.
contact contact

B.08.30 / Release Notes / Installation

HP-UX Kernel Parameters

 
.
  Eloquence B.08.30 may require the configuration of additional HP-UX kernel parameters or adjustment of previously configured kernel parameters.

As of Eloquence B.08.00 the eloqdb database server is a multi-threaded process that opens a set of files (volume files, log files, etc), allocates its internal database BufferCache, and waits for incoming client connections via TCP sockets. For each client it creates an OS level thread and by default it uses Sys V IPC semaphores and shared memory to communicate with the clients, if they are on the same host.

The following sections discuss HP-UX kernel parameters involved.

You may have to increase some of the HP-UX kernel parameters beyond the default values, depending on your number of eloqdb servers and their eloqdb.cfg settings like Threads or BufferCache, for example.

Note that the discussion below only explains the requirements for the eloqdb database server(s). When adjusting kernel parameters, you need to also take into account any requirements by other applications as well as the operating system itself. So you will typically add to existing settings, to be on the safe side.

Processes / Threads

  • nproc - limits the number of processes allowed to exist simultaneously
  • maxuprc - limits the maximum number of concurrent user processes per user
  • nkthread - limits the number of threads allowed to run simultaneously
  • max_thread_proc - defines the maximum number of concurrent threads allowed per process.
The default settings for nproc and maxuprc should typically be sufficient. However, you may need to increase the nkthread and or the max_thread_proc parameters depending on number of servers or eloqdb.cfg [config] Threads.

Each eloqdb server process creates a small number of internal OS threads, typically below 10, and one additional OS thread for every concurrent DB client connection (regardless of the number of DBOPENs by each client).

Use

nkthread        >= SUM of "10 + max number of clients (Threads)" per eloqdb
max_thread_proc >= MAX of "10 + max number of clients (Threads)" per eloqdb
In other words: nkthread depends on the total number of client threads across your eloqdb servers, whereas max_thread_proc depends on the eloqdb server with the largest number of client threads.

For example:

eloqdb server A: Threads = 1000
eloqdb server B: Threads =  300
eloqdb server C: Threads =  200

nkthread        >= 1530  ( 3*10+1000+300+200 )
max_thread_proc >= 1010  ( 10+1000 )

Files / Sockets

  • maxfiles_lim - hard maximum number of file descriptors per process
Each eloqdb server opens a typically small to moderate number of files, depending on your specific eloqdb.cfg settings. This includes the DATA and LOG volumes, LogFile, StatFile, SessionStatFile, and forward logs, for example. However, each eloqdb server also listens for incoming TCP connections on the ports [Server] Service (and ServiceHttp), accepting up to [config] Threads concurrent socket connections by DB clients.

The default maxfiles_lim by HP-UX is typically sufficient, unless you have a server with a very large maximum number of concurrent clients.

Sys V IPC semaphores

  • semmns - number of System V IPC system-wide semaphores
  • semmni - number of System V IPC system-wide semaphore identifiers
  • semmnu - maximum number of System V IPC undo structures for processes
  • semume - maximum number of System V IPC undo entries per process
Each eloqdb server process uses Sys V IPC semaphores and shared memory for communicating with the database clients running on the local system, unless eloqdb.cfg is configured for [Server] EnableIPC = 0. For remote database clients, only the TCP socket connection is used.

When using Sys V IPC semaphores, the eloqdb server allocates a semaphore identifier with 2 semaphores for each concurrent client connection and also makes use of SEM_UNDO operations for each of these client sessions.

Unless you have a large number of eloqdb servers, the HP-UX default for semmnu will typically be sufficient. However, you may need to increase the semmns, semmni and especially the semume setting in some cases.

Use

semmni >= SUM of "max number of clients (Threads)" per eloqdb
semmns >= SUM of 2 * "max number of clients (Threads)" per eloqdb
semmnu >= number of eloqdb servers
semume >= MAX of "max number of clients (Threads)" per eloqdb
In other words: semmni and semmns depend on the total number of client threads across your eloqdb servers, whereas semume depends on the eloqdb server with the largest number of client threads (and semmnu depends on the number of eloqdb servers).

For example:

eloqdb server A: Threads = 1000
eloqdb server B: Threads =  300
eloqdb server C: Threads =  200

semmni >= 1500  ( 1000+300+200 )
semmns >= 3000  ( 2*1000+2*300+2*200 )
semmnu >= 3
semume >= 1000

Sys V IPC shared memory

  • shmmni - number of System V shared memory segment identifiers in the system
  • shmmax - maximum size (in bytes) for a System V shared memory segment
  • shmseg - maximum number of System V shared memory segments per process
Each eloqdb server process uses Sys V IPC semaphores and shared memory for communicating with the database clients running on the local system, unless eloqdb.cfg is configured for [Server] EnableIPC = 0. For remote database clients, only the TCP socket connection is used.

For EnableIPC=2 (the default) the eloqdb server allocates a single shared memory segment for communicating with local database clients. The segment size depends on the configured max number of clients, ie [config] Threads. For EnableIPC=1 the eloqdb server allocates a separate 32 KB segment for each database client.

Unless you have a large number of eloqdb servers or use EnableIPC=1, the HP-UX defaults for shmmni and shmseg will typically be sufficient.

With EnableIPC=2 use

shmmni >= number of eloqdb servers
With EnableIPC=1 use
shmmni >= SUM of "max number of clients (Threads)" per eloqdb
          plus number of eloqdb servers

shmseg >= MAX of "max number of clients (Threads)" per eloqdb
Using EnableIPC=2 is recommended for efficiency reasons.

Process memory / Address space

  • maxdsiz, maxdsiz_64bit - maximum size (in bytes) of the data segment for any user process
  • max_mem_window - maximum number of group-private 32-bit shared memory configurable by users
The memory allocation of the eloqdb servers depends on a number of factors, including the eloqdb.cfg settings for [Config] BufferCache and [Config] Threads, and differs for the 32-bit and 64-bit server.

The data segment sizes of processes are limited by the maxdsiz or maxdsiz_64bit kernel parameters. For 32-bit processes there are also architecture-specific limitations on the address space available for global shared memory segments.

The 32-bit eloqdb servers allocate stack space for OS level threads handling concurrent client sessions from their data segment and memory for the dedicated BufferCache from the shared memory address space. Depending on your eloqdb server with the largest number of concurrent client sessions (limited by [Config] Threads), you may need to increase the maxdsiz parameter or switch to using the 64-bit eloqdb program.

Depending on your number of eloqdb server instances and their settings for [Config] BufferCache, you may also run into limits or fragmentation issues with the global shared memory address space. This may require to switch to using HP-UX memory windows or the 64-bit eloqdb program.

The 64-bit eloqdb servers do not only allocate stack space for OS level threads handling concurrent client sessions from their data segment, but also allocate memory for the dedicated BufferCache this way. They only use shared memory for the client communication (with EnableIPC > 0).

Depending on your eloqdb server settings for [Config] Threads as well as [Config] BufferCache, you may need to increase the maxdsiz_64bit.

Note that the BufferCache memory is allocated during startup of the eloqdb server process whereas the stack space for OS level threads handling concurrent client sessions grows as these sessions connect.

Note that HP-UX on PA-RISC uses 64 KB stack size per thread, whereas HP-UX on Itanium uses 256 KB stack size per thread.

HP-UX evp driver is required

The Eloquence database requires the HP-UX evp driver enabled in the kernel configuration. The following commands may be used to verify if the evp driver is configured:
lsdev -C pseudo | grep evp
ls /dev/poll
If the evp driver is configured it is listed in the lsdev output and the /dev/poll device file is present. If not, the evp driver needs to be enabled in the kernel configuration or the database server will not start.

Upgrading from Eloquence versions before B.08.00

When upgrading from Eloquence versions before B.08.00, please refer to the HP-UX kernel config section of the Eloquence B.08.00 Release Notes.


 
 
 
  Privacy | Webmaster | Terms of use | Impressum Revision: 2018-06-26  
  Copyright © 1995-2021 Marxmeier Software AG