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Parameters in the Configuration File Cache Section

The parameters in the Cache section provide configuration information for Siebel Analytics Server caching. For information about caching, see the chapter on query caching in Siebel Analytics Server Administration Guide.

ENABLE

Specifies whether the cache system is enabled. When set to OFF, caching is disabled. When set to ON, caching is enabled.

Example: ENABLE = OFF ;

DATA_STORAGE_PATHS

Specifies the directory paths for where the cached data is stored and the maximum capacity in bytes, kilobytes, megabytes or gigabytes. The maximum capacity for each path is 4 GB. Each directory listed needs to be an existing, fully-qualified, writable directory pathname, with double quotes ( " ) surrounding the pathname. Specify mapped directories only. UNC path names and network mapped drives are allowed only if the service runs under a qualified user account. To change the account under which the service is running, see Changing the Account Under Which a Windows Service Runs. For optimal performance, the directories specified should be on high performance storage systems.

NOTE:  Siebel Analytics Servers defined as Clustered Servers do not share cached data. The DATA_STORAGE_PATHS entry needs be unique for each server defined as a cluster participant.

Specify multiple directories with a comma separated list. If you specify more than one directory, they should reside on different physical drives. (If you have multiple cache directory paths that all resolve to the same physical disk, both available and used space may be double-counted.)

Syntax: DATA_STORAGE_PATHS = "<full_directory_path_1>" sz[, "<full_directory_path_2>" sz{, "<full_directory_path_n>" sz}] ;

Example: DATA_STORAGE_PATHS = "d:\SiebelAnalytics\cache" 100MB, "f:\SiebelAnalytics\cache" 200MB ;

NOTE:  Specifying more than one directory per drive does not improve performance because file input and output (I/O) takes place through the same I/O controller. In general, specify only one directory per disk drive. Specifying multiple directories on different drives may improve the overall I/O throughput of the Siebel Analytics Server internally by distributing I/O across multiple devices.

The disk space requirement for the cached data depends on the number of queries that produce cached entries and the size of the result sets for those queries. The query result set size is calculated as row size (or the sum of the maximum lengths of all columns in the result set) times the result set cardinality (that is, the number of rows in the result set). The expected maximum should be the guideline for the space needed.

This calculation gives the high-end estimate, not the average size of all records in the cached result set. Therefore, if a result set's size is dominated by variable length character strings and if those strings' lengths have a normal distribution, you would expect the average record size to be about half of the maximum record size.

METADATA_FILE

Specifies the name of the file that contains information about queries for which data is cached. The filename needs to be a fully qualified pathname with a .dat extension.

NOTE:  Siebel Analytics Servers defined as Clustered Servers do not share cached data. The METADATA_FILE entry needs be unique for each server defined as a cluster participant.

Example: METADATA_FILE = "d:\SiebelAnalytics\metadata_file.dat" ;

REPLACE_ALGORITHM

Specifies the algorithm used to replace existing entries in the cache. Currently, the only supported algorithm is LRU (Least Recently Used).

Example: REPLACE_ALGORITHM = LRU ;

BUFFER_POOL_SIZE

Specifies the size of the buffer pool to use to store information from the cache metadata file in memory to improve the cache response time. Specify KB for kilobytes, MB for megabytes, and no units for bytes.

Example: BUFFER_POOL_SIZE = 1 MB ;

MAX_ROWS_PER_CACHE_ENTRY

Specifies the maximum number of rows in a query result set to qualify for storage in the query cache. If the query results have more rows than specified, the results are not stored in the cache. When set to 0, there is no limit to the number of rows per cache entry.

Example: MAX_ROWS_PER_CACHE_ENTRY = 100000 ;

MAX_CACHE_ENTRY_SIZE

Specifies the maximum size for a cache entry. Potential entries that exceed this size are not cached. The default size is 1 MB. Specify GB for gigabytes, KB for kilobytes, MB for megabytes, and no units for bytes.

Example: MAX_CACHE_ENTRY_SIZE = 1 MB ;

MAX_CACHE_ENTRIES

Specifies the maximum number of cache entries allowed in the query cache. When the limit is reached, old entries are replaced by new entries according to the mechanism specified by the REPLACE_ALGORITHM parameter. The actual limit of cache entries might vary slightly depending on the number of concurrent queries. The default value is 1000.

Example: MAX_CACHE_ENTRIES = 1000 ;

METADATA_BACKUP_FREQUENCY_MINUTES

Specifies the amount of time, in minutes, between each backup of the cache metadata file. When caching is enabled, the cache metadata file is always backed up upon server startup and is backed up again at the interval specified in the parameter. The server automatically uses the backup file after a sudden server shutdown occurs (for example, a power failure or a crash). The backup file is created in the same directory as the cache metadata file and is named the same as the cache metadata file with a .bak extension appended to the name.

When the backup file is used, any entries cached after the backup file was created are automatically purged from the cache. If any entries have been purged or aged out of the cache after the backup file was created, those entries are not recovered. To force the creation of a new cache metadata backup file, cleanly shut down and restart the server as described in the chapter on administering the query environment in Siebel Analytics Server Administration Guide.

The default value is 1440 minutes (24 hours). The maximum value is 10080 minutes (7 days). A value of 0 indicates that no periodic backups of the cache metadata file are performed.

Example: METADATA_BACKUP_FREQUENCY_MINUTES = 1440 ;


 Siebel Analytics Installation and Configuration Guide
 Published: 09 September 2004