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Based on kernel version 2.6.27. Page generated on 2008-10-13 09:53 EST.

1	   Linux Driver for Mylex DAC960/AcceleRAID/eXtremeRAID PCI RAID Controllers
2	
3				Version 2.2.11 for Linux 2.2.19
4				Version 2.4.11 for Linux 2.4.12
5	
6				      PRODUCTION RELEASE
7	
8					11 October 2001
9	
10				       Leonard N. Zubkoff
11				       Dandelion Digital
12				       lnz[AT]dandelion[DOT]com
13	
14		 Copyright 1998-2001 by Leonard N. Zubkoff <lnz[AT]dandelion[DOT]com>
15	
16	
17					 INTRODUCTION
18	
19	Mylex, Inc. designs and manufactures a variety of high performance PCI RAID
20	controllers.  Mylex Corporation is located at 34551 Ardenwood Blvd., Fremont,
21	California 94555, USA and can be reached at 510.796.6100 or on the World Wide
22	Web at http://www.mylex.com.  Mylex Technical Support can be reached by
23	electronic mail at mylexsup[AT]us.ibm.com, by voice at 510.608[DOT]2400, or by FAX at
24	510.745.7715.  Contact information for offices in Europe and Japan is available
25	on their Web site.
26	
27	The latest information on Linux support for DAC960 PCI RAID Controllers, as
28	well as the most recent release of this driver, will always be available from
29	my Linux Home Page at URL "http://www.dandelion.com/Linux/".  The Linux DAC960
30	driver supports all current Mylex PCI RAID controllers including the new
31	eXtremeRAID 2000/3000 and AcceleRAID 352/170/160 models which have an entirely
32	new firmware interface from the older eXtremeRAID 1100, AcceleRAID 150/200/250,
33	and DAC960PJ/PG/PU/PD/PL.  See below for a complete controller list as well as
34	minimum firmware version requirements.  For simplicity, in most places this
35	documentation refers to DAC960 generically rather than explicitly listing all
36	the supported models.
37	
38	Driver bug reports should be sent via electronic mail to "lnz[AT]dandelion.com"[DOT]
39	Please include with the bug report the complete configuration messages reported
40	by the driver at startup, along with any subsequent system messages relevant to
41	the controller's operation, and a detailed description of your system's
42	hardware configuration.  Driver bugs are actually quite rare; if you encounter
43	problems with disks being marked offline, for example, please contact Mylex
44	Technical Support as the problem is related to the hardware configuration
45	rather than the Linux driver.
46	
47	Please consult the RAID controller documentation for detailed information
48	regarding installation and configuration of the controllers.  This document
49	primarily provides information specific to the Linux support.
50	
51	
52					DRIVER FEATURES
53	
54	The DAC960 RAID controllers are supported solely as high performance RAID
55	controllers, not as interfaces to arbitrary SCSI devices.  The Linux DAC960
56	driver operates at the block device level, the same level as the SCSI and IDE
57	drivers.  Unlike other RAID controllers currently supported on Linux, the
58	DAC960 driver is not dependent on the SCSI subsystem, and hence avoids all the
59	complexity and unnecessary code that would be associated with an implementation
60	as a SCSI driver.  The DAC960 driver is designed for as high a performance as
61	possible with no compromises or extra code for compatibility with lower
62	performance devices.  The DAC960 driver includes extensive error logging and
63	online configuration management capabilities.  Except for initial configuration
64	of the controller and adding new disk drives, most everything can be handled
65	from Linux while the system is operational.
66	
67	The DAC960 driver is architected to support up to 8 controllers per system.
68	Each DAC960 parallel SCSI controller can support up to 15 disk drives per
69	channel, for a maximum of 60 drives on a four channel controller; the fibre
70	channel eXtremeRAID 3000 controller supports up to 125 disk drives per loop for
71	a total of 250 drives.  The drives installed on a controller are divided into
72	one or more "Drive Groups", and then each Drive Group is subdivided further
73	into 1 to 32 "Logical Drives".  Each Logical Drive has a specific RAID Level
74	and caching policy associated with it, and it appears to Linux as a single
75	block device.  Logical Drives are further subdivided into up to 7 partitions
76	through the normal Linux and PC disk partitioning schemes.  Logical Drives are
77	also known as "System Drives", and Drive Groups are also called "Packs".  Both
78	terms are in use in the Mylex documentation; I have chosen to standardize on
79	the more generic "Logical Drive" and "Drive Group".
80	
81	DAC960 RAID disk devices are named in the style of the obsolete Device File
82	System (DEVFS).  The device corresponding to Logical Drive D on Controller C
83	is referred to as /dev/rd/cCdD, and the partitions are called /dev/rd/cCdDp1
84	through /dev/rd/cCdDp7.  For example, partition 3 of Logical Drive 5 on
85	Controller 2 is referred to as /dev/rd/c2d5p3.  Note that unlike with SCSI
86	disks the device names will not change in the event of a disk drive failure.
87	The DAC960 driver is assigned major numbers 48 - 55 with one major number per
88	controller.  The 8 bits of minor number are divided into 5 bits for the Logical
89	Drive and 3 bits for the partition.
90	
91	
92		  SUPPORTED DAC960/AcceleRAID/eXtremeRAID PCI RAID CONTROLLERS
93	
94	The following list comprises the supported DAC960, AcceleRAID, and eXtremeRAID
95	PCI RAID Controllers as of the date of this document.  It is recommended that
96	anyone purchasing a Mylex PCI RAID Controller not in the following table
97	contact the author beforehand to verify that it is or will be supported.
98	
99	eXtremeRAID 3000
100		    1 Wide Ultra-2/LVD SCSI channel
101		    2 External Fibre FC-AL channels
102		    233MHz StrongARM SA 110 Processor
103		    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
104		    32MB/64MB ECC SDRAM Memory
105	
106	eXtremeRAID 2000
107		    4 Wide Ultra-160 LVD SCSI channels
108		    233MHz StrongARM SA 110 Processor
109		    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
110		    32MB/64MB ECC SDRAM Memory
111	
112	AcceleRAID 352
113		    2 Wide Ultra-160 LVD SCSI channels
114		    100MHz Intel i960RN RISC Processor
115		    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
116		    32MB/64MB ECC SDRAM Memory
117	
118	AcceleRAID 170
119		    1 Wide Ultra-160 LVD SCSI channel
120		    100MHz Intel i960RM RISC Processor
121		    16MB/32MB/64MB ECC SDRAM Memory
122	
123	AcceleRAID 160 (AcceleRAID 170LP)
124		    1 Wide Ultra-160 LVD SCSI channel
125		    100MHz Intel i960RS RISC Processor
126		    Built in 16M ECC SDRAM Memory
127		    PCI Low Profile Form Factor - fit for 2U height
128	
129	eXtremeRAID 1100 (DAC1164P)
130		    3 Wide Ultra-2/LVD SCSI channels
131		    233MHz StrongARM SA 110 Processor
132		    64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots)
133		    16MB/32MB/64MB Parity SDRAM Memory with Battery Backup
134	
135	AcceleRAID 250 (DAC960PTL1)
136		    Uses onboard Symbios SCSI chips on certain motherboards
137		    Also includes one onboard Wide Ultra-2/LVD SCSI Channel
138		    66MHz Intel i960RD RISC Processor
139		    4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory
140	
141	AcceleRAID 200 (DAC960PTL0)
142		    Uses onboard Symbios SCSI chips on certain motherboards
143		    Includes no onboard SCSI Channels
144		    66MHz Intel i960RD RISC Processor
145		    4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory
146	
147	AcceleRAID 150 (DAC960PRL)
148		    Uses onboard Symbios SCSI chips on certain motherboards
149		    Also includes one onboard Wide Ultra-2/LVD SCSI Channel
150		    33MHz Intel i960RP RISC Processor
151		    4MB Parity EDO Memory
152	
153	DAC960PJ    1/2/3 Wide Ultra SCSI-3 Channels
154		    66MHz Intel i960RD RISC Processor
155		    4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory
156	
157	DAC960PG    1/2/3 Wide Ultra SCSI-3 Channels
158		    33MHz Intel i960RP RISC Processor
159		    4MB/8MB ECC EDO Memory
160	
161	DAC960PU    1/2/3 Wide Ultra SCSI-3 Channels
162		    Intel i960CF RISC Processor
163		    4MB/8MB EDRAM or 2MB/4MB/8MB/16MB/32MB DRAM Memory
164	
165	DAC960PD    1/2/3 Wide Fast SCSI-2 Channels
166		    Intel i960CF RISC Processor
167		    4MB/8MB EDRAM or 2MB/4MB/8MB/16MB/32MB DRAM Memory
168	
169	DAC960PL    1/2/3 Wide Fast SCSI-2 Channels
170		    Intel i960 RISC Processor
171		    2MB/4MB/8MB/16MB/32MB DRAM Memory
172	
173	DAC960P	    1/2/3 Wide Fast SCSI-2 Channels
174		    Intel i960 RISC Processor
175		    2MB/4MB/8MB/16MB/32MB DRAM Memory
176	
177	For the eXtremeRAID 2000/3000 and AcceleRAID 352/170/160, firmware version
178	6.00-01 or above is required.
179	
180	For the eXtremeRAID 1100, firmware version 5.06-0-52 or above is required.
181	
182	For the AcceleRAID 250, 200, and 150, firmware version 4.06-0-57 or above is
183	required.
184	
185	For the DAC960PJ and DAC960PG, firmware version 4.06-0-00 or above is required.
186	
187	For the DAC960PU, DAC960PD, DAC960PL, and DAC960P, either firmware version
188	3.51-0-04 or above is required (for dual Flash ROM controllers), or firmware
189	version 2.73-0-00 or above is required (for single Flash ROM controllers)
190	
191	Please note that not all SCSI disk drives are suitable for use with DAC960
192	controllers, and only particular firmware versions of any given model may
193	actually function correctly.  Similarly, not all motherboards have a BIOS that
194	properly initializes the AcceleRAID 250, AcceleRAID 200, AcceleRAID 150,
195	DAC960PJ, and DAC960PG because the Intel i960RD/RP is a multi-function device.
196	If in doubt, contact Mylex RAID Technical Support (mylexsup[AT]us.ibm[DOT]com) to
197	verify compatibility.  Mylex makes available a hard disk compatibility list at
198	http://www.mylex.com/support/hdcomp/hd-lists.html.
199	
200	
201				      DRIVER INSTALLATION
202	
203	This distribution was prepared for Linux kernel version 2.2.19 or 2.4.12.
204	
205	To install the DAC960 RAID driver, you may use the following commands,
206	replacing "/usr/src" with wherever you keep your Linux kernel source tree:
207	
208	  cd /usr/src
209	  tar -xvzf DAC960-2.2.11.tar.gz (or DAC960-2.4.11.tar.gz)
210	  mv README.DAC960 linux/Documentation
211	  mv DAC960.[ch] linux/drivers/block
212	  patch -p0 < DAC960.patch (if DAC960.patch is included)
213	  cd linux
214	  make config
215	  make bzImage (or zImage)
216	
217	Then install "arch/i386/boot/bzImage" or "arch/i386/boot/zImage" as your
218	standard kernel, run lilo if appropriate, and reboot.
219	
220	To create the necessary devices in /dev, the "make_rd" script included in
221	"DAC960-Utilities.tar.gz" from http://www.dandelion.com/Linux/ may be used.
222	LILO 21 and FDISK v2.9 include DAC960 support; also included in this archive
223	are patches to LILO 20 and FDISK v2.8 that add DAC960 support, along with
224	statically linked executables of LILO and FDISK.  This modified version of LILO
225	will allow booting from a DAC960 controller and/or mounting the root file
226	system from a DAC960.
227	
228	Red Hat Linux 6.0 and SuSE Linux 6.1 include support for Mylex PCI RAID
229	controllers.  Installing directly onto a DAC960 may be problematic from other
230	Linux distributions until their installation utilities are updated.
231	
232	
233				      INSTALLATION NOTES
234	
235	Before installing Linux or adding DAC960 logical drives to an existing Linux
236	system, the controller must first be configured to provide one or more logical
237	drives using the BIOS Configuration Utility or DACCF.  Please note that since
238	there are only at most 6 usable partitions on each logical drive, systems
239	requiring more partitions should subdivide a drive group into multiple logical
240	drives, each of which can have up to 6 usable partitions.  Also, note that with
241	large disk arrays it is advisable to enable the 8GB BIOS Geometry (255/63)
242	rather than accepting the default 2GB BIOS Geometry (128/32); failing to so do
243	will cause the logical drive geometry to have more than 65535 cylinders which
244	will make it impossible for FDISK to be used properly.  The 8GB BIOS Geometry
245	can be enabled by configuring the DAC960 BIOS, which is accessible via Alt-M
246	during the BIOS initialization sequence.
247	
248	For maximum performance and the most efficient E2FSCK performance, it is
249	recommended that EXT2 file systems be built with a 4KB block size and 16 block
250	stride to match the DAC960 controller's 64KB default stripe size.  The command
251	"mke2fs -b 4096 -R stride=16 <device>" is appropriate.  Unless there will be a
252	large number of small files on the file systems, it is also beneficial to add
253	the "-i 16384" option to increase the bytes per inode parameter thereby
254	reducing the file system metadata.  Finally, on systems that will only be run
255	with Linux 2.2 or later kernels it is beneficial to enable sparse superblocks
256	with the "-s 1" option.
257	
258	
259			      DAC960 ANNOUNCEMENTS MAILING LIST
260	
261	The DAC960 Announcements Mailing List provides a forum for informing Linux
262	users of new driver releases and other announcements regarding Linux support
263	for DAC960 PCI RAID Controllers.  To join the mailing list, send a message to
264	"dac960-announce-request[AT]dandelion[DOT]com" with the line "subscribe" in the
265	message body.
266	
267	
268			CONTROLLER CONFIGURATION AND STATUS MONITORING
269	
270	The DAC960 RAID controllers running firmware 4.06 or above include a Background
271	Initialization facility so that system downtime is minimized both for initial
272	installation and subsequent configuration of additional storage.  The BIOS
273	Configuration Utility (accessible via Alt-R during the BIOS initialization
274	sequence) is used to quickly configure the controller, and then the logical
275	drives that have been created are available for immediate use even while they
276	are still being initialized by the controller.  The primary need for online
277	configuration and status monitoring is then to avoid system downtime when disk
278	drives fail and must be replaced.  Mylex's online monitoring and configuration
279	utilities are being ported to Linux and will become available at some point in
280	the future.  Note that with a SAF-TE (SCSI Accessed Fault-Tolerant Enclosure)
281	enclosure, the controller is able to rebuild failed drives automatically as
282	soon as a drive replacement is made available.
283	
284	The primary interfaces for controller configuration and status monitoring are
285	special files created in the /proc/rd/... hierarchy along with the normal
286	system console logging mechanism.  Whenever the system is operating, the DAC960
287	driver queries each controller for status information every 10 seconds, and
288	checks for additional conditions every 60 seconds.  The initial status of each
289	controller is always available for controller N in /proc/rd/cN/initial_status,
290	and the current status as of the last status monitoring query is available in
291	/proc/rd/cN/current_status.  In addition, status changes are also logged by the
292	driver to the system console and will appear in the log files maintained by
293	syslog.  The progress of asynchronous rebuild or consistency check operations
294	is also available in /proc/rd/cN/current_status, and progress messages are
295	logged to the system console at most every 60 seconds.
296	
297	Starting with the 2.2.3/2.0.3 versions of the driver, the status information
298	available in /proc/rd/cN/initial_status and /proc/rd/cN/current_status has been
299	augmented to include the vendor, model, revision, and serial number (if
300	available) for each physical device found connected to the controller:
301	
302	***** DAC960 RAID Driver Version 2.2.3 of 19 August 1999 *****
303	Copyright 1998-1999 by Leonard N. Zubkoff <lnz[AT]dandelion[DOT]com>
304	Configuring Mylex DAC960PRL PCI RAID Controller
305	  Firmware Version: 4.07-0-07, Channels: 1, Memory Size: 16MB
306	  PCI Bus: 1, Device: 4, Function: 1, I/O Address: Unassigned
307	  PCI Address: 0xFE300000 mapped at 0xA0800000, IRQ Channel: 21
308	  Controller Queue Depth: 128, Maximum Blocks per Command: 128
309	  Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33
310	  Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63
311	  SAF-TE Enclosure Management Enabled
312	  Physical Devices:
313	    0:0  Vendor: IBM       Model: DRVS09D           Revision: 0270
314	         Serial Number:       68016775HA
315	         Disk Status: Online, 17928192 blocks
316	    0:1  Vendor: IBM       Model: DRVS09D           Revision: 0270
317	         Serial Number:       68004E53HA
318	         Disk Status: Online, 17928192 blocks
319	    0:2  Vendor: IBM       Model: DRVS09D           Revision: 0270
320	         Serial Number:       13013935HA
321	         Disk Status: Online, 17928192 blocks
322	    0:3  Vendor: IBM       Model: DRVS09D           Revision: 0270
323	         Serial Number:       13016897HA
324	         Disk Status: Online, 17928192 blocks
325	    0:4  Vendor: IBM       Model: DRVS09D           Revision: 0270
326	         Serial Number:       68019905HA
327	         Disk Status: Online, 17928192 blocks
328	    0:5  Vendor: IBM       Model: DRVS09D           Revision: 0270
329	         Serial Number:       68012753HA
330	         Disk Status: Online, 17928192 blocks
331	    0:6  Vendor: ESG-SHV   Model: SCA HSBP M6       Revision: 0.61
332	  Logical Drives:
333	    /dev/rd/c0d0: RAID-5, Online, 89640960 blocks, Write Thru
334	  No Rebuild or Consistency Check in Progress
335	
336	To simplify the monitoring process for custom software, the special file
337	/proc/rd/status returns "OK" when all DAC960 controllers in the system are
338	operating normally and no failures have occurred, or "ALERT" if any logical
339	drives are offline or critical or any non-standby physical drives are dead.
340	
341	Configuration commands for controller N are available via the special file
342	/proc/rd/cN/user_command.  A human readable command can be written to this
343	special file to initiate a configuration operation, and the results of the
344	operation can then be read back from the special file in addition to being
345	logged to the system console.  The shell command sequence
346	
347	  echo "<configuration-command>" > /proc/rd/c0/user_command
348	  cat /proc/rd/c0/user_command
349	
350	is typically used to execute configuration commands.  The configuration
351	commands are:
352	
353	  flush-cache
354	
355	    The "flush-cache" command flushes the controller's cache.  The system
356	    automatically flushes the cache at shutdown or if the driver module is
357	    unloaded, so this command is only needed to be certain a write back cache
358	    is flushed to disk before the system is powered off by a command to a UPS.
359	    Note that the flush-cache command also stops an asynchronous rebuild or
360	    consistency check, so it should not be used except when the system is being
361	    halted.
362	
363	  kill <channel>:<target-id>
364	
365	    The "kill" command marks the physical drive <channel>:<target-id> as DEAD.
366	    This command is provided primarily for testing, and should not be used
367	    during normal system operation.
368	
369	  make-online <channel>:<target-id>
370	
371	    The "make-online" command changes the physical drive <channel>:<target-id>
372	    from status DEAD to status ONLINE.  In cases where multiple physical drives
373	    have been killed simultaneously, this command may be used to bring all but
374	    one of them back online, after which a rebuild to the final drive is
375	    necessary.
376	
377	    Warning: make-online should only be used on a dead physical drive that is
378	    an active part of a drive group, never on a standby drive.  The command
379	    should never be used on a dead drive that is part of a critical logical
380	    drive; rebuild should be used if only a single drive is dead.
381	
382	  make-standby <channel>:<target-id>
383	
384	    The "make-standby" command changes physical drive <channel>:<target-id>
385	    from status DEAD to status STANDBY.  It should only be used in cases where
386	    a dead drive was replaced after an automatic rebuild was performed onto a
387	    standby drive.  It cannot be used to add a standby drive to the controller
388	    configuration if one was not created initially; the BIOS Configuration
389	    Utility must be used for that currently.
390	
391	  rebuild <channel>:<target-id>
392	
393	    The "rebuild" command initiates an asynchronous rebuild onto physical drive
394	    <channel>:<target-id>.  It should only be used when a dead drive has been
395	    replaced.
396	
397	  check-consistency <logical-drive-number>
398	
399	    The "check-consistency" command initiates an asynchronous consistency check
400	    of <logical-drive-number> with automatic restoration.  It can be used
401	    whenever it is desired to verify the consistency of the redundancy
402	    information.
403	
404	  cancel-rebuild
405	  cancel-consistency-check
406	
407	    The "cancel-rebuild" and "cancel-consistency-check" commands cancel any
408	    rebuild or consistency check operations previously initiated.
409	
410	
411		       EXAMPLE I - DRIVE FAILURE WITHOUT A STANDBY DRIVE
412	
413	The following annotated logs demonstrate the controller configuration and and
414	online status monitoring capabilities of the Linux DAC960 Driver.  The test
415	configuration comprises 6 1GB Quantum Atlas I disk drives on two channels of a
416	DAC960PJ controller.  The physical drives are configured into a single drive
417	group without a standby drive, and the drive group has been configured into two
418	logical drives, one RAID-5 and one RAID-6.  Note that these logs are from an
419	earlier version of the driver and the messages have changed somewhat with newer
420	releases, but the functionality remains similar.  First, here is the current
421	status of the RAID configuration:
422	
423	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
424	***** DAC960 RAID Driver Version 2.0.0 of 23 March 1999 *****
425	Copyright 1998-1999 by Leonard N. Zubkoff <lnz[AT]dandelion[DOT]com>
426	Configuring Mylex DAC960PJ PCI RAID Controller
427	  Firmware Version: 4.06-0-08, Channels: 3, Memory Size: 8MB
428	  PCI Bus: 0, Device: 19, Function: 1, I/O Address: Unassigned
429	  PCI Address: 0xFD4FC000 mapped at 0x8807000, IRQ Channel: 9
430	  Controller Queue Depth: 128, Maximum Blocks per Command: 128
431	  Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33
432	  Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63
433	  Physical Devices:
434	    0:1 - Disk: Online, 2201600 blocks
435	    0:2 - Disk: Online, 2201600 blocks
436	    0:3 - Disk: Online, 2201600 blocks
437	    1:1 - Disk: Online, 2201600 blocks
438	    1:2 - Disk: Online, 2201600 blocks
439	    1:3 - Disk: Online, 2201600 blocks
440	  Logical Drives:
441	    /dev/rd/c0d0: RAID-5, Online, 5498880 blocks, Write Thru
442	    /dev/rd/c0d1: RAID-6, Online, 3305472 blocks, Write Thru
443	  No Rebuild or Consistency Check in Progress
444	
445	gwynedd:/u/lnz# cat /proc/rd/status
446	OK
447	
448	The above messages indicate that everything is healthy, and /proc/rd/status
449	returns "OK" indicating that there are no problems with any DAC960 controller
450	in the system.  For demonstration purposes, while I/O is active Physical Drive
451	1:1 is now disconnected, simulating a drive failure.  The failure is noted by
452	the driver within 10 seconds of the controller's having detected it, and the
453	driver logs the following console status messages indicating that Logical
454	Drives 0 and 1 are now CRITICAL as a result of Physical Drive 1:1 being DEAD:
455	
456	DAC960#0: Physical Drive 1:2 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02
457	DAC960#0: Physical Drive 1:3 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02
458	DAC960#0: Physical Drive 1:1 killed because of timeout on SCSI command
459	DAC960#0: Physical Drive 1:1 is now DEAD
460	DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now CRITICAL
461	DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now CRITICAL
462	
463	The Sense Keys logged here are just Check Condition / Unit Attention conditions
464	arising from a SCSI bus reset that is forced by the controller during its error
465	recovery procedures.  Concurrently with the above, the driver status available
466	from /proc/rd also reflects the drive failure.  The status message in
467	/proc/rd/status has changed from "OK" to "ALERT":
468	
469	gwynedd:/u/lnz# cat /proc/rd/status
470	ALERT
471	
472	and /proc/rd/c0/current_status has been updated:
473	
474	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
475	  ...
476	  Physical Devices:
477	    0:1 - Disk: Online, 2201600 blocks
478	    0:2 - Disk: Online, 2201600 blocks
479	    0:3 - Disk: Online, 2201600 blocks
480	    1:1 - Disk: Dead, 2201600 blocks
481	    1:2 - Disk: Online, 2201600 blocks
482	    1:3 - Disk: Online, 2201600 blocks
483	  Logical Drives:
484	    /dev/rd/c0d0: RAID-5, Critical, 5498880 blocks, Write Thru
485	    /dev/rd/c0d1: RAID-6, Critical, 3305472 blocks, Write Thru
486	  No Rebuild or Consistency Check in Progress
487	
488	Since there are no standby drives configured, the system can continue to access
489	the logical drives in a performance degraded mode until the failed drive is
490	replaced and a rebuild operation completed to restore the redundancy of the
491	logical drives.  Once Physical Drive 1:1 is replaced with a properly
492	functioning drive, or if the physical drive was killed without having failed
493	(e.g., due to electrical problems on the SCSI bus), the user can instruct the
494	controller to initiate a rebuild operation onto the newly replaced drive:
495	
496	gwynedd:/u/lnz# echo "rebuild 1:1" > /proc/rd/c0/user_command
497	gwynedd:/u/lnz# cat /proc/rd/c0/user_command
498	Rebuild of Physical Drive 1:1 Initiated
499	
500	The echo command instructs the controller to initiate an asynchronous rebuild
501	operation onto Physical Drive 1:1, and the status message that results from the
502	operation is then available for reading from /proc/rd/c0/user_command, as well
503	as being logged to the console by the driver.
504	
505	Within 10 seconds of this command the driver logs the initiation of the
506	asynchronous rebuild operation:
507	
508	DAC960#0: Rebuild of Physical Drive 1:1 Initiated
509	DAC960#0: Physical Drive 1:1 Error Log: Sense Key = 6, ASC = 29, ASCQ = 01
510	DAC960#0: Physical Drive 1:1 is now WRITE-ONLY
511	DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 1% completed
512	
513	and /proc/rd/c0/current_status is updated:
514	
515	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
516	  ...
517	  Physical Devices:
518	    0:1 - Disk: Online, 2201600 blocks
519	    0:2 - Disk: Online, 2201600 blocks
520	    0:3 - Disk: Online, 2201600 blocks
521	    1:1 - Disk: Write-Only, 2201600 blocks
522	    1:2 - Disk: Online, 2201600 blocks
523	    1:3 - Disk: Online, 2201600 blocks
524	  Logical Drives:
525	    /dev/rd/c0d0: RAID-5, Critical, 5498880 blocks, Write Thru
526	    /dev/rd/c0d1: RAID-6, Critical, 3305472 blocks, Write Thru
527	  Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 6% completed
528	
529	As the rebuild progresses, the current status in /proc/rd/c0/current_status is
530	updated every 10 seconds:
531	
532	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
533	  ...
534	  Physical Devices:
535	    0:1 - Disk: Online, 2201600 blocks
536	    0:2 - Disk: Online, 2201600 blocks
537	    0:3 - Disk: Online, 2201600 blocks
538	    1:1 - Disk: Write-Only, 2201600 blocks
539	    1:2 - Disk: Online, 2201600 blocks
540	    1:3 - Disk: Online, 2201600 blocks
541	  Logical Drives:
542	    /dev/rd/c0d0: RAID-5, Critical, 5498880 blocks, Write Thru
543	    /dev/rd/c0d1: RAID-6, Critical, 3305472 blocks, Write Thru
544	  Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 15% completed
545	
546	and every minute a progress message is logged to the console by the driver:
547	
548	DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 32% completed
549	DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 63% completed
550	DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 94% completed
551	DAC960#0: Rebuild in Progress: Logical Drive 1 (/dev/rd/c0d1) 94% completed
552	
553	Finally, the rebuild completes successfully.  The driver logs the status of the 
554	logical and physical drives and the rebuild completion:
555	
556	DAC960#0: Rebuild Completed Successfully
557	DAC960#0: Physical Drive 1:1 is now ONLINE
558	DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now ONLINE
559	DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now ONLINE
560	
561	/proc/rd/c0/current_status is updated:
562	
563	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
564	  ...
565	  Physical Devices:
566	    0:1 - Disk: Online, 2201600 blocks
567	    0:2 - Disk: Online, 2201600 blocks
568	    0:3 - Disk: Online, 2201600 blocks
569	    1:1 - Disk: Online, 2201600 blocks
570	    1:2 - Disk: Online, 2201600 blocks
571	    1:3 - Disk: Online, 2201600 blocks
572	  Logical Drives:
573	    /dev/rd/c0d0: RAID-5, Online, 5498880 blocks, Write Thru
574	    /dev/rd/c0d1: RAID-6, Online, 3305472 blocks, Write Thru
575	  Rebuild Completed Successfully
576	
577	and /proc/rd/status indicates that everything is healthy once again:
578	
579	gwynedd:/u/lnz# cat /proc/rd/status
580	OK
581	
582	
583			EXAMPLE II - DRIVE FAILURE WITH A STANDBY DRIVE
584	
585	The following annotated logs demonstrate the controller configuration and and
586	online status monitoring capabilities of the Linux DAC960 Driver.  The test
587	configuration comprises 6 1GB Quantum Atlas I disk drives on two channels of a
588	DAC960PJ controller.  The physical drives are configured into a single drive
589	group with a standby drive, and the drive group has been configured into two
590	logical drives, one RAID-5 and one RAID-6.  Note that these logs are from an
591	earlier version of the driver and the messages have changed somewhat with newer
592	releases, but the functionality remains similar.  First, here is the current
593	status of the RAID configuration:
594	
595	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
596	***** DAC960 RAID Driver Version 2.0.0 of 23 March 1999 *****
597	Copyright 1998-1999 by Leonard N. Zubkoff <lnz[AT]dandelion[DOT]com>
598	Configuring Mylex DAC960PJ PCI RAID Controller
599	  Firmware Version: 4.06-0-08, Channels: 3, Memory Size: 8MB
600	  PCI Bus: 0, Device: 19, Function: 1, I/O Address: Unassigned
601	  PCI Address: 0xFD4FC000 mapped at 0x8807000, IRQ Channel: 9
602	  Controller Queue Depth: 128, Maximum Blocks per Command: 128
603	  Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33
604	  Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63
605	  Physical Devices:
606	    0:1 - Disk: Online, 2201600 blocks
607	    0:2 - Disk: Online, 2201600 blocks
608	    0:3 - Disk: Online, 2201600 blocks
609	    1:1 - Disk: Online, 2201600 blocks
610	    1:2 - Disk: Online, 2201600 blocks
611	    1:3 - Disk: Standby, 2201600 blocks
612	  Logical Drives:
613	    /dev/rd/c0d0: RAID-5, Online, 4399104 blocks, Write Thru
614	    /dev/rd/c0d1: RAID-6, Online, 2754560 blocks, Write Thru
615	  No Rebuild or Consistency Check in Progress
616	
617	gwynedd:/u/lnz# cat /proc/rd/status
618	OK
619	
620	The above messages indicate that everything is healthy, and /proc/rd/status
621	returns "OK" indicating that there are no problems with any DAC960 controller
622	in the system.  For demonstration purposes, while I/O is active Physical Drive
623	1:2 is now disconnected, simulating a drive failure.  The failure is noted by
624	the driver within 10 seconds of the controller's having detected it, and the
625	driver logs the following console status messages:
626	
627	DAC960#0: Physical Drive 1:1 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02
628	DAC960#0: Physical Drive 1:3 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02
629	DAC960#0: Physical Drive 1:2 killed because of timeout on SCSI command
630	DAC960#0: Physical Drive 1:2 is now DEAD
631	DAC960#0: Physical Drive 1:2 killed because it was removed
632	DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now CRITICAL
633	DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now CRITICAL
634	
635	Since a standby drive is configured, the controller automatically begins
636	rebuilding onto the standby drive:
637	
638	DAC960#0: Physical Drive 1:3 is now WRITE-ONLY
639	DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 4% completed
640	
641	Concurrently with the above, the driver status available from /proc/rd also
642	reflects the drive failure and automatic rebuild.  The status message in
643	/proc/rd/status has changed from "OK" to "ALERT":
644	
645	gwynedd:/u/lnz# cat /proc/rd/status
646	ALERT
647	
648	and /proc/rd/c0/current_status has been updated:
649	
650	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
651	  ...
652	  Physical Devices:
653	    0:1 - Disk: Online, 2201600 blocks
654	    0:2 - Disk: Online, 2201600 blocks
655	    0:3 - Disk: Online, 2201600 blocks
656	    1:1 - Disk: Online, 2201600 blocks
657	    1:2 - Disk: Dead, 2201600 blocks
658	    1:3 - Disk: Write-Only, 2201600 blocks
659	  Logical Drives:
660	    /dev/rd/c0d0: RAID-5, Critical, 4399104 blocks, Write Thru
661	    /dev/rd/c0d1: RAID-6, Critical, 2754560 blocks, Write Thru
662	  Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 4% completed
663	
664	As the rebuild progresses, the current status in /proc/rd/c0/current_status is
665	updated every 10 seconds:
666	
667	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
668	  ...
669	  Physical Devices:
670	    0:1 - Disk: Online, 2201600 blocks
671	    0:2 - Disk: Online, 2201600 blocks
672	    0:3 - Disk: Online, 2201600 blocks
673	    1:1 - Disk: Online, 2201600 blocks
674	    1:2 - Disk: Dead, 2201600 blocks
675	    1:3 - Disk: Write-Only, 2201600 blocks
676	  Logical Drives:
677	    /dev/rd/c0d0: RAID-5, Critical, 4399104 blocks, Write Thru
678	    /dev/rd/c0d1: RAID-6, Critical, 2754560 blocks, Write Thru
679	  Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 40% completed
680	
681	and every minute a progress message is logged on the console by the driver:
682	
683	DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 40% completed
684	DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 76% completed
685	DAC960#0: Rebuild in Progress: Logical Drive 1 (/dev/rd/c0d1) 66% completed
686	DAC960#0: Rebuild in Progress: Logical Drive 1 (/dev/rd/c0d1) 84% completed
687	
688	Finally, the rebuild completes successfully.  The driver logs the status of the 
689	logical and physical drives and the rebuild completion:
690	
691	DAC960#0: Rebuild Completed Successfully
692	DAC960#0: Physical Drive 1:3 is now ONLINE
693	DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now ONLINE
694	DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now ONLINE
695	
696	/proc/rd/c0/current_status is updated:
697	
698	***** DAC960 RAID Driver Version 2.0.0 of 23 March 1999 *****
699	Copyright 1998-1999 by Leonard N. Zubkoff <lnz[AT]dandelion[DOT]com>
700	Configuring Mylex DAC960PJ PCI RAID Controller
701	  Firmware Version: 4.06-0-08, Channels: 3, Memory Size: 8MB
702	  PCI Bus: 0, Device: 19, Function: 1, I/O Address: Unassigned
703	  PCI Address: 0xFD4FC000 mapped at 0x8807000, IRQ Channel: 9
704	  Controller Queue Depth: 128, Maximum Blocks per Command: 128
705	  Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33
706	  Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63
707	  Physical Devices:
708	    0:1 - Disk: Online, 2201600 blocks
709	    0:2 - Disk: Online, 2201600 blocks
710	    0:3 - Disk: Online, 2201600 blocks
711	    1:1 - Disk: Online, 2201600 blocks
712	    1:2 - Disk: Dead, 2201600 blocks
713	    1:3 - Disk: Online, 2201600 blocks
714	  Logical Drives:
715	    /dev/rd/c0d0: RAID-5, Online, 4399104 blocks, Write Thru
716	    /dev/rd/c0d1: RAID-6, Online, 2754560 blocks, Write Thru
717	  Rebuild Completed Successfully
718	
719	and /proc/rd/status indicates that everything is healthy once again:
720	
721	gwynedd:/u/lnz# cat /proc/rd/status
722	OK
723	
724	Note that the absence of a viable standby drive does not create an "ALERT"
725	status.  Once dead Physical Drive 1:2 has been replaced, the controller must be
726	told that this has occurred and that the newly replaced drive should become the
727	new standby drive:
728	
729	gwynedd:/u/lnz# echo "make-standby 1:2" > /proc/rd/c0/user_command
730	gwynedd:/u/lnz# cat /proc/rd/c0/user_command
731	Make Standby of Physical Drive 1:2 Succeeded
732	
733	The echo command instructs the controller to make Physical Drive 1:2 into a
734	standby drive, and the status message that results from the operation is then
735	available for reading from /proc/rd/c0/user_command, as well as being logged to
736	the console by the driver.  Within 60 seconds of this command the driver logs:
737	
738	DAC960#0: Physical Drive 1:2 Error Log: Sense Key = 6, ASC = 29, ASCQ = 01
739	DAC960#0: Physical Drive 1:2 is now STANDBY
740	DAC960#0: Make Standby of Physical Drive 1:2 Succeeded
741	
742	and /proc/rd/c0/current_status is updated:
743	
744	gwynedd:/u/lnz# cat /proc/rd/c0/current_status
745	  ...
746	  Physical Devices:
747	    0:1 - Disk: Online, 2201600 blocks
748	    0:2 - Disk: Online, 2201600 blocks
749	    0:3 - Disk: Online, 2201600 blocks
750	    1:1 - Disk: Online, 2201600 blocks
751	    1:2 - Disk: Standby, 2201600 blocks
752	    1:3 - Disk: Online, 2201600 blocks
753	  Logical Drives:
754	    /dev/rd/c0d0: RAID-5, Online, 4399104 blocks, Write Thru
755	    /dev/rd/c0d1: RAID-6, Online, 2754560 blocks, Write Thru
756	  Rebuild Completed Successfully
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