Week 1: Startup, Dispatcher, and Enqueue Services Unit 1 ... · Start and Stop process of SAP...

Week 1: Startup, Dispatcher, and Enqueue Services

Unit 1: Fundamentals of the SAP Start Service

2PUBLIC© 2017 SAP SE or an SAP affiliate company. All rights reserved. ǀ

Fundamentals of the SAP Start ServiceUsage (1)

The SAP start service is a key element of SAP

systems as of SAP NetWeaver 7.0.

The process is called sapstartsrv.exe on

Windows, and sapstartsrv on UNIX platforms.

This process is a service in Windows operating

systems; in UNIX operating systems, it is

scheduled as a daemon.

There is a separate sapstartsrv process for

each instance, which is responsible for starting,

stopping, and monitoring the instance.

SAP Host Agent also has its own SAP start

service.


Fundamentals of the SAP Start ServiceUsage (2)

The sapstartsrv program reads the instance

profile at the beginning. The profile defines

which steps must be performed during the start

process, and which processes of the instance

are started by sapstartsrv.

The profile defines that the database should be

started if it is not yet running.

Normally, the entries for the starting procedure

in instance profiles are not changed; if there

are any changes, sapstartsrv needs to be

restarted.


Fundamentals of the SAP Start ServiceFunctions

The SAP start service provides the following functions

for monitoring SAP systems, instances, and

processes:

Starting and stopping

Monitoring the runtime state

Reading logs, traces, profiles, configuration files

Technical information, such as network ports, active sessions,

thread lists, etc.

These services are provided on the SAPControl SOAP

Web service, and used by SAP monitoring tools like the

SAP Microsoft Management Console (SAP MMC) or SAP

Management Console (SAP MC).

You can get the list of all options and so-called Web

methods by running the ‘sapcontrol –h’ or ‘sapcontrol’

command.


Fundamentals of the SAP Start ServicePorts (1)

The start service binds to the following ports:

HTTP port 5<instancenumber>13 by default

(or sapctrl<instancenumber> in /etc/services)

HTTPS port 5<instancenumber>14 by default

(or sapctrls<instancenumber> in /etc/services)

Port information is included in sapstartsrv.log, in the work folder of every instance.


Fundamentals of the SAP Start ServicePorts (2)

If critical functions (“protected methods”, such as

restarting an instance) are not called using a

trusted connection, they require authentication

with an operating system user and password.

On UNIX platforms, trusted connections go through

UNIX domain sockets (/tmp/.sapstream<port-no>)

On Windows, they go through “Windows named pipe”

(\\<host>\pipe\sapcontrol_<instancenumber>)


Fundamentals of the SAP Start ServiceStartup process (1)

An SAP instance is started differently on

UNIX and Windows platforms:

UNIX

The startup procedure is initiated by the start

service, which ideally is started by the sapinit

script when the operating system is booted.

Afterwards, sapstartsrv triggers sapstart to

start the system.

The SAP start service definition is available

in the /usr/sap/sapservices file.



An SAP instance is started differently on

UNIX and Windows platforms:

Windows

On Windows, the start service is started

automatically when the operating system is

booted. The instance is started directly by

the start service.

The SAP start service definition is based on

Windows Registry entries.



The start service reads the instance profile and executes all commands in the instance profile that

contain an Execute_xx statement.

It then starts the processes of the SAP instance, respecting the sequential numbering of

Start_Program_xx statements.

Execute_xx and Start_Program_xx has its own, unique, sequential numbering, starting with 00.


Fundamentals of the SAP Start ServiceStart and Stop process of SAP NetWeaver AS ABAP (1)

Instances are started and stopped using

tools such as the SAP Management Console

(SAP MC), SAP Microsoft Management

Console (SAP MMC), or sapcontrol.

The tools for starting and stopping

communicate with the sapstartsrv process,

which also functions as a Web service.

The tools can be used to start or stop

individual instances or the entire system.


Fundamentals of the SAP Start ServiceStart and Stop process of SAP NetWeaver AS ABAP (2)

The sapstartsrv processes write a control file

to the $(DIR_GLOBAL)\sapcontrol directory

every minute. The name of the control file

indicates the port and host on which the

process can be accessed, and the priority of

its instance.

Using the control files, the sapstartsrv process

recognizes which other sapstartsrv processes

are still active, and starts the related instances

according to their priority.


Fundamentals of the SAP Start ServiceMonitoring tools

The following monitoring tools use the

Web service interface:

SAP Microsoft Management Console (SAP

MMC)

SAP Management Console (SAP MC)

sapcontrol: with sapcontrol (process name on

Windows sapcontrol.exe) you can call the

functions of the Web service interface from the

command field.


Fundamentals of the SAP Start ServiceSAP Microsoft Management Console (SAP MMC)

The SAP snap-in for the Microsoft

Management Console (MMC) provides a

graphical user interface to administer SAP

systems from Windows PCs.

By using SAP MMC you can start, stop, and

restart the instance, display the process list,

and display the ABAP work process table. A

lot of other functions are available as well for

all systems that appear in the tree.


Fundamentals of the SAP Start ServiceSAP Management Console (SAP MC) (1)

SAP Management Console (SAP MC) is an

operating-system-independent application.

This allows you to display various information

on monitoring and perform administration

tasks such as start and stop operations in the

same interface on different operating systems.

The tool is a standalone Java application,

which can be started either as an applet or

locally. The SAP MC is supplied as standard

with the kernel and is ready for use without

any additional installation. All you need is a

Web browser.


Fundamentals of the SAP Start ServiceSAP Management Console (SAP MC) (2)

To start the SAP MC after installing the

relevant SAP NetWeaver AS, enter the

following URL in your browser:

http://<host name>:5<instancenumber>13

https://<host name>:5<instancenumber>14


Fundamentals of the SAP Start ServiceSAPControl

SAPControl is part of the kernel, and is

available on all operating systems. Calling

sapcontrol, without any other options,

provides the syntax description.

SAPControl allows the Web services of the

sapstartsrv processes to be addressed.

Such methods are, for example: Start, Stop,

RestartInstance to operate, GetProcessList

to display the process list of an SAP

instance, StartService, StopService or

RestartService to operate the SAP start

service itself, and many more.

Contact information:

[email protected]

Thank you.

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Unit 2: Common SAP Startup Issues


Common SAP Startup IssuesHow to identify?

Identification:

SAP GUI: cannot log on to system, error is

partner ‘hostname:sapdp<nr>’ not reached

Management console: system is down or partially up

sapcontrol ... -function GetProcessList: displays

RED, GRAY or YELLOW processes


Common SAP Startup IssuesCategories

Startup issues – main categories:

SAP start service not running / cannot start

SAP instance cannot start


Common SAP Startup IssuesSAP start service (1)

SAP start service is normally started automatically at

operating system boot. Exactly one SAP start service

exists for every SAP instance. See also Unit 1.

Typical issues:

on Windows: service doesn't exist

sapstartsrv(.exe) doesn’t exist / corrupt / has zero size

sapstartsrv(.exe) and disp+work(.exe) release / patch is

different

profile doesn't exist / has incorrect entries

authorization issues

localhost name resolution is incorrect

on UNIX: socket or lock file doesn't exist / cannot be created

or accessed

on UNIX: sapservices file doesn’t exist / has incorrect entries



on Windows: service doesn't exist

When opening Windows service manager

(services.msc) the SAP start service

SAP<SID>_<instancenumber> doesn’t appear there.

In this case, you can reinstall it by right-clicking

$(DIR_EXECUTABLE)\sapstartsrv.exe > “Run as

administrator” and specifying:

SAP System ID (SID)

Instance number (NR)

Profile, the instance profile, with Start_Program_xx entries

User, which is <domain>\SAPService<SID>

Password of above user



sapstartsrv(.exe) doesn’t exist / corrupt / has zero size

Check if sapstartsrv(.exe) exists and its size:

on Windows: by file explorer

$(DIR_EXECUTABLE)\sapstartsrv.exe

on UNIX: by ‘ls -al $(DIR_EXECUTABLE)/sapstartsrv’

Validate sapstartsrv(.exe):

on Windows: by double-clicking it, a dialog window should appear

on UNIX: by calling ‘file $(DIR_EXECUTABLE)/sapstartsrv’ the

type ‘executable’ should appear in output; bit version (32 | 64)

and operating system should also match the host

If any of the above fails:

copy sapstartsrv from $(DIR_CT_RUN) to $(DIR_EXECUTABLE)

or extract it from corresponding SAPEXE.SAR or dw.sar archive



sapstartsrv(.exe) and disp+work(.exe) release /

patch is different

They must be on the same level, otherwise false

information may be delivered by sapstartsrv to startup or

monitoring tools.

To compare the versions:

on Windows: right-click

$(DIR_EXECUTABLE)\sapstartsrv.exe Properties

Details tab Product version

same for $(DIR_EXECUTABLE)\disp+work.exe

on UNIX:

‘strings $(DIR_EXECUTABLE)/sapstartsrv | grep SAPProduct’

same for $(DIR_EXECUTABLE)/disp+work

on both: by ‘sapcontrol ... -fuction GetVersionInfo’



profile doesn't exist / has incorrect entries

Check if profile exists:

on Windows: by file explorer

on UNIX: by “ls –al $(DIR_PROFILE)/<profile>”

Check the content:

with a text editor to see whether it is readable, no strange

entries allowed ($ _ : % = / # are valid characters)

whether SAPSYSTEMNAME (SID, e.g. TSL)

SAPSYSTEM (instancenumber, e.g. 00)

INSTANCE_NAME (instance, e.g. DVEBMGS00)

appear in the profile and match the instance of SAP

system



authorization issues

On Windows:

check if SAP_<SID>_*Admin groups have “Read&Execute”

rights on sapstartsrv.exe

<sid>adm and SAPService<SID> users are part of these

groups

On UNIX:

check if sapstartsrv is owned by <sid>adm with execute

rights



localhost name resolution is incorrect

sapcontrol connects to localhost by default to control or

monitor sapstartsrv or SAP instance. To check the name

resolution, run:

niping –v –H localhost

The above must resolve:

localhost to 127.0.0.1 or a valid local IP of the server, and vice-

versa

the full qualify hostname (localhost.<domain>) must be the same

Correct DNS or hosts file if necessary.

See also:

SAP Note 1476386 – Wrong localhost name resolution setting

SAP Note 1872990 – Various error messages related to incorrect

resolution of localhost

https://launchpad.support.sap.com/#/notes/1476386




on UNIX: socket or lock file doesn't exist /

cannot be created or accessed

When starting sapstartsrv, it needs to create...

/tmp/.sapstream5<instancenumber>13 (HTTP) socket

/tmp/.sapstream5<instancenumber>14 (HTTPS) socket

... or access

/tmp/.sapstartsrv<instancenumber>_sapstartsrv.log

lock file

Check if

they are owned by <sid>adm user

the access rights are correct (rwx for sockets, rw for

lock)

/tmp has the sticky-bit set (rwt)



on UNIX: sapservices doesn’t exist / has incorrect entries

Every local SAP start service is started automatically at

operating system boot as per the definition in

/usr/sap/sapservices.

sapcontrol also uses sapservices file to start or stop the SAP

start service of instances.

Check if:

file exists

can be read by <sid>adm (required for sapcontrol operations) and by

root (required for sapinit operations at boot)

library definition, sapstartsrv, and profile path are correct and exist

profile path must be /usr/sap/<SID>/SYS/profile/<instanceprofile>


Common SAP Startup IssuesTroubleshooting

Parameters / ways of troubleshooting

service/trace = 0 ... 3 in instance profile

default is 0, with this little information is written, only some headers,

list of ports, instance start and stop entries

It is worth setting it to 1 and restarting service to have more details in

$(DIR_HOME)\sapstartsrv.log

Windows: check Event Viewer Windows Logs System entries

regarding SAP start service

UNIX: start service online from command line (without -D option) to

display further information, i.e.

/<path>/sapstartsrv pf=/<path>/instanceprofile

sapcontrol ‘-debug’ option

sapcontrol -debug -prot <prot> -nr <instnr> -function <webmethod>

See also:

SAP Startup Troubleshooting Guide for NW Application Server

https://wiki.scn.sap.com/wiki/x/8IGuG


Common SAP Startup IssuesStart service running

At the end, check if:

SAP start service is running

sapcontrol calls are working (no error messages appear), e.g.:

sapcontrol -nr <instancenumber> -function GetProcessList

sapcontrol -nr <instancenumber> -function AccessCheck Start


Common SAP Startup IssuesSAP instance (1)

Startup tools

SAP Microsoft Management Console (SAP

MMC)

SAP Management Console (SAP MC)

sapcontrol

startsap script (available only for UNIX,

already deprecated)

See also Unit 1.



SAP instance cannot start

Typical issues:

sapcontrol authorization issues

an instance hasn’t started (yet) that others depend on

missing startup entries in profile / wrong profile used

port is in use



sapcontrol authorization issues

Typical error:

HTTP/1.1 401 Unauthorized

To reproduce:

sapcontrol -prot <prot> -nr <instnr> -function <webmethod>

sapcontrol -prot <prot> -nr <instnr> -function AccessChek

<webmethod>

The Web method is usually Start or Stop in such cases.

Check:

service/protectedwebmethods =

ALL|NONE|DEFAULT|SDEFAULT

It should be set to SDEFAULT (to its default value)

See also

927637 – Web service authentication in sapstartsrv as of

Release 7.00

https://launchpad.support.sap.com/



Correct startup sequence of SAP ABAP system

1. Database

2. Enqueue replication server (ERS) instance(s)

3. ABAP Central Services (ASCS) Instance, or if no ASCS

exists, the instance which includes message and enqueue

services: the classic central instance (CI)

4. Primary application server (PAS) instance and additional

application server (AAS) instance(s), or dialog instance(s)

(DI)



an instance hasn’t started (yet) that others depend on

The corresponding error is, for example:

in dev_disp

*** ERROR => DpTriggerMsAttach: Attach to Message Server

failed in dev_wXX trace

*** ERROR => EncNiConnect: unable to connect

(NIECONN_REFUSED)

Check the status of instances by:

sapcontrol –prot <protocol> -nr <instancenr>

GetSystemInstanceList

sapcontrol –prot <protocol> -host <host> -nr <instnr>

GetprocessList

The status of the instance that others depend on must be

‘GREEN’ before starting further instances; you can check

this with the above sapcontrol calls.



unavailability of startup entries in profile

Check which profile is in use:

on Windows: click Properties of

SAP<SID>_<instancenumber> service

on UNIX: outcome of ’ps –ef | grep sapstartsrv’ will

display /path/profile following pf=

Check startup entries:

open the above profile with text editor and check if

there are Start_Program_xx or Restart_Program_xx

entries available



port is in use

SAP system ports must be free to be able to start the

system. Ports are among others:

dispatcher port (32<instancenumber>)

gateway port (33<instancenumber>)

message server port (36<instancenr>) / internal port (39<instnr>)

ICM port (80<instancenumber>)

Error:

SI_EPORT_INUSE / NIESERV_USED

Use lsof or netstat to find what is blocking a port.

See also

TCP/IP Ports of All SAP Products

1845121 – Address already in use – how to find the process

listening on port ...

https://help.sap.com/viewer/575a9f0e56f34c6e8138439eefc32b16/2.0/en-US



Common SAP Startup IssuesTroubleshooting

Tips for troubleshooting

Check following:

newest developer traces in work folder of affected instance

entries of sapstart(srv).log or stderr<xx> in work folder

instance status by sapcontrol calls GetSystemInstanceList,

GetProcessList, AccessCheck <webmethod>

Parameters:

rdisp/TRACE = 0...3

Default value is 1

The higher the level, the more information will be written in

traces

See also:

SAP Startup Troubleshooting Guide for NetWeaver

Application Server

Standard error files of SAP workprocesses during

startup

Trace files of the startup processes – located in

/home/<SID>adm directory

Startup log of database, dispatcher and message

server

Standard trace files of the message server

Standard trace files of the dispatcher

Standard trace files of SAP workprocesses

https://wiki.scn.sap.com/wiki/x/8IGuG


[email protected]

Thank you.


Unit 3: Introduction to Dispatcher Queues


Introduction to Dispatcher QueuesOld concept prior to SAP NetWeaver 7.40

The dispatcher

has a queue for each work process type

Is responsible for the state of each work process

has to find a free work process for dispatching

Each work process has a local queue

for processing requests directly (without communication

via the dispatcher)

for processing asynchronous request (e.g., an aRFC

response)

The communication partner has to know whether a

session is attached to a work process or whether it

has to send the request via the dispatcher


Introduction to Dispatcher Queues New concept

A flexible request queue mechanism:

Queues can be created/destroyed dynamically

Multiple processes can listen to the same queue

A process can acquire a queue for exclusive use

Processes can attach/detach to the queue infrastructure dynamically

How do you use the new request queues?

Create one queue for each session

Work processes listen to different queues and take new requests

when they are free

Sessions can specify which kind of requests they can currently

process

Communication partners do not have to take care of whether a

session is active in a work process or not


Introduction to Dispatcher Queues Request queues overview

Processes have their own queue

Dispatcher / Gateway / ICM

Work process queues (each of which is handled by the

dedicated work process)

Session request queues

Each session has its own queue (handled by any free

work process of proper type)

Embryo queues: 1 for each worker type; sessions are

only created when requests are processed

Dispatch queues

When a session queue is not attached to a work

process, it is added to a “dispatch queue”.

There are 3, one for each session priority: high, medium,

low.


Introduction to Dispatcher Queues Monitoring of request queues (1)

Request queues of server processes

SM51: Goto Information Queue Information

Max. no of requests = 7 x rdisp/elem_per_queue

Local Work Processes


Introduction to Dispatcher Queues Monitoring of request queues (2)

Work process request queue

SM50: Process Information (CTRL-SHIFT-F11)

Process Information

Session request queues and session

request mask

SM04: User Technical Information


Introduction to Dispatcher Queues Request dispatching

Finding session queues for processing:

Each work process has to find the session queues that

need to be processed.

Request processing should be “fair”:

– Requests for sessions of the same kind are expected to

be handled in order of arrival.

– Requests for some sessions should have higher or lower

priority (GUI or batch processing).

Dispatch queues (queues of session queues):

Are observed by the work processes

There are three such queues for three priorities: high,

medium, low


Introduction to Dispatcher Queues Priorities as of 7.4x

High: request from UI (by default only SAP GUI)

Medium: all other requests (HTTP, RFC)

Low: batch processing (RFC started from BTC session)

Child processes have same or lower priority as their mother

process ABAP API to set RFC/HTTP session to high priority

(by default the priority is normal)

Runtime limit for dialog request:

rdisp/scheduler/prio_high/max_runtime Default: 10 min

rdisp/scheduler/prio_normal/max_runtime Default: 60 min

rdisp/scheduler/prio_low/max_runtime Default: no limit


Introduction to Dispatcher Queues Configuration changes

High load quota:

Protect the request queue from being flooded by requests for a certain worker type

Configuration via profile parameter rdisp/high_load_quota Default: load=90, queue=5

Task limit of sessions:

Protect the request queue from being flooded by requests for a single session

Configuration via profile parameter rdisp/task_limit Default: 1000

SAP Note: 2001276 – Changed configuration as of 7.40 SP2



[email protected]

Thank you.


Unit 4: Tools for Troubleshooting


Tools for TroubleshootingSnapshots

Snapshots can be triggered manually or are written by the

dispatcher when severe errors occurs in the instance like:

hard shutdown

exhausted resources

deadlock handling

icm/gateway crash

They are written in several steps:

The dispatcher writes all the accessible information to its trace file

All running work processes write information about what they are

currently executing (C stack)

A subsection of the trace files is written to the file system

Snapshots are packed as zip archives in the directory

$(DIR_GLOBAL)/sapcontrol/snapshots


Tools for TroubleshootingC stack (1)

Can be obtained:

Via transaction SM50

Externally via executable “sapstack”

sapstack <pid>

Unix: sapstack –tree <pid>

Windows: Sapstack Global\SAP<SID>_<NR>

SAP Note 1964673 – C-Call stack analysis

sapcontrol -nr <instance_number> -function

GetCallstack <pid>



Tools for TroubleshootingC stack (2)

SAP MMC, right-click a process:

Below the <signal

handler> we have

the running

functions


Tools for TroubleshootingSemaphore monitoring (1)

If a work process locks a particular resource,

it sets a semaphore.

Another work process that also wants to access

it must then wait.

In this case, the number of the semaphore is

displayed by SM50.

By pressing F1 in the Semaphore field, all the

SAP-related semaphores appear.

The wiki page What do the semaphores mean?

list all the semaphores dependent of the kernel

release.

https://wiki.scn.sap.com/wiki/x/wCtiGg


Tools for TroubleshootingSemaphore monitoring (2)

SAP Note 2027885 – External semaphore monitoring

semwatch pf=<profile>

Checks all possible SAP semaphores on all the instances

in one host.

Creates C stack of processes holding a semaphore longer

than 1s.

Can execute any user-defined command.

Can kill processes after a maximum semaphore hold time.

Independent of SAP release (since release 6.10)



Tools for TroubleshootingSAPControl

The WebSevices executed via SAPControl to monitor

the system should be restricted with the SAP profile

parameter “service/protectedwebmethods”.

sapcontrol -nr <nr> -function GetProcessList

sapcontrol -nr 00 -function ABAPGetWPTable

sapcontrol -nr 00 -function GetQueueStatistic [-repeat -1 1]

See Week 1 – Unit 1


Tools for Troubleshooting/sdf/mon (1)

Collect snapshots of monitoring transactions and

store this information for later analysis

Via transaction

/sdf/mon Schedule New Monitoring


Tools for Troubleshooting/sdf/mon (2)


[email protected]

Thank you.


Unit 5: Introduction to the Enqueue Service


Introduction to the Enqueue ServerEnqueue functionality (1)

Locking of application objects (DB entries) against

concurrent access:

The application cannot react to DB locks but could get

blocked

The Enqueue server allows locking on application

level, independent from the database locks to keep

data consistency

The knowledge about the enqueue locks must be

within a single instance: the “enqueue server”


Introduction to the Enqueue ServerEnqueue functionality (2)

SAP logical unit of work (LUW)

Dialog part of transaction update part

DB transaction DB transaction DB transaction

DIA-Wp 1 DIA-Wp 2 DIA-Wp 3

COMMIT

WORK

DB transaction

Update

Update-Wp


Introduction to the Enqueue ServerEnqueue parts

Parts of the enqueue logic

Lock argument

Lock owners (dialog & update)

Backup flag

Cumulation counter

Pure informational parts

Client

User name

Date, time, work process number, host

name (encoded in enqueue owner)

Transaction code

Lock object name


Introduction to the Enqueue ServerWhy standalone enqueue?

High availability requirements of customers

cannot be fulfilled with old enqueue architecture

Enqueue table in main memory

lost in case of a crash

single point of failure (SPOF)

Demands

– eliminate all SPOFs

– based on standard technologies

– as few changes to enqueue library as possible

Idea: create in memory replica on backup host

– in memory: due to performance requirements


Introduction to the Enqueue ServerCommunication architecture

Standalone

Enqueue

Server

Replication

Server

Replication

TableEnqueue Table

Enqueue

Client

Enqueue

ClientEnqueue

Client

Enqueue

Client Enqueue

Client

TCP/IP


Introduction to the Enqueue ServerThe Enqueue table

To check the location of the

enqueue server

Area of (shared) memory that holds the enqueues; three

sub-tables:

Owner tables

Argument tables

Lock table

Table size defined by parameter enque/table_size


Introduction to the Enqueue ServerEnqueue processing

Worker Thread

Replication

Thread

I/O-Thread

I/O-Thread

Enqueue

Library Enqueue

Table

Listen-Thread

Accept new

connections

Repl.

functionality

Replication

server

TCP/IPResponse Store

in shared

Memory

Enqueue

request

Enqueue

response

Rep.

request

Rep.

response

Enqueue

response

Thread

control

Enqueue

client


Introduction to the Enqueue ServerConfiguration

Enqueue Client

enque/process_location = REMOTESA

enque/serverhost = <hostname of enque server>

enque/serverinst = <instance number>

enque/encni/port = default: sapdp$(enque/serverinst)

enque/con_retries * enque/con_timeout:

Enqueue Server

enque/server/max_clients

enque/server/threadcount = <number of I/O threads>

enque/server/replication = [true|false]

enque/encni/repl_port

enque/table_size


Introduction to the Enqueue ServerGood to know

Lock object (SE11) Lock/Unlock function

modules

Form routine in function group SENA

SAPLSENA

Displaying trace files:

SAP Microsoft Management Console: Windows

SAP Management Console

File ENQHISOVR (work directory) gives

information about the top usages when an

overflow of the enqueue table occurs

SAP Note 746138 – Analyzing lock table

overflows



[email protected]

Thank you.


Unit 6: Enqueue Performance


Enqueue PerformanceAspects of enqueue performance

Enqueue calls consist of a communication part and a processing part

Identify if the problem is a communication problem or a processing problem

Do you have performance problems on both sides or only in the DI side?

Both sides: enqueue processing issue

Only on DI: communication issue

Enqueue

Server

Dialog

Instance

Communication channel

standalone enqueue server: TCP/IP


Enqueue PerformanceGeneral recommendations

The standalone enqueue server (ENSA) and database

shouldn't be placed in the same host sharing CPU

resources.

The number of I/O threads used in the enqueue server

(parameter enque/server/threadcount) should be 4.

A backup file is not needed when running standalone

enqueue with replication server.

Memory shortages can cause dramatic performance

decrease and replication interruption.

SAP Note 920979 – Out of memory in the standalone

enqueue server.



Enqueue PerformanceSymptoms (1)

STAD

Check enqueue time and count in STAD

In this example, we see 13 enqueue calls with a total time of 81ms 6.2ms per call



SM12

Check for big number of enqueue collisions

Check for operations that are very costly (read/backup) if

they occur very often (compared to the other operations)

Check that Wait time is smaller than Time in Lock Server



SM50/SM66

SAPLSENA running for long time in several

work processes

Possible reasons:

Disconnection with the enqueue server

Enqueue handling by the application


On the client side (dev_w*, dev_disp) On the server side (dev_enq*)

Enqueue PerformanceTools: Developer trace files


Enqueue PerformanceTools: Enqueue logging

Which locks were set and how long were they

retained?

In which order were the lock operations issued?

What is the result of an operation? Was it

successful?

Were there any lock conflicts and, if so, which

lock and users were concerned?

How many operations were carried out? What is

the current throughput?

How fast are locks transferred to the ERS?

Which enqueue client carried out a particular

operation?

SAP Note 2126913 – ENQU: The enqueue log



Enqueue PerformanceTools: Z_ENQUEUE_PERF

Functions:

Checks the configuration of the enqueue service

Performs a range of performance tests to assess possible

bottlenecks

Performs a range of tests to detect known problems

SAP Note 1320810 – Z_ENQUEUE_PERF

Via SM12; the program is called RSMONENQ_PERF



Enqueue PerformanceTools: enqt

Command Line Enqueue Test Tool

Can act as enqueue client and can attach to the

productive enqueue table for monitoring

can do almost everything like the SM12 test tools

used for long-term monitoring of the enqueue

performance (opcode 8)

could be started with a client profile or with the

enqueue server profile, depending on what you want


[email protected]

Thank you.

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