usbms Special File

Purpose

Provides access to the Universal Serial Bus (USB) Mass Storage Client device driver.

Description

The usbms special file provides block and character (raw) access to USB Bulk Mass Storage devices similar to Removable Disk EXchange (RDX), flash drives, and disk devices.

The r prefix on a special file name means that the drive is accessed as a raw device rather than a block device. The performance of all data transfers in multiples of the logical block length of the disk is required for performing raw I/O operation on a RDX, flash drive, and disk drive devices. Also, all the lseek subroutines made to the raw USB Mass storage device must set the file offset pointer to a value that is a multiple of the specified logical block size.

USB Mass Storage Bulk Flash or RDX Devices

The special files /dev/usbms0 and /dev/usbms1,... provide block access to USB Mass Storage Bulk Flash or RDX devices. The special file /dev/rusbms0, /dev/rusbms1,... provide character access.

When a RDX cartridge is ejected from the drive for a mounted CD-ROM or UDFS file system, the files on the cartridge cannot be accessed. Before these files can be accessed again, the file systems mounted from the cartridge must be unmounted. Processes that have open files on these file systems must be exited. Processes that have current directories on these file systems must be moved. If these actions do not work, perform a force unmount.

The man command can become unresponsive if you eject the RDX cartridge from a mounted CD-ROM or UDFS file system. Reinserting the cartridge disc does not fix the problem. All processes (graphical and ASCII) must be exited and the file system must be force unmounted and mounted again. The man commands can then be started again.

The description of the USB mass storage client device driver in the AIX® Version 7.1 Technical Reference: Kernel and Subsystems, Volume 1 provides the implementation specifications for the USB Mass Storage Client Device Driver.