Document Type | Technical Information
Category | Installation
Applicable Product Versions | Tibero6, Tibero7
Document Number | TINTI042
Overview
This document describes the memory configuration method for Tibero7.
Method
1. Memory Configuration Parameters
| Parameter | Description |
|---|---|
| TOTAL_SHM_SIZE | Parameter that sets the total size of shared memory used by the instance. Composed of database buffer, Redo log buffer, SQL Cache, and data dictionary Cache. A certain level of memory allocation is necessary for normal operation of applications. Tibero configures TOTAL_SHM_SIZE at about 40%~50% of the system physical memory and adjusts it later through monitoring. |
| DB_CACHE_SIZE | Parameter that sets the size of the database Cache buffer. For single instances, it is set to about 2/3 of TOTAL_SHM_SIZE; for TAC instances, about 1/2. The appropriateness of the size is judged based on buffer Cache hit rate trends. |
| LOG_BUFFER | Parameter that sets the size of the memory area used to store logs. The default value is 10M, and it should be set to a sufficient size considering the workload characteristics. |
| MAX_SESSION_COUNT | Composed of the combination of WTHR_PROC_CNT (parameter setting the number of working processes) and _WTHR_PER_PROC (parameter setting the number of working threads included in one working process, default value 10). |
2. Parameter Value Calculation
"The total shared memory (TOTAL_SHM_SIZE) size is calculated as DB_CACHE_SIZE + LOG_BUFFER(10M) + 20M (initial startup allocation area) + number of sessions (WTHR_PROC_CNT * _WTHR_PER_PROC) * 2M"
It is recommended to set a value slightly larger than this calculated amount.
- DB_CACHE_SIZE: Generally set indirectly to about 2/3 of TOTAL_SHM_SIZE for single instances, and about 1/2 for TAC instances.
- LOG_BUFFER: If not set separately, the default value is 10M.
- MEMORY_TARGET - TOTAL_SHM_SIZE = PGA area automatically set (PGA area manages SESSION information, variable information, etc.)
3. Example of Applying Parameter Values
-- TIP file configuration
MAX_SESSION_COUNT=500
TOTAL_SHM_SIZE=2600M
MEMORY_TARGET=4G
In this configuration
Listener port = 8629
*****************************************************
* Warning !!!
* Shared memory size is too small.
* Enlarge shared memory size(TOTAL_SHM_SIZE).
* Current size: 2726297600 bytes
* Minimum size: 2922548280 bytes
*****************************************************
Tibero 7
TmaxData Corporation Copyright (c) 2008-. All rights reserved.
Tibero instance started up (NORMAL mode).Although starting with TOTAL_SHM_SIZE=2600M is possible, a warning message may occur.
This is because TOTAL_SHM_SIZE is set insufficiently as DB_CACHE_SIZE (2600 * 0.67 = 1742M) + LOG_BUFFER (10M) + initial startup (20M + a) + number of sessions (500 * 2M = 1000M) = 2772M + a.
-- TIP file configuration
MAX_SESSION_COUNT=500
TOTAL_SHM_SIZE=3G
MEMORY_TARGET=4G
After modifying TOTAL_SHM_SIZE to 3G
Tibero 7
TmaxData Corporation Copyright (c) 2008-. All rights reserved.
Tibero instance started up (NORMAL mode).With TOTAL_SHM_SIZE=3G setting, no warning message occurs.