To save data in a file in the cache modes Main Memory Cache with Swapping, Flat File Cache per Application Server, or Cross-Application Server (see Cache Mode ), the following specifications must first be set:
By pressing Logical File Names in the Cache Monitor screen, you can access the complex table maintenance for logical file paths and names. The table maintenance consists of several subdialogs (views). SAP delivers some of the settings required for this.
You need to check these settings and make any necessary adjustments for your file system before using the persistent OLAP cache with a flat file as a background store.
Note that these assignments are subject to settings made for the transport connection (You need a request that can be transported).
The following section gives an overview of the subdialog in the table maintenance using an example configuration. For more information about the procedure, see Defining Logical Path and File Names .
You can choose the following subdialogs using the dialog structure:
Logical File Path Definition
The (platform-independent) logical file path is evaluated at runtime to generate the (platform-dependent) physical path (see Assignment of Physical Paths to Logical Path).
Two examples of this are:
Assignment of Physical Paths to Logical Path
At runtime, the physical path assigned to the corresponding operating system is generated from the logical file path.
Since the physical path is platform-dependent, it has to be set by the customer. The closer the file is to the application server or, with the cross-application server cache mode, to the application server, the faster it can be found and read.
Log(ical) path: BW_OLAP_CACHE
Name: BW OLAP Cache
Syntax group: UNIX (all Unix platforms)
Phys(ical) path: /usr/<SYSID>/global/<FILENAME> (You can choose the path up to <FILENAME> according to your own configuration.)
If you cannot find the relevant syntax group for file names and paths for your operating system, you can define your own (see Syntax Group Definition and Assignment of Operating System to Syntax Group).
The <FILENAME> parameter must always be set for the physical file name (see Logical File Name Definition, Cross-Client). At runtime, the complete platform-specific file name is automatically formed from the physical path and the physical file name.
Logical File Name Definition, Cross-Client
At runtime, a complete platform-specific file name including the path is generated for a (platform-independent) logical file name.
In the following example, cache data is stored on an application server:
Log(ical) file: BW_OLAP_CACHE (we recommend using the delivered attributes for the logical file).
Name: BW OLAP cache files
Phys(ical) file: CACHE_<HOST>_<SYSID>_<PARAM_1>
Data format: BIN (binary)
Application area: BW (Business Information Warehouse)
Log(ical) path: BW_OLAP_CACHE (see Logical File Path Definition).You can use input help for this.
In the following example, cache data is stored cross-application server:
Log(ical) file: BW_OLAP_CACHE_SPAN
Name: BW OLAP cache cross-application server
Phys(ical) file: CACHE_<SYSID>_<PARAM_1>
Data format: BIN
Application area: BW
Log(ical) path: BW_OLAP_CACHE_SPAN
Note that there is a specific schema for the physical file name:
CACHE_<HOST>_<SYSID>_<PARAM_1>
CACHE_<SYSID>_<PARAM_1>
The following table provides an overview of variables that are not replaced with current values until runtime:
Variables in Physical File Names
Variable | Meaning |
---|---|
<HOST> |
Computer/server name (according to SY-HOST) If the data is stored cross-application server, this variable is not required. |
<SYSID> |
System ID This variable serves to distinguish between systems, if two different BW systems are running on one application server for example, thus ensuring that they do not over-write each other. |
<PARAM_1> |
External parameter 1 (sequential number in HEX) |
Definition of Variables
If you want to use variables in physical file names and paths, you can define these by choosing New Entries.
Syntax Group Definition
You can define a new syntax group for operating systems with the same syntax for file names and paths by choosing New Entries.
Syntax group: UNIX
Name: All Unix platforms
Length (of file name)
Extension: Choose this option if the data format for the logical data name is allowed to be the file name extension for this syntax group
Active: Choose this option if the operative system for this syntax group is used in the available system configuration.
Assignment of Operating System to Syntax Group
If required, you can assign your operating system to a syntax group by choosing New Entries.
OP system: SunOS
Name: SUN Unix