---
name: "ch"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["linux", "freebsd", "openbsd"]
url: "https://new.carta.tech/ch"
---

# ch(4)

SCSI media-changer (juke box) driver

## NAME

**ch** – SCSI media-changer (juke box) driver

## SYNOPSIS

**ch? at scsibus?**

## DESCRIPTION

The **ch** driver provides support for SCSI juke boxes. It allows many slots of media to be multiplexed between a number of drives.

A SCSI adapter and a logical scsibus must also be separately configured into the system before a SCSI changer can be configured.

As the SCSI adapter is probed during boot, the SCSI bus is scanned for devices. Any devices found which answer as "Changer" type devices will be “attached” to the **ch** driver. The first device found will be attached as *ch0* and the next *ch1*, etc. It is also possible to specify what **ch** unit a device should come on-line as; refer to [scsi(4)](/scsi/4.md) for details on kernel configuration.

## FILES

- */dev/ch\[0-9\]*

  device entries

## SEE ALSO

[chio(1)](/chio/1.md), [cd(4)](/cd/4.md), [intro(4)](/intro/4.md), [scsi(4)](/scsi/4.md), [sd(4)](/sd/4.md), [st(4)](/st/4.md)

## HISTORY

The **ch** driver appeared in 386BSD 0.1.