Adaptive Server uses different page sizes for cache and buffer pools:
Memory pages – (max memory, total logical memory, and so on) are multiples of 2K
Procedure cache – configured in 2K pages
Buffer cache – expressed in units of logical page size
Large I/O – scaled in terms of extents (each extent is 8 pages). For example, if Adaptive Server is configured for an 8K logical page size, large I/O uses a read or write that is 64K.
If you start Adaptive Server and the caches are defined with buffer pools that are not valid for the current logical page size, all memory for such inapplicable buffer pools is reallocated when configuring caches to the default buffer pool in each named cache.
Be careful in how you set up logical page sizes and what you allow for in the buffer pool sizes.
Logical page size |
Possible buffer pool sizes |
---|---|
2K |
2K, 4K, 16K |
4K |
4K, 8K, 16K, 32K |
8K |
8K, 16K, 32K, 64K |
16K |
16K, 32K, 64K, 128K |