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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Administrator's GuideThe HCL OneDB™ Administrator's Guide provides the information required to administer HCL OneDB™.
Disk, memory, and process management
Shared memoryThese topics describe the content of database server shared memory, the factors that determine the sizes of shared-memory areas, and how data moves into and out of shared memory.
Database server thread access to shared buffersDatabase server threads access shared buffers through a system of queues, using mutexes and locks to synchronize access and protect data.
FIFO/LRU queuesA buffer holds data for the purpose of caching. The database server uses the least-recently used (LRU) queues to replace the cached data. HCL OneDB™ also has a first-in first-out (FIFO) queue. When you set the number of LRU queues, you are actually setting the number of FIFO/LRU queues.
Components of LRU queueEach LRU queue is composed of a pair of linked lists.

Components of LRU queue

Each LRU queue is composed of a pair of linked lists.

The linked list pairs are as follows:

FLRU (free least-recently used) list, which tracks free or unmodified pages in the queue
MLRU (modified least-recently used) list, which tracks modified pages in the queue

The free or unmodified page list is called the FLRU queue of the queue pair, and the modified page list is called the MLRU queue. The two separate lists eliminate the task of searching a queue for a free or unmodified page. The following figure illustrates the structure of the LRU queues.

This figure shows an LRU queue that is composed of two queues, FLRU 1 and MLRU 1. FLRU 1 contains a pointer to an unmodified page and a pointer to an empty page. MLRU 1 contains a pointer to a modified page. — Figure 1: LRU queue