user's guide for kernel tuning - baansupport.com iv c4 kernel tuning guide.pdf · hp-ux....

Infor Baan IVc

User's Guide for Kernel Tuning

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Publication Information

Document code: U7622B US

Release: Infor Baan IVc

Publication date: October 06

Table of Contents

Chapter 1 To tune the Operating System for Infor Baan IVc....................................................1-1 Parallel processing ......................................................................................................................1-2

Chapter 2 MS Windows configuration Settings.........................................................................2-1 Switches in file C:\boot.ini .......................................................................................................2-1 Optimize system for background services...............................................................................2-2 Configure Server service.........................................................................................................2-3 Winstation Heap Size..............................................................................................................2-3

Chapter 3 Unix Kernel Parameters .............................................................................................3-1 Processes ....................................................................................................................................3-2

NPROC...................................................................................................................................3-2 Files .............................................................................................................................................3-3

NFILE......................................................................................................................................3-4 NOFILES, SFNOLIM (SVR4), MAXFILES (HP), RLIM_FD_CUR (SUN), RLIM_FD_MAX(SUN) .............................................................................................................3-4

Buffers .........................................................................................................................................3-5 NBUF ......................................................................................................................................3-5 NBUF (SVR4) .........................................................................................................................3-6 NHBUF....................................................................................................................................3-6

Shared memory ...........................................................................................................................3-7 SHMALL..................................................................................................................................3-7 SHMMAX ................................................................................................................................3-8

ii | Table of Contents

SHMMIN .................................................................................................................................3-8 SHMMNI .................................................................................................................................3-9 SHMSEG ................................................................................................................................3-9

Semaphores ..............................................................................................................................3-10 SEMMAP ..............................................................................................................................3-10 SEMMNI................................................................................................................................3-10 SEMMNS ..............................................................................................................................3-11 SEMMNU..............................................................................................................................3-11 SEMUME ..............................................................................................................................3-11

Messages ..................................................................................................................................3-12 MSGMAP..............................................................................................................................3-12 MSGMAX..............................................................................................................................3-13 MSGMNB..............................................................................................................................3-13 MSGMNI ...............................................................................................................................3-13 MSGSEG ..............................................................................................................................3-14 MSGSSZ...............................................................................................................................3-14 MSGTQL...............................................................................................................................3-16

General kernel parameters ........................................................................................................3-16 MAXUSERS..........................................................................................................................3-16 MAXUPROC, MAX-PROC-PER-USER ................................................................................3-17 NPTY, NPTYS ......................................................................................................................3-17

Chapter 4 System Specific Tuning .............................................................................................xix Hewlett Packard – HP-UX............................................................................................................ xix

NBUF ...................................................................................................................................... xix BUFPAGES ............................................................................................................................ xix DBC_MIN_PCT and DBC_MAX_PCT ..................................................................................... xx

Hewlett Packard – Tru64 UNIX..................................................................................................... xx FIFO-DO-ADDAPTIVE............................................................................................................ xxi

iii | Table of Contents

UBC_MINPERCENT, UBC_MAXPERCENT, UBC_BORROWPERCENT and VM_UBCSEQSTARTPERCENT............................................................................................. xxi GH_FAIL_IF_NO_MEM ..........................................................................................................xxii INSECURE_BIND..................................................................................................................xxiii VM_SWAP_EAGER or /SBIN/SWAPDEFAULT ....................................................................xxiii /DEV/TIMEDEV......................................................................................................................xxiii

SUN / Fujitsu Siemens – Solaris .................................................................................................xxiv NBUF/NPROC .......................................................................................................................xxiv PT_CNT.................................................................................................................................xxiv PRIORITY_PAGING/ FASTSCAN/ MAXPGIO ......................................................................xxiv

iv | Table of Contents

About this Guide

Before you install Infor Baan IVc, check the OS kernel. If necessary, changes must be made to avoid problems during the installation if multiple users try to enter the system or at production. This document explains the kernel parameters that must be set on various platforms.

This guide contains the following four chapters:

Chapter 1, “To tune the OS Kernel for Infor Baan IVc,” describes the tasks you must make to adjust the underlying operating system for Infor Baan IVc.

Chapter 2, “MS Windows configuration settings,” describes the advised settings for the Windows 2000 and 2003 environment.

Chapter 3, “UNIX kernel parameters,” lists the involved kernel parameters for the UNIX platform.

Chapter 4, “System-specific tuning,” lists additional tuning data for specific platforms

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vi | About this Guide

This version of the Kernel Tuning Guide supplies the following information.

Explicit behavior of the specific settings.

Kernel settings for Parallel Processing.

MS Windows 2000 and MS Windows 2003 settings.

These settings are valid only for Infor Baan IVc. If you add other products, this can affect the system, in which case you must read the documentation of these products to find their particular kernel settings.

Database-specific settings are not added to this document. For information on the database-specific settings, refer to the official database documentation.

This document also describes the kernel and configuration parameters from several hardware platforms. The following platforms are specified in this document:

HP-UX.

Compaq Tru64 Unix.

Solaris for the SUN and the Fujitsu Siemens platform.

MS Windows 2000 and MS Windows 2003.

AS/400 and OS/390 are not included because AS/400 the kernel is self-tuning and specific tuning is not necessary for a Infor Baan IVc installation and OS/390 is to specific for this document

1Chapter 1 To tune the Operating System for Infor Baan IVc

1-2 | To tune the Operating System for Infor Baan IVc

Parallel processing

In some batch sessions, parallel processing can be used to speed up the performance. When this feature is enabled, the job is spread over multiple bshells. If a batch session is configured to run with parallel bshells, the main program starts up more bshells to spread the load. Running with multiple bshells makes only sense when more than one CPU(or CPU Cores/Threads) is available in the system. The communication protocol between the parallel bshells is based on message queues, which on MS Windows platforms is configured automatically, though in most cases it needs to be set on UNIX.

The following guidelines and values are for UNIX kernels.

To get parallel processing running, the message queues must be configured in the kernel with at least the following settings:

Description Minimum value

Maximum message length (bytes) 256

Messages per message queue 1024

Size per message queue (bytes) 1024 * 256 = 262144

Number of message queues system wide 2 * #parallel bshells + 6

Messages system wide 1024 * (2 * #parallel bshells + 6)

The settings are based on:

The maximum number of parallel bshells running on all parallel sessions

Only used for parallel processing. In situations where other products also make use of message queues, use the sum of the numbers.

If these settings have values that are below the default OS values, you must use the default OS values.

The MS Windows platform’s kernel is completely different compared to a UNIX kernel. To optimize performance, some important settings are required. This Chapter discusses the MS Windows 2000 and 2003 settings.

Switches in file C:\boot.ini

The following switches can be needed by Infor Baan IVc:

/PAE With this switch, the system can use more than 4GB of memory. MS Windows 2000: With Advanced Server, 8GB of memory can be used. With Datacenter, 32 GB of memory can be used. MS Windows 2003: With Advanced Server, 32GB of memory can be used. With Datacenter, 64 GB of memory can be used. This parameter is not needed anymore for MS Windows 2003 64-bit(x64)

/3GB With this switch, the user’s virtual memory address space can be enlarged from 2GB to 3GB. Enlarging user’s virtual memory space on MS Windows 2003 64-bit (x64) is not needed if using a 64-bits database

2Chapter 2 MS Windows configuration Settings

2-2 | MS Windows configuration Settings

Optimize system for background services

Description

If you use a system as server, you must spread the CPU load on all tasks. Foreground processes must not get special priority compared to background applications.

Setting

MS Windows 2000: Go to System Properties -> Advanced -> Performance Options -> Application Response -> Background services.

MS Windows 2003: Go to System Properties -> Advanced -> Performance -> Performance Options -> Advanced: - Process scheduling, Background services - Memory usage: Programs

MS Windows configuration Settings | 2-3

Configure Server service

Description

MS Windows 2000 and MS Windows 2003 can tune the server for the job it must do. Infor Baan IVc is an application that needs a server which memory is optimized for distributed applications that perform their own memory caching.

Setting

Go to Network and Dial-up Connections -> Local Area Connection -> File and Printer Sharing for Microsoft Networks Properties. Select Maximize throughput for network applications.

Winstation Heap Size

Description

MS Windows 2000 and 2003 maintain registry settings to control the heap size for desktops associated with non-interactive window stations. Some non Infor Baan IVc programs changes this value during installation. It is recommended to change this value only when you experience problems.

2-4 | MS Windows configuration Settings

Change the HEAP SIZE value directly in the registry, so be very careful. The registry key is in HKEY_LOCAL_MACHINE:

\System\CurrentControlSet\Control\Session Manager\SubSystems

with value-name Windows. The value-name consists of a list of values. The one of our interest is SharedSection=1024,3072. The SharedSection value can have 4 values. Normally the last two values are not specified and defaults are used.

Settings

When you experience problems with Infor Baan IVc you can try to increase or add the third value. But you must be careful. Increasing this value makes it possible that more processes can be started. You must try to increase this value into steps of 512, 1024, 2048, 3072 or 4096. An example:

SharedSection=1024,3072,2048

Tuning

The problem observed, when this value is to low, is:

Connection problems to Infor Baan IVc server or MS SQL Server

Popup messages on console from sort.exe with message “User32.dll or Kernel32.dll Fails to Initialize”

Note: It is known that this value conflicts with the use of Terminal Services. Therefore it is recommended not to use Terminal Services on the Infor Baan IVc server.

It is observed on some MS Windows 2003 servers running older hardware that setting this value too high (2048 or higher) the server will not boot any more. You need to fall back on the last known good configuration.

For MS Windows 2003 64-bit (x64) second and third value can set to high values without any danger for boot problems

This chapter describes the different generic UNIX kernel parameters. In general these parameters can be split up in the following categories:

Processes.

Files.

Buffers.

Shared memory.

Semaphores.

Messages.

General kernel parameters.

Hardware-specific kernel parameters.

Except for the hardware-specific kernel parameter category, all the other parameters will be discussed later in this chapter. The specific hardware parameters will be discussed in the next chapter.

The parameter name mentioned in the next sections is the common name. The parameter names can have slightly different names on each platform, but is must be recognizable.

3Chapter 3 Unix Kernel Parameters

3-2 | Unix Kernel Parameters

In the formulas a number of variables are used. Their definition is as follows:

#connected user: Max number of connected users on the system. Those users do not have to be active, but consume still system resources. It is assumed that each end user is logged on only once. Increase the number of connected users with the extra logons of each end user.

#additional database drivers: Extra database drivers needed to access multiple database instances concurrently. Each connected user uses normally one database instance and there for one database driver. In special situation this value is larger than zero.

Processes

These parameters are related to the number of processes that run on a Infor Baan IVc environment. Dependent on the configuration, connection method and some other variables these parameters must be set.

NPROC

Description

Specifies the maximum number of processes that can run simultaneously system-wide.

Value

Dependent on the configuration it must be set to the following value:

2-tier 3-tier application server

3-tier database server

NPROC 5 * #connected users + 512

* #connected users + 512

2 * #connected users + 512

These settings are based on:

Each connection contains a bshell, a database driver, an audit driver a database backend process and one additional process. In case of special circumstances, the number of processes must be increased.

Unix Kernel Parameters | 3-3

Each user connects to Infor Baan IVc via WebTop or the Worktop.

Each user runs one database driver. In case of multiple database drivers, the number of processes must be increased with:

2-tier 3-tier application server

3-tier database server

NPROC = NPROC +

2 * #additional database drivers * # connected users

#additional database drivers * # connected users

#additional database drivers * # connected users

The number of 512 of additional processes is based on a common

environment with a database. In case of additional products, the total amount of processes must be increased.

Connected users Tuning

The value of NPROC must be increased when UNIX error 11 occurs: No more processes.

The current and maximum number of processes can be found in the column proc -sz from the sar -v output.

Note: On some UNIX systems an extra command:

sh –c /.../ipc_boot6.2…

is started by the inetd. This can be prevented by giving the user a korn shell (/usr/bin/ksh) as login shell in /etc/passwd in stead of a born shell (/bin/sh).

Files

The file parameters contain all types of parameters that are related with files. Infor Baan IVc reads a great deal of files, but closes them almost directly after reading. Therefore, most of the values can be kept small.


NFILE

Description

The value of this parameter specifies the number of files that may be opened simultaneously system-wide.

Value

Infor Baan IVc only uses a couple of files at the same moment and the maximum number of open files at a certain moment that will be opened are:

NFILE >= 16* #connected users + 1024(with a minimum of 1024)

For OS tasks and database activities it is safe to add another 1024.

Tuning

The number of this parameter must be increased when error 23 appears File table overflow. The current and maximum number of open files can be found in the column file-sz from the sar -v output.

NOFILES, SFNOLIM (SVR4), MAXFILES (HP), RLIM_FD_CUR (SUN), RLIM_FD_MAX(SUN)

Description

Specifies the maximum number of files that can be opened per process.

Value

Contrary to the database, Infor Baan IVc does not use numerous files at a same time. A save value is:

NOFILES >= 256

Tuning

The number of this parameter must be increased when error 24 appears: Too many open files.


Buffers

The buffer parameters specify how much memory must be reserved for I/O buffering. For most Infor Baan IVc environments, the database activity and not the Infor Baan IVc processes generates almost all I/O.

NBUF

Description

Specifies the number of system buffers available for block I/O and data I/O.

Value

Infor Baan IVc does very little I/O. In general 5% of the internal memory is sufficient for system buffers. In case a database is also running on the system, take the amount of transferred I/O of that database also into account. In case of a database with raw devices 5% is still sufficient, otherwise in most cases the value of NBUF must be increased to 10% of the internal memory. The number of buffers must be set low because each database can reserve memory for database buffers. Normally it is better to allocate buffers in the database than to use that memory for UNIX buffer cache.

If the system has a high I/O to disk but has a lot of memory on disk than the NBUF must not be set to 10% of the internal memory but to a much smaller value, for example, 5%.

Tuning

If the system suffers due to less memory (paging or swapping), check if NBUF can be reduced.

If there is more than enough memory in the system, check if increasing NBUF makes sense. On several systems the I/O can be monitored with sar –b and sar –u.


NBUF (SVR4)

Description

In UNIX SVR4, buffers only contain inode, superblock(s) and file header information; they do not contain file data. The actual file data is stored in pages of virtual memory. The NBUF parameter specifies the number of system buffer headers available for block I/O.

Value

The value for NBUF can be set to the default value, for example, 100.

Tuning

On several systems the I/O can be monitored with sar –b and sar –u.

NHBUF

Description

Specifies the number of hash table entries that can be allocated in the system.

Value

The value of NHBUF is dependent of the value of NBUF. By default it can be set to:

NHBUF = 1/5 * NBUF

The value of NHBUF must be a power of 2.

Tuning

No advice for tuning yet.


Shared memory

Infor Baan IVc uses shared memory to share data definitions and objects. Data stored in the shared memory can be shared between users. It improves performance because a data definition or object that is stored in shared memory does not need to be read from disk anymore. It saves memory because now the object or data definition is only read once instead of multiple times in memory. The shared memory parameters are specified in the $BSE/lib/shm_param file. Values of SHM_BUFSIZE and SHM_MAXMEM are close related to the parameters SHMMAX and SHMMNI. You must make few shared memory segments for Infor Baan IVc. Setting SHMMAX to 16MB or higher is recommended.

Note:

For the latest portingsets (6.1c.07.13 and above ) $BSE/lib/shm_param is not used anymore. $BSE/lib/shm_config is used instead. In exceptional cases, if you may need to force an SHM attach address (all UNIX platforms, except HP PA-RISC and Itanium) or an SHM size, the file shm_config can be edited. It is possible to fall back to the old behavior (using shm_param) by setting the resource 'shm_compat_mode:1' in $BSE/lib/default/all file.

SHMALL

Description

Specifies the maximum number of shared memory text segments that can be created.

Value

SHMALL = SHMMNI

Tuning

Increase when error 24 occurs on a shared memory text segment.


SHMMAX

Description

Specifies the maximum size of a shared memory segment that can be created in bytes. Several shared memory segments of this size can be created in an environment (per process).

Value

The minimum value for SHMMAX = 4194304 (4 MB). You must set SHMMAX at least to 16MB:

SHMMAX = 16777216

In case a database also runs on the same system, you must take the recommended value from the database vendor. In most cases it will be between 60% till 100% of internal memory.

Tuning

Increase in case of error 22.

SHMMIN

Description

Specifies the minimum size of a shared memory segment in bytes.

Value

Specify this parameter to the smallest value to get all programs be able to create a shared memory segment:

SHMMIN = 1

Tuning

No recommendations.


SHMMNI

Description

Specifies the maximum number of shared memory identifiers that can be created system-wide.

Value

The value of SHMMNI must be dependent on the number of Infor Baan IVc environments, databases and other programs that use shared memory. In a single Infor Baan IVc, single database environment setting to 30 is sufficient.

Tuning

The number of shared memory segments can be monitored with ipcs –m. If the number of shared memory segments comes close to SHMMNI, you must increase the parameter to prevent problems later. Check all other resources that use shared memory to specify an optimal value. Increase when error 28 occurs.

SHMSEG

Description

Specifies the maximum number of shared memory segments that can be created by a process.

Value

The number of shared memory must be kept as small as possible. The following setting is sufficient for SHMSEG in most situations:

SHMSEG = 30

Tuning

In case of a bad tuned environment this parameter can run out of its value. In this case check the value of SHMMAX and Infor Baan IVc or database parameters before increasing this value. Increase when error 24 occurs.


Semaphores

Semaphores are used to protect programs, shared memory and message queues. In Infor Baan IVc, semaphores are used when something must be written in shared memory with Java integrations and with parallel processing.

SEMMAP

Description

Specifies the number of entries in the control map, used to manage semaphores. This map is used to keep track of free areas in the system pool of semaphores.

Value

Set the number of SEMMAP 2 higher than SEMMNI:

SEMMAP = SEMMNI + 2

Tuning

Increase when error mfree map overflow occurs.

SEMMNI

Description

Specifies the maximum number of semaphore identifiers in the kernel. This is the number of unique semaphore sets that can be active at any given time.

Value

In general, it is safe to set this value to 128.

Tuning

Increase when error 28 occurs.


SEMMNS

Description

Specifies the maximum number of semaphores permitted in the system.

Value

Keep SEMMNS to the same number as SEMMNI:

SEMMNS = SEMMNI

Tuning

The number of semaphores can be monitored with ipcs –sb

SEMMNU

Description

Specifies the number of undo structures in the system.

Value

Keep SEMMNU to the same number as SEMMNI:

SEMMNU = SEMMNI

Tuning


SEMUME

Description

Specifies the maximum number of undo entries per undo structure. Each undo entry represents a semaphore that has been modified with the undo flag specified in the semop(2) system call.


Value

Keep the default value for SEMUME, for example:

SEMUME = 10

Tuning


Messages

Messages can be used for communication between processes and/or parallel processing. In most cases, communication between processes by message queues is not the most optimal performing method and therefore can be skipped for configuring message queues in the kernel. If message queues (m) are used in the $BSE/lib/ipc_info it is advised to see if it can be changed into pipes (p).

MSGMAP

Description

Specifies the number of entries in the control map, used to manage message segments. Each entry in this map represents a free area in the message buffer area.

Value

The default value can be used for this parameter, for example:

MSGMAP = 100

Tuning

Increase when error mfree map overflow occurs.


MSGMAX

Description

Specifies the maximum size of a message in bytes.

Value

Because the messages from the parallel processing are relative small, a maximum size of 4096 is sufficient for Infor Baan IVc and most of the times also for other products. At least, MSGMAX must be lower than MSGMNB.

MSGMAX = 4096

Tuning

No tuning advise yet.

MSGMNB

Description

Specifies the maximum length (in bytes) of a message queue.

Value

The maximum number of bytes in a message queue is 262144, so MSGMNB must be set to at least this value:

MSGMNB >= 262144

Tuning

The number of bytes in a message queue can be checked with ipcs –qo.

MSGMNI

Description

Specifies the maximum number of message queues that can be used system-wide.


Value

The number of needed message queues for Infor Baan IVc is relative small. On most systems 64 message queues is sufficient. For more information on how to calculate the number of message queues, refer to Chapter 1 “To tune the OS kernel for Infor Baan IVc.”

MSGMNI = 64

Tuning


MSGSEG

Description

Specifies the number of message segments permitted on the system. Each message on a message queue consists of one or more message segments (the size of each segment is specified by the MSGSSZ parameter).

Value

This parameter can be set to the default value, for example:

MSGSEG = 1024

Tuning

No tuning advise yet.

MSGSSZ

Description

Specifies the size (in bytes) of a message segment. Each message consists of a contiguous set of message segments large enough to hold the text of the message.

Value

This parameter can be set to the default value, for example:

MSGSSZ = 8


Tuning

No tuning advice yet.


MSGTQL

Description

Specifies the maximum number of message headers, that is the maximum number of open messages.

Value

Keep this parameter equal to MSGMNI:

MSGTQL = MSGMNI

Tuning

No tuning advice yet.

General kernel parameters

MAXUSERS

Description

This parameter is used for a lot of kernel parameters to calculate default values. Parameters that are not explicitly specified can get a value through this internal formula.

Value

Set the value of MAXUSERS to the number of expected connected users at any time.

MAXUSERS = #connected users + 10

Tuning

Tune to the number of users after changing, for example, the number of licenses.


MAXUPROC, MAX-PROC-PER-USER

Description

This parameter describes the number of processes enabled to run under a certain user id.

Value

The value depends on the configuration. In most situations the default value is fine but there are some exceptions when this parameter must be increased, for example:

Multiple users run under the same userid. This occurs often before going live. Several users logon under the id of bsp and together they generate a lot of processes.

If BSE_REM is used some customers prefer to run all users as one particular remote user, for example, the user bsp. In that case the number of processes per user need to be increased.

On a three-tier database server, all processes run with the process ID of the database owner on several databases. As a result, you must increase the number of processes per user.

Above situations are some of the situations that can cause problems on this parameter. If any of these situations seem to occur, calculate the max number of needed processes per user and tune the parameter.

Tuning

If you run out on processes, increase, but lower if and when possible.

NPTY, NPTYS

Description

When users connect to the system(directly via BA or BX user interface) a pseudo terminal is used. The number of pseudo terminal is specified with the parameter NPTY.


Value

The value of NPTY must be set to the number of connected Baan users plus some additional for system maintenance.

NPTY = #licensed users + 10

Tuning

Increase before running out of connections.

This chapter describes the system specific tuning parameters per platform.

Hewlett Packard – HP-UX

NBUF

Value

This parameter must be set to 0 because it is obsolete.

BUFPAGES

Description

Specifies the number of pages in the file system buffer cache. The description and calculation of the non-HP NBUF parameter is applicable to this parameter.

Value

To set the field to Dynamic, and specify the following:

BUFPAGES = 0

If more control on this parameter is needed, a fixed value can be specified. If set to 0, the lower and upper boundary can be specified with the parameters DBC_MIN_PCT and DBC_MAX_PCT.

4Chapter 4 System Specific Tuning

4-20 | System Specific Tuning

Tuning

Depends on the usage of the system. If Infor Baan IVc is the only application on the system, it can be set to 0.

DBC_MIN_PCT and DBC_MAX_PCT

Description

Specifies the minimum and maximum percentage of memory used for buffer pages. If BUFPAGES is set to 0, these parameters will be taken for a lower and upper boundary for the buffer pages.

Value

The value for these parameters is dependent on the configuration. System usage is required to use these parameters. Therefore, you must watch the memory usage over a period of time and tune the parameters to the system behavior.

Hewlett Packard – Tru64 UNIX

Note: All described Tru64 UNIX kernel parameters are located in /etc/sysconfigtab.

You can no longer change one or more kernel parameters by editing the sysconfigtab file with an editor, but must either create a stanza file for these subsystem(s)/parameter(s) and enter these (new) values by means of sysconfigdb, or you can use a dxkerneltuner if you use an X-based station.

For more information about adding/changing kernel parameters, refer to the appropriate man pages of:

sysconfigtab. sysconfig. sysconfigdb. stanza. dxkerneltuner.

System Specific Tuning | 4-21

FIFO-DO-ADDAPTIVE

Description

In Tru64 pipes are optimized for the traditional UNIX piping mechanism. To change the IPC behavior from tuned for throughput (bandwidth) to low latency messaging the parameter fifo-do-adaptive has been introduced.

Value

It needs to be disabled (set to zero) for Infor Baan IVc:

vfs: fifo-do-adaptive = 0

UBC_MINPERCENT, UBC_MAXPERCENT, UBC_BORROWPERCENT and VM_UBCSEQSTARTPERCENT

Description

UBC_MINPERCENT and UBC_MAXPERCENT specifies the minimum and maximum percentage of memory used for buffer pages. UBC_BORROWPERCENT specifies the amount of memory above which memory is borrowed from the virtual memory subsystem. If NBUF is set to 0, these parameters will be taken for a lower and upper boundary for the buffer pages. UBC_BORROWPERCENT must be equal or larger than UBC_MINPERCENT and smaller or equal than UBC_MAXPERCENT.

Value

The values for these parameters are dependent on the configuration. On going performance analyzing will be necessary to find the correct values. For a typical environment, where the database is on top of (AdvFS) file systems, the values might look as follows.

vm: ubc_minpercent = 5 ubc_maxpercent = 10 ubc_borrowpercent = 8 vm_ubcseqstartpercent = 7

Starting with Tru64 UNIX V5.0A, however, AdvFS supports direct, asynchronous I/O. Starting with Oracle 8.1.7, the RDBMS will default in using this feature (open the database files with the O_DIRECTIO flag) when on top of AdvFS and running on Tru64 UNIX V5.0A or above. As a result, although AdvFS is used, I/Os will not be buffered in system buffer cache. This gives a new approach to tuning UBC when using this feature. Since these I/Os will not be buffered, the values can be increased to allow the use of more UBC for other purposes. The following are examples of typical values:


vm: ubc_minpercent = 10 ubc_maxpercent = 40 ubc_borrowpercent = 20 vm_ubcseqstartpercent = 15

Again, long-term measurement may be needed to find the correct settings for a particular configuration. Through a patch, previous versions of Oracle supports asynchronous direct I/O. Contact Oracle support for the appropriate Oracle versions and the availability of these patches.

GH_FAIL_IF_NO_MEM

Description

If enabled (1) specifies that an error is returned by the shmget function when granularity hints are in use and there is insufficient memory allocated through gh_chunks. Under certain conditions, this might result in a hang of the RDBMS.

If disabled (0), the shmget function will not return an error, but the memory segment will be allocated from system pageable memory instead.

Value

For a typical environment the values can be as follows.

vm: gh_fail_if_no_mem = 0

System Specific Tuning | 4-23

INSECURE_BIND

Description

When Oracle Parallel Server (OPS) or Informix with IPC streams (ipcstr) is used, it is necessary to enable insecure binding to sockets.

Value

For a typical environment the values can be as follows.

generic: insecure_bind = 1

VM_SWAP_EAGER or /SBIN/SWAPDEFAULT

Description

When the minimum amount of swap space required (512MB internal memory needs 1GB of swap space is used, more than 1GB of internal memory needs a one to one relationship regarding the size of swap space) it is necessary to switch to lazy (or deferred) swap mode.

Value

On pre Tru64 UNIX V5.0 systems you must remove (or rename) /sbin/swapdefault. On Tru64 UNIX V5.0 or later:

generic: vm_swap_eager = 0

/DEV/TIMEDEV

Description

When Oracle timed statistics is used, a great deal of system time can be used due to a large number of calls to the gettimeofday function. Create a special file to use another mapping mechanism to the kernel’s date and time structures. Use the following command to do so.

mknod /dev/timedev c 15 0


SUN / Fujitsu Siemens – Solaris

NBUF/NPROC

Do not set NBUF and NPROC on Solaris. This can cause problems.

PT_CNT

Description

Specifies the number of pseudo terminals. Refer to “General Kernel Parameters” in Chapter 3, “UNIX Kernel Parameters.”

After changing this parameter the devices have to be generated this can be done through the command boot –r.

PRIORITY_PAGING/ FASTSCAN/ MAXPGIO

Description

These parameters increase performance and influence the priority paging mechanism. After changing these parameters a process memory page gets higher priority then a file system buffer page.

Value

For a typical environment, the values can be as follows:

PRIORITY_PAGING = 1 FASTSCAN = 131072 MAXPGIO = 16384

user's guide for kernel tuning - baansupport.com iv c4 kernel tuning guide.pdf · hp-ux....

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