Linux Driver for Mylex DAC960/AcceleRAID/eXtremeRAID PCI RAID Controllers

			Version 2.2.11 for Linux 2.2.19
			Version 2.4.11 for Linux 2.4.12

			      PRODUCTION RELEASE

				11 October 2001

			       Leonard N. Zubkoff
			       Dandelion Digital
			       lnz@dandelion.com

	 Copyright 1998-2001 by Leonard N. Zubkoff <lnz@dandelion.com>


				 INTRODUCTION

Mylex, Inc. designs and manufactures a variety of high performance PCI RAID
controllers.  Mylex Corporation is located at 34551 Ardenwood Blvd., Fremont,
California 94555, USA and can be reached at 510.796.6100 or on the World Wide
Web at http://www.mylex.com.  Mylex Technical Support can be reached by
electronic mail at mylexsup@us.ibm.com, by voice at 510.608.2400, or by FAX at
510.745.7715.  Contact information for offices in Europe and Japan is available
on their Web site.

The latest information on Linux support for DAC960 PCI RAID Controllers, as
well as the most recent release of this driver, will always be available from
my Linux Home Page at URL "http://www.dandelion.com/Linux/".  The Linux DAC960
driver supports all current Mylex PCI RAID controllers including the new
eXtremeRAID 2000/3000 and AcceleRAID 352/170/160 models which have an entirely
new firmware interface from the older eXtremeRAID 1100, AcceleRAID 150/200/250,
and DAC960PJ/PG/PU/PD/PL.  See below for a complete controller list as well as
minimum firmware version requirements.  For simplicity, in most places this
documentation refers to DAC960 generically rather than explicitly listing all
the supported models.

Driver bug reports should be sent via electronic mail to "lnz@dandelion.com".
Please include with the bug report the complete configuration messages reported
by the driver at startup, along with any subsequent system messages relevant to
the controller's operation, and a detailed description of your system's
hardware configuration.  Driver bugs are actually quite rare; if you encounter
problems with disks being marked offline, for example, please contact Mylex
Technical Support as the problem is related to the hardware configuration
rather than the Linux driver.

Please consult the RAID controller documentation for detailed information
regarding installation and configuration of the controllers.  This document
primarily provides information specific to the Linux support.


				DRIVER FEATURES

The DAC960 RAID controllers are supported solely as high performance RAID
controllers, not as interfaces to arbitrary SCSI devices.  The Linux DAC960
driver operates at the block device level, the same level as the SCSI and IDE
drivers.  Unlike other RAID controllers currently supported on Linux, the
DAC960 driver is not dependent on the SCSI subsystem, and hence avoids all the
complexity and unnecessary code that would be associated with an implementation
as a SCSI driver.  The DAC960 driver is designed for as high a performance as
possible with no compromises or extra code for compatibility with lower
performance devices.  The DAC960 driver includes extensive error logging and
online configuration management capabilities.  Except for initial configuration
of the controller and adding new disk drives, most everything can be handled
from Linux while the system is operational.

The DAC960 driver is architected to support up to 8 controllers per system.
Each DAC960 parallel SCSI controller can support up to 15 disk drives per
channel, for a maximum of 60 drives on a four channel controller; the fibre
channel eXtremeRAID 3000 controller supports up to 125 disk drives per loop for
a total of 250 drives.  The drives installed on a controller are divided into
one or more "Drive Groups", and then each Drive Group is subdivided further
into 1 to 32 "Logical Drives".  Each Logical Drive has a specific RAID Level
and caching policy associated with it, and it appears to Linux as a single
block device.  Logical Drives are further subdivided into up to 7 partitions
through the normal Linux and PC disk partitioning schemes.  Logical Drives are
also known as "System Drives", and Drive Groups are also called "Packs".  Both
terms are in use in the Mylex documentation; I have chosen to standardize on
the more generic "Logical Drive" and "Drive Group".

DAC960 RAID disk devices are named in the style of the obsolete Device File
System (DEVFS).  The device corresponding to Logical Drive D on Controller C
is referred to as /dev/rd/cCdD, and the partitions are called /dev/rd/cCdDp1
through /dev/rd/cCdDp7.  For example, partition 3 of Logical Drive 5 on
Controller 2 is referred to as /dev/rd/c2d5p3.  Note that unlike with SCSI
disks the device names will not change in the event of a disk drive failure.
The DAC960 driver is assigned major numbers 48 - 55 with one major number per
controller.  The 8 bits of minor number are divided into 5 bits for the Logical
Drive and 3 bits for the partition.


	  SUPPORTED DAC960/AcceleRAID/eXtremeRAID PCI RAID CONTROLLERS

The following list comprises the supported DAC960, AcceleRAID, and eXtremeRAID
PCI RAID Controllers as of the date of this document.  It is recommended that
anyone purchasing a Mylex PCI RAID Controller not in the following table
contact the author beforehand to verify that it is or will be supported.

eXtremeRAID 3000
	    1 Wide Ultra-2/LVD SCSI channel
	    2 External Fibre FC-AL channels
	    233MHz StrongARM SA 110 Processor
	    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
	    32MB/64MB ECC SDRAM Memory

eXtremeRAID 2000
	    4 Wide Ultra-160 LVD SCSI channels
	    233MHz StrongARM SA 110 Processor
	    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
	    32MB/64MB ECC SDRAM Memory

AcceleRAID 352
	    2 Wide Ultra-160 LVD SCSI channels
	    100MHz Intel i960RN RISC Processor
	    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
	    32MB/64MB ECC SDRAM Memory

AcceleRAID 170
	    1 Wide Ultra-160 LVD SCSI channel
	    100MHz Intel i960RM RISC Processor
	    16MB/32MB/64MB ECC SDRAM Memory

AcceleRAID 160 (AcceleRAID 170LP)
	    1 Wide Ultra-160 LVD SCSI channel
	    100MHz Intel i960RS RISC Processor
	    Built in 16M ECC SDRAM Memory
	    PCI Low Profile Form Factor - fit for 2U height

eXtremeRAID 1100 (DAC1164P)
	    3 Wide Ultra-2/LVD SCSI channels
	    233MHz StrongARM SA 110 Processor
	    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
	    16MB/32MB/64MB Parity SDRAM Memory with Battery Backup

AcceleRAID 250 (DAC960PTL1)
	    Uses onboard Symbios SCSI chips on certain motherboards
	    Also includes one onboard Wide Ultra-2/LVD SCSI Channel
	    66MHz Intel i960RD RISC Processor
	    4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory

AcceleRAID 200 (DAC960PTL0)
	    Uses onboard Symbios SCSI chips on certain motherboards
	    Includes no onboard SCSI Channels
	    66MHz Intel i960RD RISC Processor
	    4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory

AcceleRAID 150 (DAC960PRL)
	    Uses onboard Symbios SCSI chips on certain motherboards
	    Also includes one onboard Wide Ultra-2/LVD SCSI Channel
	    33MHz Intel i960RP RISC Processor
	    4MB Parity EDO Memory

DAC960PJ    1/2/3 Wide Ultra SCSI-3 Channels
	    66MHz Intel i960RD RISC Processor
	    4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory

DAC960PG    1/2/3 Wide Ultra SCSI-3 Channels
	    33MHz Intel i960RP RISC Processor
	    4MB/8MB ECC EDO Memory

DAC960PU    1/2/3 Wide Ultra SCSI-3 Channels
	    Intel i960CF RISC Processor
	    4MB/8MB EDRAM or 2MB/4MB/8MB/16MB/32MB DRAM Memory

DAC960PD    1/2/3 Wide Fast SCSI-2 Channels
	    Intel i960CF RISC Processor
	    4MB/8MB EDRAM or 2MB/4MB/8MB/16MB/32MB DRAM Memory

DAC960PL    1/2/3 Wide Fast SCSI-2 Channels
	    Intel i960 RISC Processor
	    2MB/4MB/8MB/16MB/32MB DRAM Memory

DAC960P	    1/2/3 Wide Fast SCSI-2 Channels
	    Intel i960 RISC Processor
	    2MB/4MB/8MB/16MB/32MB DRAM Memory

For the eXtremeRAID 2000/3000 and AcceleRAID 352/170/160, firmware version
6.00-01 or above is required.

For the eXtremeRAID 1100, firmware version 5.06-0-52 or above is required.

For the AcceleRAID 250, 200, and 150, firmware version 4.06-0-57 or above is
required.

For the DAC960PJ and DAC960PG, firmware version 4.06-0-00 or above is required.

For the DAC960PU, DAC960PD, DAC960PL, and DAC960P, either firmware version
3.51-0-04 or above is required (for dual Flash ROM controllers), or firmware
version 2.73-0-00 or above is required (for single Flash ROM controllers)

Please note that not all SCSI disk drives are suitable for use with DAC960
controllers, and only particular firmware versions of any given model may
actually function correctly.  Similarly, not all motherboards have a BIOS that
properly initializes the AcceleRAID 250, AcceleRAID 200, AcceleRAID 150,
DAC960PJ, and DAC960PG because the Intel i960RD/RP is a multi-function device.
If in doubt, contact Mylex RAID Technical Support (mylexsup@us.ibm.com) to
verify compatibility.  Mylex makes available a hard disk compatibility list at
http://www.mylex.com/support/hdcomp/hd-lists.html.


			      DRIVER INSTALLATION

This distribution was prepared for Linux kernel version 2.2.19 or 2.4.12.

To install the DAC960 RAID driver, you may use the following commands,
replacing "/usr/src" with wherever you keep your Linux kernel source tree:

  cd /usr/src
  tar -xvzf DAC960-2.2.11.tar.gz (or DAC960-2.4.11.tar.gz)
  mv README.DAC960 linux/Documentation
  mv DAC960.[ch] linux/drivers/block
  patch -p0 < DAC960.patch (if DAC960.patch is included)
  cd linux
  make config
  make bzImage (or zImage)

Then install "arch/i386/boot/bzImage" or "arch/i386/boot/zImage" as your
standard kernel, run lilo if appropriate, and reboot.

To create the necessary devices in /dev, the "make_rd" script included in
"DAC960-Utilities.tar.gz" from http://www.dandelion.com/Linux/ may be used.
LILO 21 and FDISK v2.9 include DAC960 support; also included in this archive
are patches to LILO 20 and FDISK v2.8 that add DAC960 support, along with
statically linked executables of LILO and FDISK.  This modified version of LILO
will allow booting from a DAC960 controller and/or mounting the root file
system from a DAC960.

Red Hat Linux 6.0 and SuSE Linux 6.1 include support for Mylex PCI RAID
controllers.  Installing directly onto a DAC960 may be problematic from other
Linux distributions until their installation utilities are updated.


			      INSTALLATION NOTES

Before installing Linux or adding DAC960 logical drives to an existing Linux
system, the controller must first be configured to provide one or more logical
drives using the BIOS Configuration Utility or DACCF.  Please note that since
there are only at most 6 usable partitions on each logical drive, systems
requiring more partitions should subdivide a drive group into multiple logical
drives, each of which can have up to 6 usable partitions.  Also, note that with
large disk arrays it is advisable to enable the 8GB BIOS Geometry (255/63)
rather than accepting the default 2GB BIOS Geometry (128/32); failing to so do
will cause the logical drive geometry to have more than 65535 cylinders which
will make it impossible for FDISK to be used properly.  The 8GB BIOS Geometry
can be enabled by configuring the DAC960 BIOS, which is accessible via Alt-M
during the BIOS initialization sequence.

For maximum performance and the most efficient E2FSCK performance, it is
recommended that EXT2 file systems be built with a 4KB block size and 16 block
stride to match the DAC960 controller's 64KB default stripe size.  The command
"mke2fs -b 4096 -R stride=16 <device>" is appropriate.  Unless there will be a
large number of small files on the file systems, it is also beneficial to add
the "-i 16384" option to increase the bytes per inode parameter thereby
reducing the file system metadata.  Finally, on systems that will only be run
with Linux 2.2 or later kernels it is beneficial to enable sparse superblocks
with the "-s 1" option.


		      DAC960 ANNOUNCEMENTS MAILING LIST

The DAC960 Announcements Mailing List provides a forum for informing Linux
users of new driver releases and other announcements regarding Linux support
for DAC960 PCI RAID Controllers.  To join the mailing list, send a message to
"dac960-announce-request@dandelion.com" with the line "subscribe" in the
message body.


		CONTROLLER CONFIGURATION AND STATUS MONITORING

The DAC960 RAID controllers running firmware 4.06 or above include a Background
Initialization facility so that system downtime is minimized both for initial
installation and subsequent configuration of additional storage.  The BIOS
Configuration Utility (accessible via Alt-R during the BIOS initialization
sequence) is used to quickly configure the controller, and then the logical