Memory Requirement of the SAP Web Dispatcher
The SAP Web dispatcher must reserve as much memory as possible to store large tables.
Server Tables
The server tables contain the configuration values from the three files, info.icr, groups.icr, and urlprefix.icr (or fetched from the application servers).
The following formula estimates roughly how much memory is required:
Memory Requirement = (S × NS + G × NG + U × NU) × 2 Bytes
The letters have the following meaning:
Variable |
Parameter Value |
Default Value |
S |
wdisp/max_servers |
128 |
NS |
wdisp/max_server_name_len |
64 |
G |
wdisp/max_server_groups |
128 |
NG |
wdisp/max_server_group_name_len |
20 |
U |
wdisp/max_url_map_entries |
300 |
NU |
wdisp/max_url_map_path_len |
256 |
For the default settings this comes to 87552 bytes, which is negligible.
Session ID Table
In this table each SAP Web dispatcher keeps to the server names of the active sessions, provided that the dispatcher is working with external session IDs or J2EE session IDs.
The memory consumption of the table depends on the maximum number of entries (profile parameter wdisp/HTTP/max_session_tab_entries as well as the use of Unicode.
Maximum number of entries |
Memory Requirement ASCII |
Memory Requirement Unicode |
|---|---|---|
10000 |
1.7 MB |
2.0 MB |
50000 (default) |
8.5 MB |
9.7 MB |
100000 |
17.0 MB |
20.1 MB |
MPI Parameters
The MPI memory is a pure communication memory. This means the Web dispatcher reads the data from a partner into this memory and then forwards this data to another partner. Once the data has been forwarded the memory is free again. The whole MPI memory (mpi/total_size_MB) is split into blocks of a fixed size of the value of mpi/buffer_size. The standard value of mpi/total_size_MB is 80 (megabytes). The standard value of mpi/buffer_size is 65536 (bytes).
IP Mapping Tables for Stateful SSL Connections
The SSL client IP table is needed for end-to-end SSL and contains the mapping of client IP to the application server: