduling and specialized

functions:

The vi file editor The vi editor is an extremely powerful text editor that is far more

powerful and flexible than Windows-based editors such as notepad.

Utility commands Linux provides powerful system tools such as grep, sed and awk

that allow you to create comprehensive OS monitoring facilities.

Job scheduling - The Linux crontab utility allows for scheduling OS tasks at specific

time intervals.

Scripting - Shell environments such as Korn shell, C shell, Bourne shell and Bourne

Again shell (bash) allow you to create sophisticated Linux monitoring scripts.

Linux tools are very powerful and flexible, and like any powerful tool, they are

complex. It can take years for the staff to master Linux internals, using the powerful

vi editor, and learning to program with UNIX shell scripts. Lets take a quick look at

the types of scripts that a Linux DBA might employ for their Oracle environment.


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There are many OS events that need to be monitored by the Oracle DBA and prior

to Oracle10g the DBA would want to be notified of any server-side event.

Operating System Events:

File system is filling rapidly

Server is paging RAM

High CPU enqueues

Messages in Linux syslog (I/O errors, bus errors)

Oracle OS events:

Alert log message

Core dump

Background dump

User dump created

For example, here is an example of an actual UNIX script for Oracle to detect a

almost-full filesystem:

#!/bin/ksh

for i in `df -k|grep /u0|awk '{ print $4 }'`

do

filesize=`expr i`

if [ $filesize -lt 100 ]

then


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configured, causing multiple buffer access whereby data blocks travel onto the UNIX

Journaled File System (JFS) buffer cache, and then transferred into the Oracle data

buffers.

This additional I/O overhead is a major problem and one that is automatic in Linux.Linux systems support direct I/O on a per-filehandle basis (which is much more

flexible), and Oracle enables this O_DIRECT feature automatically. This is not true

for those using Sun, HP and Veritas I/O, and tricky utilities must be implemented to

enable direct I/O:

Solaris Uses the "forcedirectio" option. Oracle DBAs claim this option makes a

huge difference in I/O speed for Sun servers.

AIX - Uses the "dio" option.

Veritas VxFS - (including HP-UX, Solaris and AIX), uses the "convosync=direct". It is

also possible to enable direct I/O on a per-file basis using Veritas QIO; refer to the

"qiostat" command and corresponding man page for hints.

In sum, using Linux with a hardware vendor such as UNISYS ensures that the Linux

environment is optimized to run as quickly as possible. Now lets look at the issue of

migrating to Linux from Windows and proprietary UNIX.

Migrating to Linux from Proprietary UNIX

Migrating into Linux can be very easy or very difficult, depending on your existing

Oracle configuration. It is not uncommon to see small dialect differences between

implementations of UNIX, especially with respect to display output and command

arguments.

Those shops that find a migration difficult are those that have made extensive use

of operating system utilities for their Oracle functions:


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External scheduling of Oracle tasks

Crontab

Windows at scheduling

Extensive use of OS shell scripts

Automated e-mail alerts (new dumps, alert log messages, Linux syslog

messages)

File system alerts

Server overload alerts

If you avoid the OS trap and use Oracle to schedule all Oracle tasks you can easily

port your database across OS platforms. This is especially true if you migrate to

Oracle10g where Oracle automatically collects OS metrics and has a built-in alert

and scheduling mechanism:

Migrate to Oracle10g

Schedule all Oracle tasks with dbms_scheduler

Use the Oracle dbms_alert package to replace OS scripting

Lets take a closer look at the syntax differences between proprietary UNIX and

Linux so that you can appreciate the challenge of migration.

Linux command syntax

Users of proprietary UNIX will immediately recognize many similarities between

Sun, HP, AIX and Linux commands. However, there are significant syntax issues,

especially with regard to command arguments and the output from Linux utilities:


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Linux Command Syntax examples

Display the number of CPUs cat /proc/cpuinfo|grep processor|wc l

Show top CPU% ps aux|sort -n +2

Display top-10 CPU consumers ps aux|sort -rn +2|head -10

RAM memory display free

Shutdown server as root /sbin/shutdown -r now

Kill all xxx processes pkill [-9] xxx

Show swap paging space /sbin/swapon -s

Show Linux syslog errors tail /var/log/messages

Show swap disk details swapon -s

See held memory segments ipcs -m

Show Linux system parms sysctl -a

Linux command history files history|more

Migrating from Sun to Linux can be especially problematic because of the syntax

differences and the different output from the utilities such as vmstat and netstat.

This can cause considerable re-writing of shell scripts.

vmstat Linux:

>vmstat 2 5

procs memory swap io system cpu

r b w swpd free buff cache si bi bo in cs us sy id

1 0 0 140 90372 726988 26228 0 0 0 14 7 0 0 4


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0 0 0 140 90372 726988 26228 0 0 2 103 11 0 0 100

vmstat Solaris:

>vmstat 2 5

procs memory page disk faults cpu

r b w swap free re mf pi po s6 -- -- in sy cs us sy id

0 0 0 2949744 988800 0 4 0 0 0 0 0 148 200 41 0 0 99

0 0 0 2874808 938960 27 247 0 1 0 0 0 196 434 64 1 2 98

Display number of CPUs:

Linux:

>cat /proc/cpuinfo|grep processor|wc -l

16

Solaris:

>psrinfo -v|grep "Status of processor"|wc -l

8

RAM Size in Linux:


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>free

total used free shared buffers cached

Mem: 3728668 504688 3223980 41316 430072 29440

-/+ buffers/cache: 45176 3683492

Swap: 265032 608 264424

RAM Size in Solaris:

>prtconf|grep -i mem

Memory size: 2048 Megabytes

memory (driver not attached)

virtual-memory (driver not attached)

Netstat Differences

On any Sun and Linux server the netstat utility provides information about all

network traffic touching the server. However the output from the

Solaris netstat

>netstat


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TCP: IPv4

Local Address Remote Address Swind Send-Q Rwind Recv-Q State

------------- ------------------- ----- ------ ----- ------ -----------

sting.32773 ting.1521 32768 0 32768 0 ESTABLISHED



Linux netstat

In Linux, we see that the output from netstat is quite different from Solaris:

>netstat

Proto Recv-Q Send-Q Local Address Foreign Address State

tcp 0 0 donsrv1.rov:netbios-ssn intranet.janet.com:1351 ESTABLISHED

tcp 0 0 donsrv1.janet.com:1120 sting.janet.com:ssh TIME_WAIT

tcp 0 40 donsrv1.janet.com:ssh h pop3-146.gloryroa:1096 ESTABLISHED

Ironically, the syntax differences between proprietary UNIX and Linux can hinder

your migration and shops that use SFU on Windows often have a far easier

migration. In sum, those Oracle shops that avoid OS utilities such as scheduling

(crontab) and shell scripts will find database migration very easy.

2. Linux commands for Oracle DBA


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Posted by Kamran Agayev A. on February 22, 2009

Today I would like to introduce you some articles related to advanced Linuxcommands. These commands will be useful when working with Oracle Database

Therere 5 articles that I would like to introduce you

Oracle Linux DBA Benefits

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