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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.
Number of pages added to the MLRU queuesThe page-cleaner threads flush the modified buffers in an MLRU queue to disk. To specify the point at which cleaning begins, use the BUFFERPOOL configuration parameter to specify a value for lru_max_dirty, which limits the number of page buffers that can be appended to an MLRU queue.

Number of pages added to the MLRU queues

The page-cleaner threads flush the modified buffers in an MLRU queue to disk. To specify the point at which cleaning begins, use the BUFFERPOOL configuration parameter to specify a value for lru_max_dirty, which limits the number of page buffers that can be appended to an MLRU queue.

The initial setting of lru_max_dirty is 60.00, so page cleaning begins when 60 percent of the buffers managed by a queue are modified.

In practice, page cleaning begins under several conditions, only one of which is when an MLRU queue reaches the value of lru_max_dirty. For more information about how the database server performs buffer-pool flushing, see Flush data to disk.

The following example shows how the value of lru_max_dirty is applied to an LRU queue to specify when page cleaning begins and thereby limit the number of buffers in an MLRU queue.

Buffers specified as 8000
lrus specified as 8
lru_max_dirty specified as 60 percent

Page cleaning begins when the number of buffers in the MLRU 
   queue is equal to lru_max_dirty.

Buffers per lru queue = (8000/8) = 1000

Max buffers in MLRU queue and point at which page cleaning 
   begins: 1000 x 0.60 = 600