USBDISK(4) USBDISK(4)
NAME
usbdisk, usbfat: - serve USB mass storage devices
SYNOPSIS
usb/disk [ -dDfl ] [ -m mountpoint ] [ -s srvname ] [ ctrlno
id ]
usbfat: [ -fl ] [ disk [ mntpt ] ]
DESCRIPTION
Disk serves a directory named mountpoint (default /n/disk)
containing the files ctl and n, where n is the number of a
LUN to access, for all detected LUNs of the named or found
USB device. Disk searches for a USB device with class 8
(storage), subclass 2 (ATAPI CD/DVD/BD), 5 (removable,
ATAPI-like) or 6 (SCSI transparent), and protocol 0x50
(bulk), or uses /dev/usb/ctrlno/id if specified. In every
LUN directory are the files data and raw. data gives
read/write access to blocks of the device. raw is a raw
SCSI-like interface (talk to it with scuzz(8)).
The root directory's ctl file accepts the command `reset',
which tells disk to again fetch the information about all
LUNs, and yields the device geometries when read.
The -d option generates debugging output. The -f option
avoids freaking out some cheap USB flash disks by not issu-
ing UMS reset commands to them. The -l option asks the
device for its maximum LUN. By default, disk assumes a max-
imum LUN of zero, since some devices get upset if you ask
them for their maximum LUN. Flash memory devices are likely
to have multiple LUNs. The -m option mounts the served
hierarchy on mountpoint instead of /n/disk. The -s option
posts a mountable file descriptor as /srv/srvname. The -D
option prints all 9P messages.
EXAMPLES
Access the usual preformatted FAT partition:
% usb/usbd
% usb/disk -l
% disk/fdisk -p /n/disk/0/data
part dos 7 31559
% dossrv -f /n/disk/0/data:7 usbstorage
dossrv: serving #s/usbstorage
% mount /srv/usbstorage /n/d:
% ls -l /n/d:
alrw-rw-rw- M 39 bill trog 180364 Oct 5 18:14 /n/d:/9LOAD
d-rwxrwxrwx M 39 bill trog 0 Nov 13 14:30 /n/d:/benedict
USBDISK(4) USBDISK(4)
The latter part of the above example, from disk/fdisk to
mount, has been packaged up as usbfat:, which mounts the FAT
file system in the DOS partition of the named disk (by
default /n/disk/0/data) on mntpt (by default /n/usb).
FILES
/n/disk default mountpoint
/n/usb default mountpoint for FAT file system
on the disk
/srv/usbfat.$user FAT file system service
SOURCE
/sys/src/cmd/usb/disk
/rc/bin/usbfat:
SEE ALSO
fs(3), sd(3), usb(3), partfs(8), prep(8), scuzz(8)
BUGS
Should implement sd(3)'s interface for each LUN. Currently,
if there are multiple partitions, you can use fs(3) to man-
age them. If `fdisk -p' prints nothing, there is no parti-
tion table on the device, so one can invoke dossrv(4)
directly.
USB 1 flash disks' I/O rates are slow and variable. Reading
and writing in large units (e.g., 4KB) seems to be faster by
an order of magnitude when transferring large volumes of
data.