UMASS(4) BSD Kernel Interfaces Manual UMASS(4)


umass — USB Mass Storage Devices driver


To compile this driver into the kernel, place the following line in your kernel configuration file:

device scbus
device usb
device umass

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):



The umass driver provides support for Mass Storage devices that attach to the USB port.

To use the umass driver, usb(4) and one of uhci(4) or ohci(4) or ehci(4) or xhci(4) must be configured in the kernel. Additionally, since umass uses the SCSI subsystem and sometimes acts as a SCSI device, it requires da(4) and scbus(4) to be included in the kernel.


The umass driver supports USB Mass Storage devices, including:

ADTEC Stick Drive AD-UST32M, 64M, 128M, 256M

Denno FireWire/USB2 Removable 2.5-inch HDD Case MIFU-25CB20

FujiFilm Zip USB Drive ZDR100 USB A

GREEN HOUSE USB Flash Memory "PicoDrive" GH-UFD32M, 64M, 128M

Huawei Mobile (SD slot)

IBM 32MB USB Memory Key (P/N 22P5296)

IBM 256MB USB Drive (MSYSTEM DiskOnKey2)

IBM ThinkPad USB Portable CD-ROM Drive (P/N 33L5151)


I-O DATA USB x6 CD-RW Drive CDRW-i64/USB (CDROM only)

I-O DATA USB/IEEE1394 Portable HD Drive HDP-i30P/CI, HDP-i40P/CI

Iomega USB Zip 100/250 drive

Iomega Zip750 USB2.0 drive

Keian USB1.1/2.0 3.5-inch HDD Case KU350A

Kurouto Shikou USB 2.5-inch HDD Case GAWAP2.5PS-USB2.0

LaCie P3 HardDrive USB 200GB

Logitec LDR-H443U2 DVD-RAM/-R/+R/-RW/+RW drive

Logitec Mobile USB Memory LMC-256UD

Logitec USB1.1/2.0 HDD Unit SHD-E60U2

Logitec USB Double-Speed Floppy Drive LFD-31U2

Logitec USB/IEEE1394 DVD-RAM/R/RW Unit LDR-N21FU2 (CDROM only)

MELCO USB Flash Disk "ClipDrive", RUF-C32M, -C64M, -C128M, -C256M, -C512M

MELCO USB Flash Disk "PetitDrive", RUF-32M, -64M, -128M, -256Mm

MELCO USB2.0 Flash Disk "PetitDrive2", RUF-256M/U2, -512M/U2

MELCO USB2.0 MO Drive MO-CH640U2

Matshita CF-VFDU03 floppy drive

Merlin SM300 MP3/WMA Player (256Mb)

Microtech International, Inc. USB-SCSI-HD 50 USB to SCSI cable

Motorola E398 Mobile Phone (TransFlash memory card)

NOVAC USB2.0 2.5/3.5-inch HDD Case NV-HD351U

PNY Attache Flash Drive

Panasonic ("Matshita FDD CF-VFDU03")

Panasonic KXL-CB20AN Portable DVD-ROM/CD-R/RW

Panasonic KXL-CB35AN (DVD-ROM & CD-R/RW)

Panasonic USB2.0 Portable CD-RW Drive KXL-RW40AN (CDROM only)

Panasonic floppy drive

Qware BeatZkey! Pro

RATOC Systems USB2.0 Removable HDD Case U2-MDK1, U2-MDK1B

SanDisk SDDR-31 (Compact Flash)

SanDisk SDDR-75 (only Compact Flash port works)

Sitecom CN-300 MultiFlash (MMC/SD, SmartMedia, CF, MemoryStick)

Sony Portable CD-R/RW Drive CRX10U (CDROM only)

TEAC Portable USB CD-ROM Unit CD-110PU/210PU

Time DPA20B MP3 Player (1Gb)

Trek Thumbdrive 8MB

VAIO floppy drive (includes Y-E Data Flashbuster-U)

Y-E Data floppy drive (720/1.44/2.88Mb)

Among the supported digital cameras are:

Asahi Optical (PENTAX) Optio 230 & 330


device umass
device scbus
device da
device pass

Add the umass driver to the kernel.

camcontrol rescan 0

Rescan a Zip drive that was added after boot. The command above assumes that the Zip drive is on the first SCSI bus in the system.

camcontrol rescan 0:0:0
camcontrol rescan 0:0:1
camcontrol rescan 0:0:2
camcontrol rescan 0:0:3

Rescan all slots on a multi-slot flash reader, where the slots map to separate LUNs on a single SCSI ID. Typically only the first slot will be enabled at boot time. Again, this assumes that the flash reader is the first SCSI bus in the system.

bsdlabel -w da0 zip100
newfs da0c
mount -t ufs /dev/da0c /mnt

Write a disklabel to the Zip drive (see vpo(4) for the disktab(5) entry), creates the file system and mounts the new file system on /mnt.

newfs_msdos /dev/da0

Create a new FAT type file system. Care should be taken not to run newfs(8) on devices that already contain data, as this will result in the information being lost.

Many consumer devices such as digital cameras automatically create MS-DOS based file systems when storing information such as images and videos. These file systems can be accessed by specifying the file system type as msdosfs when using mount(8).


cfumass(4), ehci(4), ohci(4), uhci(4), usb(4), vpo(4), xhci(4), disktab(5), bsdlabel(8), camcontrol(8)


The umass driver was written by MAEKAWA Masahide <bishop [AT]> and Nick Hibma <n_hibma [AT]>.

This manual page was written by Nick Hibma <n_hibma [AT]>.

BSD April 19, 2014 BSD