Collecting Disk Performance Data

This section describes some common tools for measuring and monitoring disk performance. The following are some key terms that you need to know for this section:

  • Block I/O: The reads and writes that are held in the buffer cache (buffered) and then transferred in fixed-size blocks.

  • File I/O: The I/O access to a physical disk, which does not include virtual memory. It includes filesystem I/O, system I/O, raw I/O, and block I/O.

  • Logical I/O: The read or write system call made by an application to the filesystem. The call results in physical I/O if the data is not in the buffer cache.

  • Physical I/O: Data transferred from memory to disk, or vice versa. Physical I/O includes both file I/O and virtual memory I/O.

  • Raw I/O: ...

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