Input/Output Analyses

Input/Output analyses show information about the level of run delay from the restart of the server, and calculate the average delay of read, write and the common input/output for each individual file of the database.

The input/output analyses feature is available on the Performance panel in the Administration panel.

CASE SUMMARY The IT department of the Tecta company received a complaint from users about a slow performance of the SI_TECTA database. The person responsible from the IT department carries out several performance monitorings. One of them is also the input/output analysis. The person responsible does this in the following way: Selecting the database on server Analysing the level of run delay from the restart of the server. Analysing the database files.

1. Selecting the database on server

From the list of databases on server, the person responsible selects the database for which they want to carry out an input/output analysis, by clicking the checkbox .

HINT You can select several databases, for which you will run the analyses.

WARNING If the database you are looking for is not on the list of database, click the Refresh databases button. For a detailed description, read chapter Refreshing the database list.

Then, the person responsible clicks the Analyse button.

The program returns the result of the input/output analysis for the selected databases.

2. Analysing the level of run delay from the restart of the server

Based on the results of the input/output analysis, the person responsible checks how long it takes for the system to read or write data from the computer data storage or disc. The information is written in the ReadLatency and WriteLatency fields.

HINT   The read and write latency parameters show how long it takes for the system to read data from the memory storage or disc. Higher latency means that the system needs more time to access data, which can negatively affect the total performance and responsiveness of the system. Low latency means that the system can read data faster, which leads to a better capacity and performance of the applications.

WARNING If the ReadLatency and WriteLatency parameters are higher than 10ms, attention must be paid to potential problems on the disk or procedure problems.

In this case, the ReadLatency and WriteLatency parameters are lower than 10ms, which is why the person responsible dismisses the possibility that the slow performance of the database is caused by the disc.

3. Analysing the database files

In the second part of the input/output analysis, a table with data about the average value of read and write latency parameters from the database files is displayed.

HINT mdf is the key file, which contains all data that is in the database. The ldf file marks the changes that were made in the database. Which data and in what capacity is written in the ldf file depends on preliminary settings. For more, read chapter Setting log changes.

In this case, the ReadLatency and WriteLatency parameters are lower than 10ms, which is why the person responsible dismisses the possibility that the slow performance of the database is caused by the mdf and ldf files.