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Newsgroups: comp.os.linux.announce,comp.os.linux.admin
From: Drew Eckhardt <drew@kinglear.cs.Colorado.EDU>
Subject: Linux SCSI HOWTO
Keywords: Linux SCSI drive tape CD-ROM HOWTO
Organization: University of Colorado at Boulder
Approved: linux-announce@tc.cornell.edu (Matt Welsh)
Linux SCSI HOWTO by Drew Eckhardt (drew@cs.colorado.edu)
last updated September 14, 1993
This HOWTO covers the Linux SCSI subsystem, as implemented in Linux
kernel revision .99.13 and alpha code available as of September 19, 1993.
For additional information, you may wish to join the SCSI channel of the
Linux activists list - mail to linux-activists-request@joker.cs.hut.fi
with the line
X-MN-Admin: join SCSI
in the header.
I'm aware that this document isn't the most user-friendly, if
you have constructive comments on how to rectify the situation
you're free to mail me about it.
Table of contents
Section 1 Common Problems
Section 2 Reporting Bugs
Section 3 Hosts
Subsection A Supported and Unsupported Hardware
Subsection B Common Problems
Subsection C Adaptec 151x, 152x (ALFALFA diffs)
Subsection D Adaptec 154x (Standard)
Subsection E Adaptec 174x (Standard))
Subsection F Allways IN2000 (ALPHA)
Subsection G Future Domain 16x0 with TMC-1800 or
TMC-18C50 chip (Standard)
Subsection H Generic NCR5380 (ALFALFA diffs)
Subsection I Seagate ST0x/Future Domain TMC-8xx/TMC-9xx
(Standard)
Subsection J Trantor T128/T128F/T228 (ALFALFA diffs)
Subsection K Ultrastor 14f, 34f (Standard)
Subsection L Ultrastor 14f, 24f, 34f (ALFALFA diffs)
Subsection M Western Digital 7000 (Standard)
Section 4 Disks
Subsection A Supported and Unsupported Hardware
Subsection B Common Problems
Subsection C Device Files
Subsection D Disk Geometry
Subsection E Partitioning
Section 5 CD ROMs
Subsection A Supported and Unsupported Hardware
Subsection B Common Problems
Subsection C Device Files
Section 6 Tapes
Subsection A Supported and Unsupported Hardware
Subsection B Common Problems
Subsection C Device Files
Section 7 Generic
Subsection A Supported and Unsupported Hardware
Subsection B Common Problems
Subsection C Device Files
Section 1 : Common Problems
1. A SCSI device shows up at all possible IDs
If this is the case, you've strapped the device at the same
address as the controller (typically, 7, although some boards
use other addresses). Please change the jumper settings.
2. You get sense errors when you know the devices are error free
Sometimes this is caused by bad cables or impropper termination.
Your SCSI bus must be terminated at both ends (using external
terminators, or onboard terminators on the host adapter or
devices) and not in the middle.
3. A kernel configured with networking does not work.
The auto-probe routines for many of the network drivers
are not passive, and will interfere with operation with some
of the SCSI drivers.
Section 2 : Reporting Bugs
The Linux SCSI developers don't necessarily maintain old revisions
of the code due to space constraints. So, if you are not running the
latest publically released Linux kernel (note that many of the Linux
distributions, such as MCC, SLS, Yggdrasil, etc. often lag one or more
revisions behind this) chances are we will be unable to solve your
problem. So, before reporting a bug, please check to see if it exists
with the latest publically available kernel.
If after upgrading, and reading this document thoroughly, you still
believe that you have a bug, please mail a bug report to the SCSI channel
of the mailing list where it will be seen by many of the people who've
contributed to the Linux SCSI drivers.
In your bug report, please provide as much information as possible
regarding your hardware configuration, and all of the messages that
Linux prints when it boots. Your chances of getting the bug fixed increase
exponentially with the amount of information provided.
The bottom line is that if we can't reproduce your bug, and you can't
point at us what's broken, it won't get fixed.
Section 3 : Hosts
Subsection A : Supported and Unsupported Hardware
Drivers in the distribution kernel :
Adaptec 154x (including clones from Bustek and DTC - DTC models that
work are the 3290 and 3292), Adaptec 174x, Future Domain 850, 885, 950,
and other boards in that series (but not the 880 board unless you make
the appropriate patch), Future Domain 16x0 with TMC-1800 or TMC-18C50 chip,
Seagate ST0x, Ultrastor 14F and 34F, and Western Digital 7000
Drivers included in ALFALFA diffs :
Adaptec 1520, Ultrastor 14F, 24F, 34F, Trantor T128/T128F/T228
ALFALFA diffs are available from tsx-11.mit.edu:/pub/linux/ALPHA/scsi
0.99.13.scsipatch.txt
A bootable kernel incorporating the ALFALFA disks is
0.99.13.scsipatch.zImage
Alpha drivers :
Allways IN2000
Drivers that are being developed, but aren't publically available
PAS-16 (based on my NCR5380 driver, works if booted with a CD in
the drive but fails if none is there or there is a disk change)
Richoch NCR5380 (based on my NCR5380 driver, works but gives low
(ie 50K/sec) performance since DMA transfers are not used
yet)
NCR539x (The main motivation for this is that the R4000 based
MIPS boards will be using a NCR53cf9x of some flavor. However,
since the hardware isn't here yet, the driver is in no hurry)_
SCSI Hosts that would work with a little work :
Trantor T130 - using the NCR5380 driver (different chip, 5380
ASIC cell used)
SCSI Hosts that will not work :
Adaptec 2742, 2742T, non Adaptec compatable DTC boards (including the 3270
and 3280), Mylex, all parallel->SCSI adapters, Rancho SCSI boards,
Grass Roots SCSI boards.
If you want to run Linux on an unsupported piece of hardware, your
options are to either write a driver yourself (Eric Youngdale and I are
usually willing to answer technical questions concerning the Linux
SCSI drivers) or to commision a driver.
Subsection B : Common Problems
1. SCSI timeouts
Make sure interrupts are enabled correctly, and there are no
IRQ, DMA, or address conflicts with other boards.
2. Boards using the BIOS to autoprobe are not detected (see the
Autoprobe entry for your host adapter)
This fails if the BIOS is disabled (see the Autoprobe Override
entry for your board to see if you can override it) or your
boards "signature" doesn't match one of the known ones.
If the BIOS is installed, please use DOS and DEBUG to
find a signature that will detect your board -
Ie, if your board lives at 0xc8000, under DOS do
debug
d c800:0
q
and send a message to the SCSI channel of the mailing list with
the ASCII message, with the length and offset from the base
address (ie, 0xc8000). Note that the EXACT text is required.
3. Boards using memory mapped IO do not work.
This is often caused when the memory mapped I/O ports
are incorrectly cached. You should have the board's
address space marked as uncachable in the XCMOS settings.
If this is not possible, you will have to disable cache
entirely.
4. The bootable kernel for an ALPHA driver does not work,
resulting in a "kernel panic : cannot mount root device"
message, or it does not work with your Linux distribution.
You'll need to edit the binary image of the kernel (before
or after writing it out to disk), and modify a few two byte
fields (little endian) to gurantee that it will work on your
system.
1. default swap device at offset 502, this should be set to 0
2. ram disk size at offset 504, this should be set to the size
of the boot floppy in K - ie, 5.25" = 1200, 3.5" = 1440.
This means the bytes are
3.5" : 0xA0 0x05
5.25" : 0xB0 0x04
3. root device offset at 508, this should be 0, ie the boot
device.
dd or rawrite the file to a disk. Insert the disk in the
first floppy drive, wait until it prompts you to insert
the root disk, and insert the root floppy from your
distribution.
5. Installing a device driver not bundled with the distribution kernel
You need to start with the version of the kernel used by the
driver author. This revision may be alluded to in the documentation
included with the driver.
Various recent kernel revisions can be found at
nic.funet.fi:/pub/OS/Linux/PEOPLE/Linus
as linux-version.tar.gz
They are also mirrored at tsx-11.mit.edu and various other sites.
cd to /usr/src.
Remove your old Linux sources, if you want to keep a backup copy
of them
mv linux linux-old
or whatever.
Untar the archive
gunzip < linux-0.99.12.tar.gz | tar xvfp -
Apply the patches. The patches will be relative to some directory
in the filesystem. By examining the output file lines in the patch
file (grep for ^---), you can tell where this is - ie patches with
these lines
--- ./kernel/blk_drv/scsi/Makefile
--- ./config.in Wed Sep 1 16:19:33 1993
would have the files relative to /usr/src/linux.
Untar the driver sources at an appropriate place - you
can do a
tar tfv patches.tar
or whatever to get a listing, and move files as necessary
(The SCSI driver files should live in /usr/src/linux/kernel/blk_drv/
scsi)
Either cd to the directory they are relative to and do a
patch -p0 < patch_file
or tell patch to "strip off" leading paths components. Ie,
if the files started with
--- linux-new/kernel/blk_drv/scsi/Makefile
and you wanted to apply them while in /usr/src/linux, you
could cd to /usr/src/linux and do a
patch -p1 < patches
to strip off the "linux-new" component.
After you have applied the patches, look for any patch rejects,
which will be the name of the rejected file with a # suffix appended.
Ie
find /usr/src/linux/ -name "*#" -print
If any of these exist, look at them. In some cases, the
differences will be in RCS identifiers and will be harmless,
in other cases, you'll have to manually apply important
parts. Documentation on diffs files and patch is beyond the
scope of this document.
Next, cd to /usr/src/linux and do a
make config
to choose the options you want
If you are installing off of floppy disk, you'll also have to
edit the Makefile to set the ROOT device to ramdisk.
do a make depend
followed by
make
You should end up with a file "zImage". Write this out to a floppy
disk -
cat zImage > /dev/fd0
and use that to boot your system. When it comes up, it should prompt
for the root floppy, use a1 from SLS or whatever and you'll be fine.
Subsection C : Adaptec 151x, 152x (ALFALFA diffs)
ALFALFA diffs are available from tsx-11.mit.edu:/pub/linux/ALPHA/scsi
0.99.13.scsipatch.txt
A bootable kernel incorporating the ALFALFA disks is
0.99.13.scsipatch.zImage
Supported Configurations :
Addresses : 0xd8000, 0xdc000, 0xd0000, 0xd4000, 0xc8000, 0xcc000, 0xe0000,
0xe4000.
Ports : 0x140, 0x340
IRQs : 9, 10, 11, 12
DMA is not used
IO : port mapped
Autoprobe : works with all supported configurations, requires installed BIOS
Autoprobe Override :
Compile time :
Define PORTBASE, IRQ, SCSI_ID, RECONNECT as appropriate, see Defines
LILO commandline : aha152x=<PORTBASE>,<IRQ>,<SCSI-ID>,<RECONNECT>
Defines :
AUTOCONF : use configuration the controller reports (only 152x)
IRQ : override interrupt channel (9,10,11 or 12) (default 11)
SCSI_ID : override scsiid of AIC-6260 (0-7) (default 7)
RECONNECT : override target dis-/reconnection/multiple
outstanding command - set to non-zero to enable, zero to
disable.
DONT_SNARF : Don't register ports (pl12 and below)
SKIP_BIOSTEST : Don't test for BIOS signature (AHA-1510 or disabled BIOS)
PORTBASE : Force port base. Don't try to probe
Subsection D : Adaptec 154x
Supported Configurations :
Ports : 0x330 and 0x334
IRQs : 9, 10, 11, 12, 14, 15
DMA channels : 5, 6, 7
IO : port mapped, bus master
Unsupported Configurations:
The 'C' revision BIOS options to
- Autoprobe
- Support > 2 hard disks with the BIOS
- Do extended mapping
Autoprobe : works with all supported configurations, does not
require an installed BIOS.
Autoprobe override : none
Antiquity Problems, fix by upgrading :
1. Linux kernel revisions prior to .99.10 don't support the 'C'
revision.
Common problems :
1. There are unexpected errors with a revision C board.
Early examples of the 154xC boards have a high slew rate on
one of the SCSI signals, which results in signal reflections
when cables with the wrong impedance are used.
Try changing the cables, ESPECIALLY if you are using
external cables.
2. There are error messages (ie, interrupt received, no mail) during
initialization with the C revision boards.
These may result from the use of one of the unsupported BIOS
options. Turn it off.
Subsection E : Adaptec 174x
Supported Configurations :
Slots : 1-8
Ports : EISA board, not applicable
IRQs : 9, 10, 11, 12, 14, 15
DMA Channels : EISA board, not applicable
IO : port mapped, bus master
Autoprobe : works with all supported configurations
Autoprobe override : none
Common Problems :
1. If the Adaptec 1740 driver prints the message
"aha1740: Board detected, but EBCNTRL = %x, so disabled it."
your board was disabled because it was not running in enhanced
mode. Boards running in standard 1542 mode are not supported.
Subsection F : Allways IN2000
ALPHA available via ftp tsx-11.mit.edu/pub/linux/ALPHA/SCSI/in2000
driver is in2000.tar.z, bootable kernel zImage
Ports : 0x100, 0x110, 0x200, 0x220
IRQs : 10, 11, 14, 15
DMA is not used
IO : port mapped
Autoprobe : BIOS not required
Autoprobe override : none
Common Problems :
1. There are known problems in systems with IDE drives and with
swapping.
Subsection G : Future Domain 16x0 with TMC-1800 or TMC-18C50 chip
Supported Configurations :
BIOSs : 2.0, 3.0, 3.2
BIOS Addresses : 0xc8000, 0xca000, 0xce000, 0xde000
Ports : 0x140, 0x150, 0x160, 0x170
IRQs : 3, 5, 10, 11, 12, 14, 15
DMA is not used
IO : port mapped
Autoprobe : works with all supported configurations, requires
installed BIOS
Autoprobe Override : none
Antiquity Problems, fix by upgrading :
1. Old versions do not support the TMC-18C50 chip, and will fail with
newer boards.
2. Old versions will not have the most current BIOS signatures for
autodetection.
Subsection H : Generic NCR5380 (ALFALFA diffs)
ALFALFA diffs are available from tsx-11.mit.edu:/pub/linux/ALPHA/scsi
0.99.13.scsipatch.txt
A bootable kernel incorporating the ALFALFA disks is
0.99.13.scsipatch.zImage
Supported and Unsupported Configurations :
Ports : all
IRQs : all
DMA channels - DMA is not used
IO : port mapped
Autoprobe : none
Autoprobe Override :
Compile time : Define GENERIC_NCR5380_OVERRIDE to be an array of tupples
with port, irq - ie
#define GENERIC_NCR5380_OVERRIDE {{0x330, 5,}}
for a board at port 330, IRQ 5.
The symbolic IRQs IRQ_NONE and IRQ_AUTO may be used.
LILO command line : ncr5380=port,irq
255 may be used for no irq, 254 for irq autoprobe.
Notes : the generic driver doesn't support DMA yet, and pseudo-DMA
isn't supported in the generic driver.
Subsection I : Seagate ST0x/Future Domain TMC-8xx/TMC-9xx
Supported and Unsupported Configurations :
Base addresses : 0xc8000, 0xca000, 0xcc000, 0xce000, 0xdc000, 0xde000
IRQs : 3, 5
DMA channels : DMA is not used
IO : memory mapped
Autoprobe : probes for address only, IRQ is assumed to be 5,
requires installed BIOS.
Autoprobe Override :
Compile time : Define OVERRIDE to be the base address, CONTROLLER to
FD or SEAGATE as appropriate, and IRQ to the IRQ.
LILO command line : st0x=address,irq or fd8xx=address,irq
Antiquity Problems, fix by upgrading :
1. Versions prior to the one in the Linux .99.12 kernel had a problem
handshaking with some slow devices, where
This is what happens when you write data out to the bus
1. Write byte to data register, data register is asserted to bus
2. time_remaining = 12us
3. wait while time_remaining > 0 and REQ is not asserted
4. if time_remaining > 0, assert ACK
5. wait while time remaining > 0 and REQ is asserted
6. deassert ACK
The problem was encountered in slow devices that do the command
processing as they read the command, where the REQ/ACK handshake
takes over 12us - REQ didn't go false when the driver expected it
to, so the driver ended up sending multiple bytes of data for
each REQ pulse.
2. With Linux .99.12, a bug was introduced when I fixed the arbitration
code, resulting in failed selections on some systems. This was
fixed in .99.13.
Common Problems :
1. There are command timeouts when Linux attempts to read the partition
table or do other disk access.
The board ships with the defaults set up for MSDOS, ie interrupts
are disabled. To jumper the board for interrupts, on the Seagate
use jumper W3 (ST01) or JP3 (ST02) and short pins F-G to select
IRQ 5.
2. The driver can't handle some devices, particularly cheap SCSI
tapes and CDROMs.
The Seagate ties the SCSI bus REQ/ACK handshaking into the PC bus
IO CHANNEL READY and (optionally) 0WS signals. Unfortunately, it
doesn't tell you when the watchdog timer runs out, and you have
no way of knowing for certain that REQ went low, and may end up
seeing one REQ pulse as multiple REQ pulses.
Dealing with this means using a tight loop to look for REQ to
go low, with a timeout incase you don't catch the transition due
to an interrupt, etc. This results in a performance decrease, so it
would be undesireable to apply this to all SCSI devices. Instead,
it is selected on a per-device basis with the "borken" field for
the given SCSI device in the scsi_devices array. If you run into
problems, you should try adding your device to the list of
devices for which borken is not reset to zero (currently,
only the TENEX CDROM drives).
3. A future domain board (most notably the 880) doesn't work.
A few of the Future domain boards use the Seagate
register mapping, and have the MSG and CD bits of the
status register flipped.
You should edit seagate.h, swapping the definitions for
STAT_MSG and STAT_CD, and recompile the kernel with
CONTROLLER defined to SEAGATE and an appropriate
IRQ and OVERRIDE specified.
Defines :
FAST or FAST32 will use blind transfers where possible
ARBITRATE will cause the host adapter to arbitrate for the
bus for better SCSI-II compatability, rather than just
waiting for BUS FREE and then doing its thing. Should
let us do one command per Lun when I integrate my
reorganization changes into the distribution sources.
SLOW_HANDSHAKE will allow compatability with broken devices that don't
handshake fast enough (ie, some CD ROM's) for the Seagate
code.
SLOW_RATE=x, x some number will let you specify a default
transfer rate if handshaking isn't working correctly.
Subsection J : Trantor T128/T128F/T228 (ALFALFA diffs)
ALFALFA diffs are available from tsx-11.mit.edu:/pub/linux/ALPHA/scsi
0.99.13.scsipatch.txt
A bootable kernel incorporating the ALFALFA disks is
0.99.13.scsipatch.zImage
Supported and Unsupported Configurations :
Base addresses : 0xcc000, 00xc8000, 0xdc000, 0xd8000
IRQs : none, 3, 5, 7 (all boards)
10, 12, 14, 15 (T128F only)
DMA is not used.
IO : memory mapped
Autoprobe : works for all supported configurations, requires
installed BIOS.
Autoprobe Override :
Compile time : Define T128_OVERRIDE to be an array of address, irq
tupples. Ie
#define T128_OVERRIDE {{0xcc000, 5}}
for a board at address 0xcc000, IRQ 5.
The symbolic IRQs IRQ_NONE and IRQ_AUTO may be used.
LILO command line : t128=address,irq
-1 may be used for no irq, -2 for irq autoprobe.
Defines :
AUTOSENSE - if defined, REQUEST SENSE will be performed automatically
for commands that return with a CHECK CONDITION status.
PSEUDO_DMA - enables PSEUDO-DMA hardware, should give a 3-4X performance
increase compared to polled I/O.
PARITY - enable parity checking. Not supported
SCSI2 - enable support for SCSI-II tagged queueing. Untested
UNSAFE - leave interrupts enabled during pseudo-DMA transfers. You
only really want to use this if you're having a problem with
dropped characters during high speed communications, and even
then, you're going to be better off twiddling with transfersize.
USLEEP - enable support for devices that don't disconnect. Untested.
Subsection K : Ultrastor 14f, 34f
Supported and Unsupported Configurations :
Ports : 0x130, 0x140, 0x210, 0x230, 0x240, 0x310, 0x330, 0x340
IRQs : 10, 11, 14, 15
DMA channels : 5, 6, 7
IO : port mapped, bus master
Autoprobe : does not work for boards at port 0x310, BIOS not required.
Autoprobe override : compile time only, define PORT_OVERRIDE
Common Problems :
1. The default address for the board, 0x310, is not supported by the
autoprobe code, and may cause conflicts if networking is enabled.
Please use a different address.
2. The networking code probes at some of the addresses, and breaks
the driver. Try a different address, or build a kernel without
networking support.
Subsection L : Ultrastor 14f, 24f, 34f (ALFALFA diffs)
ALFALFA diffs are available from tsx-11.mit.edu:/pub/linux/ALPHA/scsi
0.99.13.scsipatch.txt
A bootable kernel incorporating the ALFALFA disks is
0.99.13.scsipatch.zImage
Ports : 0x130, 0x140, 0x210, 0x230, 0x240, 0x310, 0x330, 0x340
IRQs : 10, 11, 14, 15
DMA channels : 5, 6, 7
IO : port mapped, bus master
Autoprobe : does not work for boards at port 0x310, BIOS not required.
Autoprobe override : compile time only, define PORT_OVERRIDE
Common Problems :
1. The default address for the board, 0x310, is not supported by the
autoprobe code, and may cause conflicts if networking is enabled.
Please use a different address.
Subsection L : Western Digital 7000
Supported Configurations :
BIOS Addresses : 0xce000
Ports : 0x350
IRQs : 15
DMA Channels : 6
IO : port mapped, bus master
Autoprobe : requires installed BIOS
Common Problems :
1. There are several revisisions of the chip and firmware. Supposedly,
revision 3 boards do not work, revision 5 boards do,
chips with no suffix do not work, chips with an 'A' suffix do.
Section 4 : Disks
Subsection A : Supported and Unsupported Hardware
All direct access SCSI devices with a block size of 256, 512, or
1024 bytes should work. Other block sizes will not work.
Removeable media devices, including Bernoulis, flopticals, and MO drives
should work. Other sector sizes will not work.
Subsection B: Common Problems
1. When partitioning, you get a warning message about "cylinder > 1024"
or you are unable to boot from a partition including a logical
cylinder past logical cylinder 1024.
This is a BIOS limitation.
See Subsection D, Disk Geometry, for an explanation.
2. You are unable to partition /dev/hd*
/dev/hd* aren't SCSI devices, /dev/sd* are.
See Subsection C, Device files, and Subsection E, partitioning
for the correct device names and partitioning procedure.
3. Removeable media devices are not recognized at boot time.
Try booting with a disk in the drive.
Subsection C : Device Files
SCSI disks use block device major 8, and there are no "raw" devices
ala BSD.
16 minor numbers are allocated to each SCSI disk, with minor % 16 == 0
being the whole disk, minors 1 <= minor % 16 <= 4 the four primary
partitions, minors 5 <= minor & 16 <= 15 any extended partitions.
Due to constraints imposed by Linux's use of a sixteen bit dev_t with
only eight bits allocated to the minor number, the SCSI disk minor
numbers are assigned dynamically starting with the lowest SCSI HOST/ID/LUN.
Ie, a configuration may work out like this (with one host adapter)
Device Target, Lun SCSI disk
84M Seagate 0 0 /dev/sda
SCSI->SMD bridge disk 0 3 0 /dev/sdb
SCSI->SMD bridge disk 1 3 1 /dev/sdc
Wangtek tape 4 0 none
213M Maxtor 6 0 /dev/sdd
Etc.
The standard naming convention is
/dev/sd{letter} for the entire disk device (minor 0)
/dev/sd{letter}{partition} for the partitions on that device (minor 0 - 15)
Ie
/dev/sda
/dev/sda1
/dev/sda2
/dev/sdb
etc.
Subsection D: Disk Geometry
The problem with partitioning SCSI disks and Linux is that Linux talks
directly to the SCSI interface. Each disk is viewed as the SCSI host
sees it : N blocks, numbered from 0 to N-1, all error free. There is
no portable way to get disk geometry. Conversly, DOS predates
intelligent disks, and requires a head / cylinder / sector mapping.
If you don't care about using DOS, create a translation such that
H * C * S / 2 < size of your drive in megabytes (where a megabyte is
defined as 2^20 bytes).
Otherwise, you'll have to use the BIOS mapping. In some cases, this
will mean reconfiguring the disk so that it is at SCSI ID 0, and
disabling the second IDE drive (if you have one).
You can either use a program like NU, or you can use the following
DEBUG code :
a 0100
mov ah, 8
int 3
g=0100
d
The BIOS imposed limits on the mapped disk geometry are
1 <= # of heads <= 256
1 <= # of cylinders <= 1024
1 <= # of sectors <= 63
So, if you create a partition that includes logical cylinders at or
past logical cylinder 1024, it will be inaccessable to the BIOS and
you will be unable to boot kernels from it. Since Linux uses the
relative sector and length fields in the partition table, and not
the head, cylinder, sector tuples, it is not bound by this restriction
and you will have no problems accessing the partition once Linux is
booted.
You can partition your SCSI disks using the partitioning program
of your choice, under DOS, OS/2, Linux or any other operating
system supporting the standard partitioning scheme.
The correct way to run the Linux fdisk program is by specifying the
device on the command line. Ie, to partition the first SCSI disk,
fdisk /dev/sda
If you don't explicitly specify the device, the partitioning program
may default to /dev/hda, which isn't a SCSI disk.
In some cases, you will get a warning message about a partition ending
past cylinder 1024, see Subsection D, Disk Geometry for an explanation.
Section 5 : CD ROMs
Subsection A: Supported and Unsupported Hardware
SCSI CDs with a block size of 512 or 2048 bytes should work. Other
block sizes will not work.
Subsection B: Common Problems
1. The device is not recognized at boot time.
Try booting with a CDROM in the drive.
2. You can't mount a CDROM
The correct syntax to mount an ISO-9660 CDROM is
mount -t iso9660 /dev/sr0 /mount_point
Note that for this to work, you must have the kernel
configured with support for SCSI, your host adapter,
the SCSI CDROM driver, and the iso9660 filesystem.
Subsection C: Device Files
SCSI CD ROMs use major 11.
Minors are allocated dynamically (See Section 4, Disks, Subsection C,
Device Files for an example) with the first CDROM found being minor 0,
the second minor 1, etc.
The standard naming convention is
/dev/sr{digit} ie
/dev/sr0
/dev/sr1
etc.
Section 6 : Tapes
Subsection A : Supported and Unsupported Hardware
Drives using both fixed and variable length blocks smaller than the
the driver buffer length (set to 32K in the distribution sources) are
supported.
Parameters (block size, buffering, density) are set with ioctls
(usually with the mt program), and remain in effect after the
device is closed and reopened.
Subsection B : Common Problems
1. The tape drive is not recognized at boot time.
Try booting with a tape in the drive.
2. When reading a tape with multiple files, the first tar
is successful, a second tar fails silently, and retrying
the second tar is successful.
User level programs, such as tar, don't understand file marks.
The first tar reads up until the end of the file. The second
tar attempts to read at the file mark, gets nothing, but the
tape spaces over the file mark. The third tar is successful
since the tape is at the start of the next file.
Use mt on the no-rewind device to space forward to the next file.
3. Reading compressed archives fails at the end.
4. Decompressing programs cannot handle the zeros padding the
last block of the file.
To prevent warnings and errors, wrap your compressed files
in a .tar file - ie, rather than doing
tar cfvz /dev/nrst0 file.1 file.2 ...
do
tar cfvz tmp.tar.z file.1 file.2 ...
tar cf /dev/nrst0 tmp.tar.z
5. You can't read a tape made with another operating system or
another operating system can't read a tape written in Linux.
Different systems often use different block sizes. On a
tape device using a fixed blocksize, you will get errors
when reading blocks written using a different block size.
Things that can help you to determine the correct block
size include
- tar defaults to 20 512 byte blocks, ie blocksize = 10k
- Linux prints the blocksize on bootup
Subsection C : Device Files
SCSI tapes use character device major 9.
Due to constraints imposed by Linux's use of a sixteen bit dev_t with
only eight bits allocated to the minor number, the SCSI tape minor
numbers are assigned dynamically starting with the lowest SCSI HOST/ID/LUN.
Rewinding devices are numbered from 0 - with /dev/st0 being c 9 0,
/dev/rst1 c 9 1, etc. Non-rewinding devices have the high bit set -
ie /dev/nrst0 is c 9 128.
The standard naming convention is
/dev/nrst{digit} for non-rewinding devices
/dev/rst{digit} for rewingind devices
Section 7 : Generic
Subsection A : Supported Hardware
The Generic SCSI device driver provides an interface for sending
SCSI commands to all SCSI devices - disks, tapes, CDROMs, media
changer robots, etc.
Everything electrically compatable with your SCSI board should work.
Subsection B : Common Problems
Subsection C : Device Files
SCSI generic devices use character major 21. Due to constraints
imposed by Linux's use of a 16 bit dev_t, minor numbers are dynamically
assigned from 0, one per device, with
/dev/sg0
corresponding to the lowest numerical target/lun on the first
SCSI board.
--
Boycott USL/Novell for their absurd anti-BSDI lawsuit. | Drew Eckhardt,
Condemn Colorado for Amendment Two. | Professional Linux
Use Linux, the fast, flexible, and free 386 unix | Consultant
Will administer Unix for food | drew@cs.Colorado.EDU