Ultrabay

IBM UltraBay UltraBay1 is IBM's name for the swapable drive slot. With IBMs words: "The ThinkPad UltraBay, also standard with the system, is an intelligent bay that switches its pinout signals to allow the installation of standard and optional features in what would normally be just the FDD bay." Introduced back in the times of the 750 ThinkPads, this technology has gone through redesigns with almost every new generation of ThinkPad models, possibly leading to some confusion that is hopefully cleared up here. The following table gives an overview of the different UltraBay types, in which models they occurred and what drives are available for them. Note that the optical drive bay in G series ThinkPads is not an UltraBay in that the drives are fixed and not removable. On the media side different UltraBays relate to the form factor of the drives they accept, e.g early A, T and X series models can accept UltraBay devices up to 12.5mm in thickness, whereas current T and X series machines are limited to devices no more than 9.5mm thick.

Overview over UltraBay types and available devices

UltraBay Type	featured in	available drives (see UltraBay Devices for details)
UltraBay	355, 355C, 355CS, 360, 360C, 360CS, 360P, 360CE, 360CSE, 360PE, 370C, 750, 750C, 750CS, 750P, 755C, 755CE, 755CS, 755CSE, 755CV, 755CX, 760C, 760L, 760E	, 2.88 MB diskette, PCMCIA Cartridge, IBM Wireless Modem ARDIS, IBM Wireless Modem
UltraBay Thick	755CD, 755CDV, 760CD, 760E, 760ED, 760EL, 760ELD, 760LD, 760XD, 760XL, 765D, 765L, SelectaDock I, SelectaDock II	, 2.88 MB diskette, PCMCIA Cartridge, IBM Wireless Modem ARDIS, IBM Wireless Modem
UltraBay II	770, 770E, 770ED, 770X, 770Z, SelectaDock III
UltraBay FX	390, 390E, 390X, i Series 1720, i Series 1721
UltraslimBay	600, 600E, 600X, UltraBase, Portable Drive Bay
UltraBay 2000	A20m, A20p, A21e, A21m, A21p, A22e, A22m, A22p, A30, T20, T21, T22, T23, Dock, Dock II, UltraBase X2, Portable Drive Bay 2000
UltraBay Plus	A30, A30p, A31, A31p, R30, R31, R32, R40, T23, T30, UltraBase X3	, WorkPad Cradle, Numpad
UltraBay Slim	T40, T40p, T41, T41p, T42, T42p, T43, T43p, T60, T60p, Z60t, UltraBase X4, UltraBase X6, ThinkPad X4 Dock	, Serial/Parallel Port Adapter
UltraBay Enhanced	R50, R50p, R51, R52, Z60m ThinkPad Advanced Dock

Compatibility Matrix (read columns as slots with rows as devices that are compatible)

Slots Devices	UltraBay	UltraBay Thick	UltraBay II	UltraBay FX	UltraslimBay	UltraBay 2000	UltraBay Plus	UltraBay Slim	UltraBay Enhanced
UltraBay	yes	yes	Adapter	-	-	-	-	-	-
UltraBay Thick	-	yes	Adapter	-	-	-	-	-	-
UltraBay II	-	-	yes	-	-	-	-	-	-
UltraBay FX	-	-	-	yes	-	-	-	-	-
UltraslimBay	-	-	-	-	yes	-	-	-	-
UltraBay 2000	-	-	-	-	-	yes	yes	-	-
UltraBay Plus	-	-	-	-	-	-	yes	-	-
UltraBay Slim	-	-	-	-	-	Adapter	Adapter	yes	yes
UltraBay Enhanced	-	-	-	-	-	Adapter	Adapter	-	yes

Characteristics

• UltraBay: no hot swapping
• UltraBay Thick: Thicker version of UltraBay to support CD-ROM drive
• UltraBay II: supports hot swapping, blending has cut out edge on the right
• UltraBay FX: the combined Floppy drive and CD-ROM, DVD or CDRW mechanism found in the 390/390E/390X
• UltraSlimBay: supports hot swapping; Frame, rectangle like blending
• UltraBay 2000: supports hot swapping; Frame, blending has cut out egde on the right
• UltraBay Plus: same as UltraBay 2000, but can take the UltraBay Plus Device Carrier which in turn can hold the UltraBay Plus c500 Cradle or the UltraBay Plus Numeric Keypad
• UltraBay Slim: supports hot swapping; notably thinner than UltraBay 2000, cut out right edge in blending
• UltraBay Enhanced: supports hot swapping; slightly thicker than UltraBay Slim, but accepts UltraBay Slim devices

Linux Support

The pinout switching is done by the BIOS and hardware, so that it is completely transparent to the operating system.

• Floppy drives are supported by the standard floppy driver.
• ZIP drive support is possible through the ide-disk driver.
• IDE hard disks and optical drives are supported by the IDE or ata_piix driver in the linux kernel. SCSI emulation via ide-scsi is possible.
• Batteries are automatically handled by the hardware, but can be controlled further by using tp_smapi.
• UltraBay Plus devices should be handled by the USB subsystem, but if the actual devices are is not known.

Hotswapping

Hotswap when using the ide-disk driver

The following applies if you use the ide-disk driver for the UltraBay device.

Hotswapping is supposed to be supported as well, using either hdparm/Debian hotswap or lt_hotswap to (un)register IDE devices. The latter is the recommended method with kernels from 2.6, since it will leave DMA working. However, for recent models (R52, T43, X41, Z60 and later) no method is known to work while maintaining DMA support; see Problems with SATA and Linux.

Only IDE devices (HDD's, optical drives, zip drives) require special treatment - batteries, floppies and other devices can just be pulled from the bay, provided they are not mounted or in use at the time. However, you should still power them down first using the ibm-acpi eject function.

The ibm-acpi kernel module has an eject function (# echo eject > /proc/acpi/ibm/bay). This only manages the ACPI calls to power down the device and the bay. It does not actually unregister the device from the IDE driver. # cat /proc/acpi/ibm/bay shows "unoccupied" unless an IDE device is present, but the eject function still works and should still be used.

To unregister the device, you can either use the Debian hotswap package, or lt_hotswap.

Debian hotswap also allows the drive to be swapped as a normal user by default, which is useful. You should use hotswap to unregister the device and then # echo eject > /proc/acpi/ibm/bay. However, if you use this method on a 2.6 kernel, you will loose DMA support for the reinserted drive. This is due to kernel issues. This method was reported to work on a ThinkPad T23 (kernels 2.6.8.1, 2.6.14.2 and 2.6.15-arch) and T42 (kernel 2.6.13), but fails on a ThinkPad T43 (kernel 2.6.14.3).

lt_hotswap is now the recommended method to un- and reregister the IDE device. It installs as a kernel module and has support for automatically unregistering the device when the eject event is generated by ibm-acpi. It will leave DMA support intact. It has supported to work on a ThinkPad T22 and T40 and should work with many other models (but not recent models which require the ata_piix driver for disk DMA support).

Hotswap when using the ata_piix driver

Recent ThinkPad model use an Intel ICH6M controller which requires use of the ata_piix driver for full functionality (e.g., DMA support); see also Problems with SATA and Linux.

You can safely disable the drive by issuing the following:

# echo 1 > /sys/class/scsi_device/1\:0\:0\:0/device/delete
# echo eject >  /proc/acpi/ibm/bay

The drive can now be ejected.

Mainline kernels cannot yet reliably recognize newly (re-)inserted UltraBay drives without a reboot. Once support is added, it can be invoked by issuing the following after inserting an UltraBay drive:

# echo 0 0 0 >  /sys/class/scsi_host/host1/scan

See this thread for an experimental kernel that adds hotplug support.

External Sources

• IBMs page on using a second hard drive adapter in the Ultrabay 2000 slot under Linux

FOOTNOTES [Δ]

1. IBM originally used the spelling UltraBay with a capital B and later switched to Ultrabay with a lower b. We are sticking with the capital B here.