.\" $OpenBSD: raidctl.8,v 1.1 1999/01/11 14:49:44 niklas Exp $ .\" .\" .\" Copyright (c) 1998 The NetBSD Foundation, Inc. .\" All rights reserved. .\" .\" This code is derived from software contributed to The NetBSD Foundation .\" by Greg Oster .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the NetBSD .\" Foundation, Inc. and its contributors. .\" 4. Neither the name of The NetBSD Foundation nor the names of its .\" contributors may be used to endorse or promote products derived .\" from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS .\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED .\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS .\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE .\" POSSIBILITY OF SUCH DAMAGE. .\" .\" .\" Copyright (c) 1995 Carnegie-Mellon University. .\" All rights reserved. .\" .\" Author: Mark Holland .\" .\" Permission to use, copy, modify and distribute this software and .\" its documentation is hereby granted, provided that both the copyright .\" notice and this permission notice appear in all copies of the .\" software, derivative works or modified versions, and any portions .\" thereof, and that both notices appear in supporting documentation. .\" .\" CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" .\" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND .\" FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. .\" .\" Carnegie Mellon requests users of this software to return to .\" .\" Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU .\" School of Computer Science .\" Carnegie Mellon University .\" Pittsburgh PA 15213-3890 .\" .\" any improvements or extensions that they make and grant Carnegie the .\" rights to redistribute these changes. .\" .Dd November 6, 1998 .Dt RAIDCTL 8 .Os .Sh NAME .Nm raidctl .Nd configuration utility for the RAIDframe disk driver .Sh SYNOPSIS .Nm .Fl c Ar config_file Ar dev .Nm "" .Fl C Ar dev .Nm "" .Fl f Ar component Ar dev .Nm "" .Fl F Ar component Ar dev .Nm "" .Fl r Ar dev .Nm "" .Fl R Ar dev .Nm "" .Fl s Ar dev .Nm "" .Fl u Ar dev .Sh DESCRIPTION .Nm is the user-land control program for .Xr raid 4 , Ns the RAIDframe disk device. .Nm is primarily used to dynamically configure and unconfigure RAIDframe disk devices. For more information about the RAIDframe disk device, see .Xr raid 4 . .Pp This document assumes the reader has at least rudimentary knowledge of RAID and RAID concepts. .Pp The command-line options for .Nm are as follows: .Bl -tag -width indent .It Fl c Ar config_file Ar dev Configure the RAIDframe device .Ar dev according to the configuration given in .Ar config_file . A description of the contents of .Ar config_file is given later. .It Fl C Ar dev Initiate a copyback of reconstructed data from a spare disk to it's original disk. This is performed after a component has failed, and the failed drive has been reconstructed onto a spare drive. .It Fl f Ar component Ar dev This marks the specified .Ar component as having failed, but does not initiate a reconstruction of that component. .It Fl F Ar component Ar dev Fails the specified .Ar component of the device, and immediately begin a reconstruction of the failed disk onto an available hot spare. This is the mechanism used to start the reconstruction process if a component does have a hardware failure. .It Fl r Ar dev Re-write the parity on the device. This .Ar MUST be done before the RAID device is labeled and before filesystems are created on the RAID device, and is normally used after a system crash (and before a .Xr fsck 8 ) Ns to ensure the integrity of the parity. .It Fl R Ar dev Check the status of component reconstruction. The output indicates the amount of progress achieved in reconstructing a failed component. .It Fl s Ar dev Display the status of the RAIDframe device for each of the components and spares. .It Fl u Ar dev Unconfigure the RAIDframe device. .El .Pp The device used by .Nm is specified by .Ar dev . .Ar dev may be either the full name of the device, e.g. /dev/rraid0d, for the i386 architecture, and /dev/rraid0c for all others, or just simply raid0 (for /dev/rraid0d). .Pp The format of the configuration file is complex, and only an abbreviated treatment is given here. In the configuration files, a .Sq # indicates the beginning of a comment. .Pp There are 4 required sections of a configuration file, and 2 optional components. Each section begins with a .Sq START , followed by the section name, and the confuration parameters associated with that section. The first section is the .Sq array section, and it specifies the number of rows, columns, and spare disks in the RAID array. For example: .Bd -unfilled -offset indent START array 1 3 0 .Ed .Pp indicates an array with 1 row, 3 columns, and 0 spare disks. Note that allthough multi-dimenstional arrays may be specified, they are .Ar NOT supported in the driver. .Pp The second section, the .Sq disks section, specifies the actual components of the device. For example: .Bd -unfilled -offset indent START disks /dev/sd0e /dev/sd1e /dev/sd2e .Ed .Pp specifies the three component disks to be used in the RAID device. If any of the specified drives cannot be found when the RAID device is configured, then they will be marked as .Sq failed , and the system will operate in degraded mode. Note that it is .Ar imperative that the order of the components in the configuration file does not change between configurations of a RAID device. Changing the order of the components (at least at the time of this writing) will result in data loss. .Pp The next section, which is the .Sq spare section, is optional, and, if present, specifies the devices to be used as .Sq hot spares -- devices which are on-line, but are not actively used by the RAID driver unless one of the main components fail. A simple .Sq spare section might be: .Bd -unfilled -offset indent START spare /dev/sd3e .Ed .Pp for a configuration with a single spare component. If no spare drives are to be used in the configuration, then the .Sq spare section may be ommitted. .Pp The next section is the .Sq layout section. This section describes the general layout parameters for the RAID device, and provides such information as sectors per stripe unit, stripe units per parity unit, stripe units per reconstruction unit, and the parity configuration to use. This section might look like: .Bd -unfilled -offset indent START layout # sectPerSU SUsPerParityUnit SUsPerReconUnit RAID_level 32 1 1 5 .Ed .Pp The sectors per stripe unit specifies, in blocks, the interleave factor; i.e. the number of contiguous sectors to be written to each component for a single stripe. Appropriate selection of this value (32 in this example) is the subject of much research in RAID architectures. The stripe units per parity unit and stripe units per reconstruction unit are normally each set to 1. While certain values above 1 are permitted, a discussion of valid values and the consequences of using anything other than 1 are outside the scope of this document. The last value in this section (5 in this example) indicates the parity configuration desired. Valid entries include: .Bl -tag -width inde .It 0 RAID level 0. No parity, only simple striping. .It 1 RAID level 1. Mirroring. .It 4 RAID level 4. Striping across components, with parity stored on the last component. .It 5 RAID level 5. Striping across components, parity distributed across all components. .El .Pp There are other valid entries here, including those for Even-Odd parity, RAID level 5 with rotated sparing, Chained declustering, and Interleaved declustering, but as of this writing the code for those parity operations has not been tested with .Ox . .Pp The next required section is the .Sq queue section. This is most often specified as: .Bd -unfilled -offset indent START queue fifo 1 .Ed .Pp where the queueing method is specified as fifo (first-in, first-out), and the size of the per-component queue is limited to 1 requests. A value of 1 is quite conservative here, and values of 100 or more may been used to increase the driver performance. Other queuing methods may also be specified, but a discussion of them is beyond the scope of this document. .Pp The final section, the .Sq debug section, is optional. For more details on this the reader is referred to the RAIDframe documentation dissussed in the .Sx HISTORY section. See .Sx EXAMPLES for a more complete configuration file example. .Sh EXAMPLES The examples in this section will focus on a RAID 5 configuration. Other RAID configurations will behave similarly. It is highly recommended that before using the RAID driver for real filesystems that the system administrator(s) have used .Ar all of the options for .Nm , and that they understand how the component reconstruction process works. While this example is not created as a tutorial, the steps shown here can be easily dupilicated using four equal-sized partitions from any number of disks (including all four from a single disk). .Pp The primary uses of .Nm is to configure and unconfigure .Xr raid 4 devices. To configure the device, a configuration file which looks something like: .Bd -unfilled -offset indent START array # numRow numCol numSpare 1 3 1 START disks /dev/sd1e /dev/sd2e /dev/sd3e START spare /dev/sd4e START layout # sectPerSU SUsPerParityUnit SUsPerReconUnit RAID_level_5 32 1 1 5 START queue fifo 100 .Ed .Pp is first created. In short, this configuration file specifies a RAID 5 configuration consisting of the disks /dev/sd1e, /dev/sd2e, and /dev/sd3e, with /dev/sd4e available as a .Sq hot spare in case one of the three main drives should fail. If the above configuration is in a file called .Sq rfconfig , raid device 0 can be configured with: .Bd -unfilled -offset indent raidctl -c rfconfig raid0 .Ed .Pp The above is equivalent to the following: .Bd -unfilled -offset indent raidctl -c rfconfig /dev/rraid0d .Ed .Pp on the i386 architecture. On all other architectures, /dev/rraid0c is used in place of /dev/rraid0d. .Pp To see how the device is doing, the following will show the status: .Bd -unfilled -offset indent raidctl -s raid0 .Ed .Pp The output will look something like: .Bd -unfilled -offset indent Components: /dev/sd1e: optimal /dev/sd2e: optimal /dev/sd3e: optimal Spares: /dev/sd4e [0][0]: spare .Ed .Pp This indicates that all is well with the RAID array. If this is the first time this RAID array has been configured, or the system is just being brought up after an unclean shutdown, it is necessary to ensure that the parity values are correct. This can be done via: .Bd -unfilled -offset indent raidctl -r raid0 .Ed .Pp Once this is done, it is then safe to perform .Xr disklabel 8 , Ns .Xr newfs 8 , Ns or .Xr fsck 8 on the device or its filesystems. .Pp If for some reason (perhaps to test reconstruction) it is necessary to pretend a drive has failed, the following will perform that function: .Bd -unfilled -offset indent raidctl -f /dev/sd2e raid0 .Ed .Pp The system will then be performing all operations in degraded mode, were missing data is re-computed from existing data and the parity. In this case, obtaining the status of raid0 will return: .Bd -unfilled -offset indent Components: /dev/sd1e: optimal /dev/sd2e: failed /dev/sd3e: optimal Spares: /dev/sd4e [0][0]: spare .Ed .Pp Note that with the use of .Fl f a reconstruction has not been started. To both fail the disk and start a reconstruction, the .Fl F option must be used. (The .Fl f option may be used first, and then the .Fl F option used later, on the same disk, if desired.) Immediately after the reconstruction is started, the status will report: .Bd -unfilled -offset indent Components: /dev/sd1e: optimal /dev/sd2e: reconstructing /dev/sd3e: optimal Spares: /dev/sd4e [0][0]: used_spare .Ed .Pp This indicates that a reconstruction is in progress. To find out how the reconstruction is progressing the .Fl R option may be used. This will indicate the progress in terms of the percentage of the reconstruction that is completed. When the reconstruction is finished the .Fl s option will show: .Bd -unfilled -offset indent Components: /dev/sd1e: optimal /dev/sd2e: spared /dev/sd3e: optimal Spares: /dev/sd4e [0][0]: used_spare .Ed .Pp At this point there are at least two options. First, if /dev/sd2e is known to be good (i.e. the failure was either caused by .Fl f or .Fl F , or the failed disk was replaced), then a copyback of the data can be initiated with the .Fl C option. In this example, this would copy the entire contents of /dev/sd4e to /dev/sd2e. Once the copyback procedure is complete, the status of the device would be: .Bd -unfilled -offset indent Components: /dev/sd1e: optimal /dev/sd2e: optimal /dev/sd3e: optimal Spares: /dev/sd4e [0][0]: spare .Ed .Pp and the system is back to normal operation. .Pp The second option after the reconstruction is to simply use /dev/sd4e in place of /dev/sd2e in the configuration file. For example, the configuration file (in part) might now look like: .Bd -unfilled -offset indent START array 1 3 0 START drives /dev/sd1e /dev/sd4e /dev/sd3e .Ed .Pp This can be done as /dev/sd4e is completely interchangeable with /dev/sd2e at this point. Note that extreme care must be taken when changing the order of the drives in a configuration. This is one of the few instances where the devices and/or their orderings can be changed without loss of data! In general, the ordering of components in a configuration file should .Ar never be changed. .Pp The final operation performed by .Nm is to unconfigure a .Xr raid 4 device. This is accomplished via a simple: .Bd -unfilled -offset indent raidctl -u raid0 .Ed .Pp at which point the device is ready to be reconfigured. .Sh WARNINGS Certain RAID levels (1, 4, 5, 6, and others) can protect against some data loss due to component failure. However the loss of two components of a RAID 4 or 5 system, or the loss of a single component of a RAID 0 system will result in the entire filesystem being lost. RAID is .Ar NOT a substitute for good backup practices. .Pp Recomputation of parity .Ar MUST be performed whenever there is a chance that it may have been compromised. This includes after system crashes, or before a RAID device has been used for the first time. Failure to keep parity correct will be catastrophic should a component ever fail -- it is better to use RAID 0 and get the additional space and speed, than it is to use parity, but not keep the parity correct. At least with RAID 0 there is no perception of increased data security. .Pp .Sh FILES .Bl -tag -width /dev/XXrXraidX -compact .It Pa /dev/{,r}raid* .Nm device special files. .El .Pp .Sh SEE ALSO .Xr raid 4 , .Xr ccd 4 , .Xr rc 8 .Sh HISTORY RAIDframe is a framework for rapid prototyping of RAID structures developed by the folks at the Parallel Data Laboratory at Carnegie Mellon University (CMU). A more complete description of the internals and functionality of RAIDframe is found in the paper "RAIDframe: A Rapid Prototyping Tool for RAID Systems", by William V. Courtright II, Garth Gibson, Mark Holland, LeAnn Neal Reilly, and Jim Zelenka, and published by the Parallel Data Laboratory of Carnegie Mellon University. .Pp The .Nm command first appeared as a program in CMU's RAIDframe v1.1 distribution. This version of .Nm is a complete re-write, and first appeared in .Nx 1.4 . .Sh COPYRIGHT .Bd -unfilled The RAIDframe Copyright is as follows: Copyright (c) 1994-1996 Carnegie-Mellon University. All rights reserved. Permission to use, copy, modify and distribute this software and its documentation is hereby granted, provided that both the copyright notice and this permission notice appear in all copies of the software, derivative works or modified versions, and any portions thereof, and that both notices appear in supporting documentation. CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. Carnegie Mellon requests users of this software to return to Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU School of Computer Science Carnegie Mellon University Pittsburgh PA 15213-3890 any improvements or extensions that they make and grant Carnegie the rights to redistribute these changes. .Ed