cifsiostat

cifsiostat [-h] [-k] [-m] [-t] [-V] [delay [count]]

-h
    Display help text and exit.

-k
    Display statistics in kilobytes per second instead of bytes per second.

-m
    Display statistics in megabytes per second instead of bytes per second.

-t
    Display timestamp for each report.

-V
    Display version information and exit.

delay
    Delay in seconds between each report. If no delay is specified, the command will run once and exit.

count
    Number of reports to generate. If no count is specified, the command will run indefinitely.

The `cifsiostat` command reports Input/Output (I/O) statistics for CIFS (Common Internet File System) clients. It gathers information about network traffic to and from CIFS/SMB servers, providing insights into network performance and potential bottlenecks related to file sharing. Unlike `iostat` which reports disk I/O, `cifsiostat` focuses on the network I/O performance of CIFS clients. It displays metrics such as reads, writes, bytes transferred, average request size, and time spent in I/O operations. The command relies on information exposed by the kernel via the CIFS driver's statistics interface. It's useful for diagnosing network slowness when accessing shared files, monitoring the load on CIFS servers, and identifying potential areas for network optimization. It provides a real-time view of CIFS I/O activities which helps system administrators troubleshoot and manage network file sharing performance effectively.

Requires the CIFS driver to be loaded and properly configured to expose the necessary statistics. The specific statistics available may vary depending on the kernel version and CIFS client implementation. The command measures network I/O from the client's perspective, not the server's. The server side I/O performance can be observed via iostat and related tools.

The command output typically includes the following fields:

CIFS: CIFS client mount point.
rMB/s: Read megabytes per second.
wMB/s: Write megabytes per second.
rops/s: Read operations per second.
wops/s: Write operations per second.
rsize: Average read size in bytes.
wsize: Average write size in bytes.
avgqu-sz: Average queue length.
await: Average time (in milliseconds) for I/O requests issued to the network to be served. This includes the time spent by the requests in queue and the time spent servicing them.
rawait: Average time (in milliseconds) for read requests issued to the network to be served. This includes the time spent by the requests in queue and the time spent servicing them.
wawait: Average time (in milliseconds) for write requests issued to the network to be served. This includes the time spent by the requests in queue and the time spent servicing them.

The `cifsiostat` command was developed as part of system performance monitoring tools, designed specifically to provide insights into CIFS client I/O activity. Its development was motivated by the need to effectively diagnose performance issues in network file sharing environments using the CIFS protocol. It allows administrators to measure and track CIFS I/O statistics, helping them troubleshoot issues like slow file access and network bottlenecks. The command has been maintained and improved along with the Linux kernel and related CIFS/SMB protocol support.

iostat(1), vmstat(8), sar(1)