Hierarchy
SAP_BASIS (Software Component) SAP Basis Component⤷
BC-DB-INF (Application Component) Informix⤷
STUI (Package) Informix Database Monitor
Basic Data
| Data Element | PHYSBUFF |
| Short Description | Size of the two physical log buffers |
Data Type
| Category of Dictionary Type | D | Domain |
| Type of Object Referenced | No Information | |
| Domain / Name of Reference Type | SINT4_NOS | |
| Data Type | INT4 | 4-byte integer, integer number with sign |
| Length | 10 | |
| Decimal Places | 0 | |
| Output Length | 10 | |
| Value Table |
Further Characteristics
| Search Help: Name | ||
| Search Help: Parameters | ||
| Parameter ID | ||
| Default Component name | ||
| Change document | ||
| No Input History | ||
| Basic direction is set to LTR | ||
| No BIDI Filtering |
Field Label
| Length | Field Label | |
| Short | 0 | |
| Medium | 0 | |
| Long | 0 | |
| Heading | 0 |
Documentation
Definition
Online uses the shared memory physical log buffers for tempory storage of "before-images" of dbspace pages. The "before images" in the physical log enable Online to restore consistency to its databases after a system failure.
The size of the two physical log buffers, located in shared memory, are always equal. By double buffering, user threads are able to write to the active physical log buffer while the other buffer is being flushed to the physical log on disk.
The PHYSBUFF parameter in the ONCONFIG* file located in the directory $INFORMIXDIR/etc specifies the size of the physical log buffers. Small buffers can create problems is you store records that are larger than the size of the buffers. The minimum value is 1. The maximum is n >= (page size). Recommended size is 16 pages.
To determine if tuning is needed see the help description for the PhysLog written/IO parameter.
History
| Last changed by/on | SAP | 20010130 |
| SAP Release Created in |
