===== Common Access Method (CAM) Storage Subsystem =====

CAM is the **C**ommon **A**ccess **M**ethod storage subsystem in %%FreeBSD%%, providing a uniform and modular method implementing drivers to control various SCSI ATA, NVMe, and MMC/SD storage devices.

===== Documentation =====

  * [[https://man.freebsd.org/cam(4)|FreeBSD cam(4) manual page]]
  * [[https://man.freebsd.org/camcontrol(8)|camcontrol(8): CAM control program]]
  * [[https://docs.freebsd.org/en/books/arch-handbook/scsi/|FreeBSD Architecture Handbook: Chapter 12. Common Access Method SCSI Controllers]]

===== More Information =====

  * [[https://uditagarwal.in/understanding-freebsds-cam-framework/|Understanding FreeBSD’s CAM Framework]] (Udit Kumar Agarwal, 2018)
  * [[https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf|I/O Scheduling in FreeBSD's CAM Subsystem (PDF)]] (WarnerLosh)

===== Historical Page Notes =====

List of things desired for CAM:

  * Provide a means of specifying a cam_path filter for xpt_register_async() and still get the initial broadcast of related events that occurs if the path is not specified today, with the filter applied.
  * Modify cam_ed so that transport-specific parts are in an union instead of alongside each other.  Might be best to move those structures into transport-specific headers too.