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The buffer pool is used to keep copies of popular database blocks in memory to minimize disk I/O. There are a number of complex data structures involved, but the most important are the buffers themselves and the buffer headers. Each buffer contains a copy of one database block and is the same size as a database block. For each buffer, there is a buffer header that describes what is in the buffer and some information about it (updated or not, which database block it is, whether the buffer is locked or not, and so forth). The buffer headers are around 150 bytes long. There are two different buffer pools in the progress database. They are:

Whenever a user requests data from the database, for the very first time, the data is fetched from the disk and stored in the buffer pool. Subsequent requests for the same data are catered from the buffer pool. Sometimes, the buffer pool may not be able to cater the data due to unavailability of the data, buffer overhead etc leading to an increase in disk I/O and a decrease in the efficiency of the buffer pool. This may lead to over-utilization of the disk. Therefore, it is essential to monitor the buffer pools of the Progress database server. The ProBuffActivityTest test helps administrators in this regard!

This test auto-discovers the buffer pools in the Progress database server and for each buffer pool, this test reports how well the read/write operations were performed on the database block? In addition, this test also reports the rate at which the read/write operations were performed on the disk. Using this test administrators can figure out how well the buffer pools are utilized and optimize the buffer pools so that the disk I/O is reduced. The query response time to retrieve the data can also be improved considerably.

Output of the test : One set of results for every buffer cache of the target Progress database server that is to be monitored.

Measurement	Description	Measurement Unit	Interpretation
Buff_logic_read	Indicates the rate at which read operations were performed on the database block of this buffer pool during the last measurement period.	Reads/sec	A high value is desired for these measures. A low value is indicative of ineffective cache usage, typically caused by improper cache size.
Buff_logic_write	Indicates the rate at which write operations were performed on the database block of this buffer pool during the last measurement period.	Writes/sec
Buff_OS_read	Indicates the rate at which the client requests to this buffer pool directly executed on and read the database blocks from the physical disk.	Reads/Sec	Physical database reads can cause processing overheads to escalate, thereby affecting database performance. These transactions therefore have to be minimized. A high value could indicate that direct disk accesses are occurring too frequently. This in turn implies poor cache usage. You may consider resizing your cache to accommodate more number of queries, so that direct disk reads are reduced.
Buff_OS_write	Indicates the rate at which the database blocks were directly written to the disk instead of this buffer pool.	Writes/Sec
Buff_hit_ratio	Indicates the percentage of database blocks that were served from this buffer pool (i.e., without requiring a read from the disk).	Percent	A high value is desired for this measure. A sudden/gradual decrease in the value of this measure is a cause of concern as this may lead to an abnormal increase in the disk I/O.