Configuring The Informix Environment

Message and Log Files

The INFORMIX-OnLine log and console files are both UNIX flat files, which are specified in the Informix onconfig file, via the CONSOLE and MSGPATH onconfig parameters.
The message log file contains routine informational messages, assertion failure messages, messages requiring administrative action to be taken, and fatal error messages.
The console message file is used to display routine status messages and diagnostic messages.

Connectivity Files

The INFORMIX-OnLine engine uses a number of files to define its communications protocol and network interface. This allows the OnLine engine to communicate and transfer data to and from various client connections. This communication requires the proper entries in the following UNIX environment variables and key files:

  • INFORMIXSERVER: The INFORMIXSERVER UNIX environment variable indicates which database server to connect to by default.
  • /etc/hosts: The /etc/hosts file contains an entry for every machine on the network that will connect to the INFORMIX engine.
  • /etc/services:This contains an entry for each service that will use TCP/IP as a connection protocol.
  • $INFORMIXDIR/etc/sqlhosts: This contains information that allows an INFORMIX-OnLine database client/server connection to occur from any client on the network.

The Root dbspace

The root dbspace is a special dbspace that the INFORMIX-OnLine engine creates during disk initialization.

onconfig Parameters

ALARMPROGRAM

BUFFERS

BUFFERPOOL

The BUFFERPOOL configuration parameter specifies the default values for buffers and LRU queues in a buffer pool for both the default page size buffer pool and for any non-default pages size buffer pools.
Example

BUFFERPOOL default,lrus=8,buffers=5000,lru_min_dirty=50,lru_max_dirty=60
BUFFERPOOL size=2K,buffers=5000,lrus=8,lru_min_dirty=50,lru_max_dirty=60
BUFFERPOOL size=6K,buffers=3000,lrus=8,lru_min_dirty=50,lru_max_dirty=60

The order of precedence for the BUFFERPOOL configuration parameter settings is:
1. The BUFFERPOOL size line, for example:

BUFFERPOOL size=2K,buffers=5000,lrus=8,lru_min_dirty=50,lru_max_dirty=60

2. Any deprecated parameters in the ONCONFIG file:
* BUFFERS
* LRUS
* LRU_MAX_DIRTY
* LRU_MIN_DIRTY

3. The BUFFERPOOL default line, for example:

BUFFERPOOL default,lrus=8,buffers=5000,lru_min_dirty=50,lru_max_dirty=60

4. Database server defaults.

CHUNKS

CKPTINTVL

CLEANERS

CONSOLE

DBSERVERNAME

DBSPACES

DBSPACETEMP

LOGBUFF

LOGFILES

LRUS

LRU_MAX_DIRTY

LRU_MIN_DIRTY

LTXHWM

LTXEHWM

MSGPATH

MULTIPROCESSOR

NETTYPE

NUMAIOVPS

NUMCPUVPS

PHYSBUFF

PHYSFILE

RESIDENT

If your system supports forced residency, this parameter can force the resident portion of the OnLine shared memory to never be swapped. Be careful with this parameter. If you force residency while the system needs to swap, and not enough memory is left to perform the system processes, you will have serious performance problems. The default is 0 (no forced residency). To force residency, set this parameter to 1.

ROOTNAME

ROOTOFFSET

ROOTPATH

ROOTSIZE

SINGLE_CPU_VP

Initializing the OnLine Engine

Two types:

  • initial use: oninit -iy
  • bring up an existing instance of INFORMIX: oninit

Creating Additional dbspaces

Informix dbspaces can be a raw device (UNIX space set aside for a process to access the space directly without the overhead of the UNIX kernel handling the I/O) or a cooked UNIX file.

Cooked Files

An Informix cooked file is a UNIX file, so UNIX manages all of the I/O to the dbspace

Raw Devices

A raw device is a "character-special" file that can be accessed using direct memory access (DMA). This type of access allows Informix to bypass the UNIX file management and manage the I/O to the device via a direct transfer to and from shared memory.

Create dbspaces

After the raw devices or the cooked files have been created, you can create the dbspaces. Informix dbspaces can be created via the ON-Monitor tool or via command-line utilities.

The following command creates a 100MB dbspace called big_boy, starting at an offset of 8KB into the raw device:

onspaces -c -d big_boy -p /dev/raw_chunk -o 8 -s 100000

Managing the Logs

The DBA needs to ensure that every effort has been taken to manage the logs properly and limit the risk of losing the logs.

Starting and Stopping the OnLine Engine

oninit Brings an offline instance online, leaving disk/data intact.
oninit -i Initializes OnLine
{onmode -k}} Brings OnLine offline

onmonitor tool

More details here onmonitor

Bibliography
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