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Sat Mar 2 13:23:44 2013 UTC (13 months, 3 weeks ago) by jdf
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Finally, some more cosmetics. This is the last one.

# NetBSD RAIDframe

## RAIDframe Introduction

### About RAIDframe

NetBSD uses the [CMU RAIDframe](http://www.pdl.cmu.edu/RAIDframe/) software for
its RAID subsystem. NetBSD is the primary platform for RAIDframe development.
RAIDframe can also be found in older versions of FreeBSD and OpenBSD. NetBSD
also has another way of bundling disks, the
[ccd(4)](http://netbsd.gw.com/cgi-bin/man-cgi?ccd+4+NetBSD-5.0.1+i386) subsystem
(see [Concatenated Disk Device](/guide/ccd)). You should possess some [basic
knowledge](http://www.acnc.com/04_00.html) about RAID concepts and terminology
before continuing. You should also be at least familiar with the different
levels of RAID - Adaptec provides an [excellent
reference](http://www.adaptec.com/en-US/_common/compatibility/_education/RAID_level_compar_wp.htm),
and the [raid(4)](http://netbsd.gw.com/cgi-bin/man-cgi?raid+4+NetBSD-5.0.1+i386)
manpage contains a short overview too.

### A warning about Data Integrity, Backups, and High Availability

RAIDframe is a Software RAID implementation, as opposed to Hardware RAID. As
such, it does not need special disk controllers supported by NetBSD. System
administrators should give a great deal of consideration to whether software
RAID or hardware RAID is more appropriate for their "Mission Critical"
applications. For some projects you might consider the use of many of the
hardware RAID devices [supported by
NetBSD](http://www.NetBSD.org/support/hardware/). It is truly at your discretion
what type of RAID you use, but it is recommend that you consider factors such
as: manageability, commercial vendor support, load-balancing and failover, etc.

Depending on the RAID level used, RAIDframe does provide redundancy in the event
of a hardware failure. However, it is *not* a replacement for reliable backups!
Software and user-error can still cause data loss. RAIDframe may be used as a
mechanism for facilitating backups in systems without backup hardware, but this
is not an ideal configuration. Finally, with regard to "high availability", RAID
is only a very small component to ensuring data availability.

Once more for good measure: *Back up your data!*

### Hardware versus Software RAID

If you run a server, it will most probably already have a Hardware RAID
controller. There are reasons for and against using a Software RAID, depending
on the scenario.

In general, a Software RAID is well suited for low-IO system disks. If you run a
Software RAID, you can exchange disks and disk controllers, or even move the
disks to a completely different machine. The computational overhead for the RAID
is negligible if there is only few disk IO operations.

If you need much IO, you should use a Hardware RAID. With a Software RAID, the
redundancy data has to be transferred via the bus your disk controller is
connected to. With a Hardware RAID, you transfer data only once - the redundancy
computation and transfer is done by the controller.

### Getting Help

If you encounter problems using RAIDframe, you have several options for
obtaining help.

 1. Read the RAIDframe man pages:
    [raid(4)](http://netbsd.gw.com/cgi-bin/man-cgi?raid+4+NetBSD-5.0.1+i386) and
    [raidctl(8)](http://netbsd.gw.com/cgi-bin/man-cgi?raidctl+8+NetBSD-5.0.1+i386)
    thoroughly.

 2. Search the mailing list archives. Unfortunately, there is no NetBSD list
    dedicated to RAIDframe support. Depending on the nature of the problem, posts
    tend to end up in a variety of lists. At a very minimum, search
    [netbsd-help](http://mail-index.NetBSD.org/netbsd-help/),
    [netbsd-users@NetBSD.org](http://mail-index.NetBSD.org/netbsd-users/),
    [current-users@NetBSD.org](http://mail-index.NetBSD.org/current-users/). Also
    search the list for the NetBSD platform on which you are using RAIDframe:
    port-*`${ARCH}`*@NetBSD.org.

    *Caution*: Because RAIDframe is constantly undergoing development, some information in
	mailing list archives has the potential of being dated and inaccurate.

 3. Search the [Problem Report
    database](http://www.NetBSD.org/support/send-pr.html).

 4. If your problem persists: Post to the mailing list most appropriate
    (judgment call). Collect as much verbosely detailed information as possible
    before posting: Include your
    [dmesg(8)](http://netbsd.gw.com/cgi-bin/man-cgi?dmesg+8+NetBSD-5.0.1+i386)
    output from `/var/run/dmesg.boot`, your kernel
    [config(5)](http://netbsd.gw.com/cgi-bin/man-cgi?config+5+NetBSD-5.0.1+i386) ,
    your `/etc/raid[0-9].conf`, any relevant errors on `/dev/console`,
    `/var/log/messages`, or to `stdout/stderr` of
    [raidctl(8)](http://netbsd.gw.com/cgi-bin/man-cgi?raidctl+8+NetBSD-5.0.1+i386).
    The output of **raidctl -s** (if available) will be useful as well. Also
    include details on the troubleshooting steps you've taken thus far, exactly
    when the problem started, and any notes on recent changes that may have
    prompted the problem to develop. Remember to be patient when waiting for a
    response.

## Setup RAIDframe Support

The use of RAID will require software and hardware configuration changes.

### Kernel Support

The GENERIC kernel already has support for RAIDframe. If you have built a custom
kernel for your environment the kernel configuration must have the following
options:

    pseudo-device   raid            8       # RAIDframe disk driver
    options         RAID_AUTOCONFIG         # auto-configuration of RAID components

The RAID support must be detected by the NetBSD kernel, which can be checked by
looking at the output of the
[dmesg(8)](http://netbsd.gw.com/cgi-bin/man-cgi?dmesg+8+NetBSD-5.0.1+i386)
command.

    # dmesg|grep -i raid
    Kernelized RAIDframe activated

Historically, the kernel must also contain static mappings between bus addresses
and device nodes in `/dev`. This used to ensure consistency of devices within
RAID sets in the event of a device failure after reboot. Since NetBSD 1.6,
however, using the auto-configuration features of RAIDframe has been recommended
over statically mapping devices. The auto-configuration features allow drives to
move around on the system, and RAIDframe will automatically determine which
components belong to which RAID sets.

### Power Redundancy and Disk Caching

If your system has an Uninterruptible Power Supply (UPS), if your system has
redundant power supplies, or your disk controller has a battery, you should
consider enabling the read and write caches on your drives. On systems with
redundant power, this will improve drive performance. On systems without
redundant power, the write cache could endanger the integrity of RAID data in
the event of a power loss.

The [dkctl(8)](http://netbsd.gw.com/cgi-bin/man-cgi?dkctl+8+NetBSD-5.0.1+i386)
utility to can be used for this on all kinds of disks that support the operation
(SCSI, EIDE, SATA, ...):

    # dkctl wd0 getcache
    /dev/rwd0d: read cache enabled
    /dev/rwd0d: read cache enable is not changeable
    /dev/rwd0d: write cache enable is changeable
    /dev/rwd0d: cache parameters are not savable
    # dkctl wd0 setcache rw
    # dkctl wd0 getcache
    /dev/rwd0d: read cache enabled
    /dev/rwd0d: write-back cache enabled
    /dev/rwd0d: read cache enable is not changeable
    /dev/rwd0d: write cache enable is changeable
    /dev/rwd0d: cache parameters are not savable

## Example: RAID-1 Root Disk

This example explains how to setup RAID-1 root disk. With RAID-1 components are
mirrored and therefore the server can be fully functional in the event of a
single component failure. The goal is to provide a level of redundancy that will
allow the system to encounter a component failure on either component disk in
the RAID and:

 * Continue normal operations until a maintenance window can be scheduled.
 * Or, in the unlikely event that the component failure causes a system reboot,
   be able to quickly reconfigure the system to boot from the remaining
   component (platform dependent).

![RAID-1 Disk Logical Layout](/guide/images/raidframe_raidl1-diskdia.png)
**RAID-1 Disk Logical Layout**

Because RAID-1 provides both redundancy and performance improvements, its most
practical application is on critical "system" partitions such as `/`, `/usr`,
`/var`, `swap`, etc., where read operations are more frequent than write
operations. For other file systems, such as `/home` or `/var/`, other RAID
levels might be considered (see the references above). If one were simply
creating a generic RAID-1 volume for a non-root file system, the cookie-cutter
examples from the man page could be followed, but because the root volume must
be bootable, certain special steps must be taken during initial setup.

*Note*: This example will outline a process that differs only slightly between
the i386 and sparc64 platforms. In an attempt to reduce excessive duplication of
content, where differences do exist and are cosmetic in nature, they will be
pointed out using a section such as this. If the process is drastically
different, the process will branch into separate, platform dependent steps.

### Pseudo-Process Outline

Although a much more refined process could be developed using a custom copy of
NetBSD installed on custom-developed removable media, presently the NetBSD
install media lacks RAIDframe tools and support, so the following pseudo process
has become the de facto standard for setting up RAID-1 Root.

 1. Install a stock NetBSD onto Disk0 of your system.


    ![Perform generic install onto Disk0/wd0](/guide/images/raidframe_r1r-pp1.png)
    **Perform generic install onto Disk0/wd0**

 2. Use the installed system on Disk0/wd0 to setup a RAID Set composed of
    Disk1/wd1 only.

    ![Setup RAID Set](/guide/images/raidframe_r1r-pp2.png)
    **Setup RAID Set**

 3. Reboot the system off the Disk1/wd1 with the newly created RAID volume.


    ![Reboot using Disk1/wd1 of RAID](/guide/images/raidframe_r1r-pp3.png)
    **Reboot using Disk1/wd1 of RAID**


 4. Add/re-sync Disk0/wd0 back into the RAID set.

    ![Mirror Disk1/wd1 back to Disk0/wd0](/guide/images/raidframe_r1r-pp4.png)
    **Mirror Disk1/wd1 back to Disk0/wd0**

### Hardware Review

At present, the alpha, amd64, i386, pmax, sparc, sparc64, and vax NetBSD
platforms support booting from RAID-1. Booting is not supported from any other
RAID level. Booting from a RAID set is accomplished by teaching the 1st stage
boot loader to understand both 4.2BSD/FFS and RAID partitions. The 1st boot
block code only needs to know enough about the disk partitions and file systems
to be able to read the 2nd stage boot blocks. Therefore, at any time, the
system's BIOS/firmware must be able to read a drive with 1st stage boot blocks
installed. On the i386 platform, configuring this is entirely dependent on the
vendor of the controller card/host bus adapter to which your disks are
connected. On sparc64 this is controlled by the IEEE 1275 Sun OpenBoot Firmware.

This article assumes two identical IDE disks (`/dev/wd{0,1}`) which we are going
to mirror (RAID-1). These disks are identified as:

    # grep ^wd /var/run/dmesg.boot
    wd0 at atabus0 drive 0: <WDC WD100BB-75CLB0>
    wd0: drive supports 16-sector PIO transfers, LBA addressing
    wd0: 9541 MB, 19386 cyl, 16 head, 63 sec, 512 bytes/sect x 19541088 sectors
    wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 5 (Ultra/100)
    wd0(piixide0:0:0): using PIO mode 4, Ultra-DMA mode 2 (Ultra/33) (using DMA data transfers)
    
    wd1 at atabus1 drive 0: <WDC WD100BB-75CLB0>
    wd1: drive supports 16-sector PIO transfers, LBA addressing
    wd1: 9541 MB, 19386 cyl, 16 head, 63 sec, 512 bytes/sect x 19541088 sectors
    wd1: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 5 (Ultra/100)
    wd1(piixide0:1:0): using PIO mode 4, Ultra-DMA mode 2 (Ultra/33) (using DMA data transfers)

*Note*: If you are using SCSI, replace `/dev/{,r}wd{0,1}` with
`/dev/{,r}sd{0,1}`.

In this example, both disks are jumpered as Master on separate channels on the
same controller. You usually wouldn't want to have both disks on the same bus on
the same controller; this creates a single point of failure. Ideally you would
have the disks on separate channels on separate controllers. Nonetheless, in
most cases the most critical point is the hard disk, so having redundant
channels or controllers is not that important. Plus, having more channels or
controllers increases costs. Some SCSI controllers have multiple channels on the
same controller, however, a SCSI bus reset on one channel could adversely affect
the other channel if the ASIC/IC becomes overloaded. The trade-off with two
controllers is that twice the bandwidth is used on the system bus. For purposes
of simplification, this example shows two disks on different channels on the
same controller.

*Note*: RAIDframe requires that all components be of the same size. Actually, it
will use the lowest common denominator among components of dissimilar sizes. For
purposes of illustration, the example uses two disks of identical geometries.
Also, consider the availability of replacement disks if a component suffers a
critical hardware failure.

*Tip*: Two disks of identical vendor model numbers could have different
geometries if the drive possesses "grown defects". Use a low-level program to
examine the grown defects table of the disk. These disks are obviously
suboptimal candidates for use in RAID and should be avoided.

### Initial Install on Disk0/wd0

Perform a very generic installation onto your Disk0/wd0. Follow the `INSTALL`
instructions for your platform. Install all the sets but do not bother
customizing anything other than the kernel as it will be overwritten.

*Tip*: On i386, during the sysinst install, when prompted if you want to `use
the entire disk for NetBSD`, answer `yes`.

 * [Installing NetBSD: Preliminary considerations and preparations](/guide/inst)
 * [NetBSD/i386 Install](http://ftp.NetBSD.org/pub/NetBSD/NetBSD-5.0.2/i386/INSTALL.html)
 * [NetBSD/sparc64 Install](http://ftp.NetBSD.org/pub/NetBSD/NetBSD-5.0.2/sparc64/INSTALL.html)

Once the installation is complete, you should examine the
[disklabel(8)](http://netbsd.gw.com/cgi-bin/man-cgi?disklabel+8+NetBSD-5.0.1+i386)
and [fdisk(8)](http://netbsd.gw.com/cgi-bin/man-cgi?fdisk+8+NetBSD-5.0.1+i386) /
[sunlabel(8)](http://netbsd.gw.com/cgi-bin/man-cgi?sunlabel+8+NetBSD-5.0.1+i386)
outputs on the system:

    # df
    Filesystem   1K-blocks        Used       Avail %Cap Mounted on
    /dev/wd0a       9487886      502132     8511360   5% /

On i386:

    # disklabel -r wd0
    type: unknown
    disk: Disk00
    label:
    flags:
    bytes/sector: 512
    sectors/track: 63
    tracks/cylinder: 16
    sectors/cylinder: 1008
    cylinders: 19386
    total sectors: 19541088
    rpm: 3600
    interleave: 1
    trackskew: 0
    cylinderskew: 0
    headswitch: 0           # microseconds
    track-to-track seek: 0  # microseconds
    drivedata: 0
    
    16 partitions:
    #        size    offset     fstype [fsize bsize cpg/sgs]
     a:  19276992        63     4.2BSD   1024  8192 46568  # (Cyl.      0* - 19124*)
     b:    264033  19277055       swap                     # (Cyl.  19124* - 19385)
     c:  19541025        63     unused      0     0        # (Cyl.      0* - 19385)
     d:  19541088         0     unused      0     0        # (Cyl.      0 - 19385)
    
    # fdisk /dev/rwd0d
    Disk: /dev/rwd0d
    NetBSD disklabel disk geometry:
    cylinders: 19386, heads: 16, sectors/track: 63 (1008 sectors/cylinder)
    total sectors: 19541088
    
    BIOS disk geometry:
    cylinders: 1023, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
    total sectors: 19541088
    
    Partition table:
    0: NetBSD (sysid 169)
        start 63, size 19541025 (9542 MB, Cyls 0-1216/96/1), Active
    1: <UNUSED>
    2: <UNUSED>
    3: <UNUSED>
    Bootselector disabled.
    First active partition: 0

On Sparc64 the command and output differ slightly:

    # disklabel -r wd0
    type: unknown
    disk: Disk0
    [...snip...]
    8 partitions:
    #        size    offset     fstype [fsize bsize cpg/sgs]
     a:  19278000         0     4.2BSD   1024  8192 46568  # (Cyl.      0 -  19124)
     b:    263088  19278000       swap                     # (Cyl.  19125 -  19385)
     c:  19541088         0     unused      0     0        # (Cyl.      0 -  19385)
    
    # sunlabel /dev/rwd0c
    sunlabel> P
    a: start cyl =      0, size = 19278000 (19125/0/0 - 9413.09Mb)
    b: start cyl =  19125, size =   263088 (261/0/0 - 128.461Mb)
    c: start cyl =      0, size = 19541088 (19386/0/0 - 9541.55Mb)

### Preparing Disk1/wd1

Once you have a stock install of NetBSD on Disk0/wd0, you are ready to begin.
Disk1/wd1 will be visible and unused by the system. To setup Disk1/wd1, you will
use
[disklabel(8)](http://netbsd.gw.com/cgi-bin/man-cgi?disklabel+8+NetBSD-5.0.1+i386)
to allocate the entire second disk to the RAID-1 set.

*Tip*: The best way to ensure that Disk1/wd1 is completely empty is to 'zero'
out the first few sectors of the disk with
[dd(1)](http://netbsd.gw.com/cgi-bin/man-cgi?dd+1+NetBSD-5.0.1+i386) . This will
erase the MBR (i386) or Sun disk label (sparc64), as well as the NetBSD disk
label. If you make a mistake at any point during the RAID setup process, you can
always refer to this process to restore the disk to an empty state.

*Note*: On sparc64, use `/dev/rwd1c` instead of `/dev/rwd1d`!

    # dd if=/dev/zero of=/dev/rwd1d bs=8k count=1
    1+0 records in
    1+0 records out
    8192 bytes transferred in 0.003 secs (2730666 bytes/sec)

Once this is complete, on i386, verify that both the MBR and NetBSD disk labels
are gone. On sparc64, verify that the Sun Disk label is gone as well.

On i386:

    # fdisk /dev/rwd1d
    
    fdisk: primary partition table invalid, no magic in sector 0
    Disk: /dev/rwd1d
    NetBSD disklabel disk geometry:
    cylinders: 19386, heads: 16, sectors/track: 63 (1008 sectors/cylinder)
    total sectors: 19541088
    
    BIOS disk geometry:
    cylinders: 1023, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
    total sectors: 19541088
    
    Partition table:
    0: <UNUSED>
    1: <UNUSED>
    2: <UNUSED>
    3: <UNUSED>
    Bootselector disabled.
    
    # disklabel -r wd1
    
    [...snip...]
    16 partitions:
    #        size    offset     fstype [fsize bsize cpg/sgs]
     c:  19541025        63     unused      0     0        # (Cyl.      0* - 19385)
     d:  19541088         0     unused      0     0        # (Cyl.      0 - 19385)

On sparc64:

    # sunlabel /dev/rwd1c
    
    sunlabel: bogus label on `/dev/wd1c' (bad magic number)
    
    # disklabel -r wd1
    
    [...snip...]
    3 partitions:
    #        size    offset     fstype [fsize bsize cpg/sgs]
     c:  19541088         0     unused      0     0        # (Cyl.      0 -  19385)
    disklabel: boot block size 0
    disklabel: super block size 0

Now that you are certain the second disk is empty, on i386 you must establish
the MBR on the second disk using the values obtained from Disk0/wd0 above. We
must remember to mark the NetBSD partition active or the system will not boot.
You must also create a NetBSD disklabel on Disk1/wd1 that will enable a RAID
volume to exist upon it. On sparc64, you will need to simply
[disklabel(8)](http://netbsd.gw.com/cgi-bin/man-cgi?disklabel+8+NetBSD-5.0.1+i386)
the second disk which will write the proper Sun Disk Label.

*Tip*:
[disklabel(8)](http://netbsd.gw.com/cgi-bin/man-cgi?disklabel+8+NetBSD-5.0.1+i386)
will use your shell' s environment variable `$EDITOR` variable to edit the
disklabel. The default is
[vi(1)](http://netbsd.gw.com/cgi-bin/man-cgi?vi+1+NetBSD-5.0.1+i386)

On i386:

    # fdisk -0ua /dev/rwd1d
    fdisk: primary partition table invalid, no magic in sector 0
    Disk: /dev/rwd1d
    NetBSD disklabel disk geometry:
    cylinders: 19386, heads: 16, sectors/track: 63 (1008 sectors/cylinder)
    total sectors: 19541088
    
    BIOS disk geometry:
    cylinders: 1023, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
    total sectors: 19541088
    
    Do you want to change our idea of what BIOS thinks? [n]
    
    Partition 0:
    <UNUSED>
    The data for partition 0 is:
    <UNUSED>
    sysid: [0..255 default: 169]
    start: [0..1216cyl default: 63, 0cyl, 0MB]
    size: [0..1216cyl default: 19541025, 1216cyl, 9542MB]
    bootmenu: []
    Do you want to change the active partition? [n] y
    Choosing 4 will make no partition active.
    active partition: [0..4 default: 0] 0
    Are you happy with this choice? [n] y
    
    We haven't written the MBR back to disk yet.  This is your last chance.
    Partition table:
    0: NetBSD (sysid 169)
        start 63, size 19541025 (9542 MB, Cyls 0-1216/96/1), Active
    1: <UNUSED>
    2: <UNUSED>
    3: <UNUSED>
    Bootselector disabled.
    Should we write new partition table? [n] y
    
    # disklabel -r -e -I wd1
    type: unknown
    disk: Disk1
    label:
    flags:
    bytes/sector: 512
    sectors/track: 63
    tracks/cylinder: 16
    sectors/cylinder: 1008
    cylinders: 19386
    total sectors: 19541088
    [...snip...]
    16 partitions:
    #        size    offset     fstype [fsize bsize cpg/sgs]
     a:  19541025        63       RAID                     # (Cyl.      0*-19385)
     c:  19541025        63     unused      0     0        # (Cyl.      0*-19385)
     d:  19541088         0     unused      0     0        # (Cyl.      0 -19385)

On sparc64:

    # disklabel -r -e -I wd1
    type: unknown
    disk: Disk1
    label:
    flags:
    bytes/sector: 512
    sectors/track: 63
    tracks/cylinder: 16
    sectors/cylinder: 1008
    cylinders: 19386
    total sectors: 19541088
    [...snip...]
    3 partitions:
    #        size    offset     fstype [fsize bsize cpg/sgs]
     a:  19541088         0       RAID                     # (Cyl.      0 -  19385)
     c:  19541088         0     unused      0     0        # (Cyl.      0 -  19385)
    
    # sunlabel /dev/rwd1c
    sunlabel> P
    a: start cyl =      0, size = 19541088 (19386/0/0 - 9541.55Mb)
    c: start cyl =      0, size = 19541088 (19386/0/0 - 9541.55Mb)

*Note*: On i386, the `c:` and `d:` slices are reserved. `c:` represents the
NetBSD portion of the disk. `d:` represents the entire disk. Because we want to
allocate the entire NetBSD MBR partition to RAID, and because `a:` resides
within the bounds of `c:`, the `a:` and `c:` slices have same size and offset
values and sizes. The offset must start at a track boundary (an increment of
sectors matching the sectors/track value in the disk label). On sparc64 however,
`c:` represents the entire NetBSD partition in the Sun disk label and `d:` is
not reserved. Also note that sparc64's `c:` and `a:` require no offset from the
beginning of the disk, however if they should need to be, the offset must start
at a cylinder boundary (an increment of sectors matching the sectors/cylinder
value).

### Initializing the RAID Device

Next we create the configuration file for the RAID set/volume. Traditionally,
RAIDframe configuration files belong in `/etc` and would be read and initialized
at boot time, however, because we are creating a bootable RAID volume, the
configuration data will actually be written into the RAID volume using the
*auto-configure* feature. Therefore, files are needed only during the initial
setup and should not reside in `/etc`.

    # vi /var/tmp/raid0.conf
    START array
    1 2 0
    
    START disks
    absent
    /dev/wd1a
    
    START layout
    128 1 1 1
    
    START queue
    fifo 100

Note that `absent` means a non-existing disk. This will allow us to establish
the RAID volume with a bogus component that we will substitute for Disk0/wd0 at
a later time.

Next we configure the RAID device and initialize the serial number to something
unique. In this example we use a "YYYYMMDD*`Revision`*" scheme. The format you
choose is entirely at your discretion, however the scheme you choose should
ensure that no two RAID sets use the same serial number at the same time.

After that we initialize the RAID set for the first time, safely ignoring the
errors regarding the bogus component.

    # raidctl -v -C /var/tmp/raid0.conf raid0
    Ignoring missing component at column 0
    raid0: Component absent being configured at col: 0
             Column: 0 Num Columns: 0
             Version: 0 Serial Number: 0 Mod Counter: 0
             Clean: No Status: 0
    Number of columns do not match for: absent
    absent is not clean!
    raid0: Component /dev/wd1a being configured at col: 1
             Column: 0 Num Columns: 0
             Version: 0 Serial Number: 0 Mod Counter: 0
             Clean: No Status: 0
    Column out of alignment for: /dev/wd1a
    Number of columns do not match for: /dev/wd1a
    /dev/wd1a is not clean!
    raid0: There were fatal errors
    raid0: Fatal errors being ignored.
    raid0: RAID Level 1
    raid0: Components: component0[**FAILED**] /dev/wd1a
    raid0: Total Sectors: 19540864 (9541 MB)
    # raidctl -v -I 2009122601 raid0
    # raidctl -v -i raid0
    Initiating re-write of parity
    raid0: Error re-writing parity!
    Parity Re-write status:
    
    # tail -1 /var/log/messages
    Dec 26 00:00:30  /netbsd: raid0: Error re-writing parity!
    # raidctl -v -s raid0
    Components:
              component0: failed
               /dev/wd1a: optimal
    No spares.
    component0 status is: failed.  Skipping label.
    Component label for /dev/wd1a:
       Row: 0, Column: 1, Num Rows: 1, Num Columns: 2
       Version: 2, Serial Number: 2009122601, Mod Counter: 7
       Clean: No, Status: 0
       sectPerSU: 128, SUsPerPU: 1, SUsPerRU: 1
       Queue size: 100, blocksize: 512, numBlocks: 19540864
       RAID Level: 1
       Autoconfig: No
       Root partition: No
       Last configured as: raid0
    Parity status: DIRTY
    Reconstruction is 100% complete.
    Parity Re-write is 100% complete.
    Copyback is 100% complete.

### Setting up Filesystems

*Caution*: The root filesystem must begin at sector 0 of the RAID device. If
not, the primary boot loader will be unable to find the secondary boot loader.

The RAID device is now configured and available. The RAID device is a pseudo
disk-device. It will be created with a default disk label. You must now
determine the proper sizes for disklabel slices for your production environment.
For purposes of simplification in this example, our system will have 8.5
gigabytes dedicated to `/` as `/dev/raid0a` and the rest allocated to `swap`
as `/dev/raid0b`.

*Caution*: This is an unrealistic disk layout for a production server; the
NetBSD Guide can expand on proper partitioning technique. See [Installing
NetBSD: Preliminary considerations and preparations*](inst).

*Note*: Note that 1 GB is 2\*1024\*1024=2097152 blocks (1 block is 512 bytes, or
0.5 kilobytes). Despite what the underlying hardware composing a RAID set is,
the RAID pseudo disk will always have 512 bytes/sector.

*Note*: In our example, the space allocated to the underlying `a:` slice
composing the RAID set differed between i386 and sparc64, therefore the total
sectors of the RAID volumes differs:

On i386:

     # disklabel -r -e -I raid0
    type: RAID
    disk: raid
    label: fictitious
    flags:
    bytes/sector: 512
    sectors/track: 128
    tracks/cylinder: 8
    sectors/cylinder: 1024
    cylinders: 19082
    total sectors: 19540864
    rpm: 3600
    interleave: 1
    trackskew: 0
    cylinderskew: 0
    headswitch: 0 # microseconds
    track-to-track seek: 0 # microseconds
    drivedata: 0
    
    #        size    offset     fstype [fsize bsize cpg/sgs]
     a:  19015680         0     4.2BSD      0     0     0  # (Cyl.      0 - 18569)
     b:    525184  19015680       swap                     # (Cyl.  18570 - 19082*)
     d:  19540864         0     unused      0     0        # (Cyl.      0 - 19082*)

On sparc64:

    # disklabel -r -e -I raid0
    [...snip...]
    total sectors: 19539968
    [...snip...]
    3 partitions:
    #        size    offset     fstype [fsize bsize cpg/sgs]
     a:  19251200         0     4.2BSD      0     0     0  # (Cyl.      0 -  18799)
     b:    288768  19251200       swap                     # (Cyl.  18800 -  19081)
     c:  19539968         0     unused      0     0        # (Cyl.      0 -  19081)

Next, format the newly created `/` partition as a 4.2BSD FFSv1 File System:

    # newfs -O 1 /dev/rraid0a
    /dev/rraid0a: 9285.0MB (19015680 sectors) block size 16384, fragment size 2048
            using 51 cylinder groups of 182.06MB, 11652 blks, 23040 inodes.
    super-block backups (for fsck -b #) at:
    32, 372896, 745760, 1118624, 1491488, 1864352, 2237216, 2610080, 2982944,
    ...............................................................................
    
    # fsck -fy /dev/rraid0a
    ** /dev/rraid0a
    ** File system is already clean
    ** Last Mounted on
    ** Phase 1 - Check Blocks and Sizes
    ** Phase 2 - Check Pathnames
    ** Phase 3 - Check Connectivity
    ** Phase 4 - Check Reference Counts
    ** Phase 5 - Check Cyl groups
    1 files, 1 used, 4679654 free (14 frags, 584955 blocks, 0.0% fragmentation)

### Migrating System to RAID

The new RAID filesystems are now ready for use. We mount them under `/mnt` and
copy all files from the old system. This can be done using
[dump(8)](http://netbsd.gw.com/cgi-bin/man-cgi?dump+8+NetBSD-5.0.1+i386) or
[pax(1)](http://netbsd.gw.com/cgi-bin/man-cgi?pax+1+NetBSD-5.0.1+i386).

    # mount /dev/raid0a /mnt
    # df -h /mnt
    Filesystem        Size       Used      Avail %Cap Mounted on
    /dev/raid0a       8.9G       2.0K       8.5G   0% /mnt
    # cd /; pax -v -X -rw -pe . /mnt
    [...snip...]

The NetBSD install now exists on the RAID filesystem. We need to fix the
mount-points in the new copy of `/etc/fstab` or the system will not come up
correctly. Replace instances of `wd0` with `raid0`.

The swap should be unconfigured upon shutdown to avoid parity errors on the RAID
device. This can be done with a simple, one-line setting in `/etc/rc.conf`.

    # vi /mnt/etc/rc.conf
    swapoff=YES

Next, the boot loader must be installed on Disk1/wd1. Failure to install the
loader on Disk1/wd1 will render the system un-bootable if Disk0/wd0 fails. You
should hope your system won't have to reboot when wd0 fails.

*Tip*: Because the BIOS/CMOS menus in many i386 based systems are misleading
with regard to device boot order. I highly recommend utilizing the `-o
timeout=X` option supported by the i386 1st stage boot loader. Setup unique
values for each disk as a point of reference so that you can easily determine
from which disk the system is booting.

*Caution*: Although it may seem logical to install the 1st stage boot block into
`/dev/rwd1{c,d}` (which is historically correct with NetBSD 1.6.x
[installboot(8)](http://netbsd.gw.com/cgi-bin/man-cgi?installboot+8+NetBSD-5.0.1+i386)
, this is no longer the case. If you make this mistake, the boot sector will
become irrecoverably damaged and you will need to start the process over again.

On i386, install the boot loader into `/dev/rwd1a`:

    # /usr/sbin/installboot -o timeout=30 -v /dev/rwd1a /usr/mdec/bootxx_ffsv1
    File system:         /dev/rwd1a
    Primary bootstrap:   /usr/mdec/bootxx_ffsv1
    Ignoring PBR with invalid magic in sector 0 of `/dev/rwd1a'
    Boot options:        timeout 30, flags 0, speed 9600, ioaddr 0, console pc

On sparc64, install the boot loader into `/dev/rwd1a` as well, however the `-o`
flag is unsupported (and un-needed thanks to OpenBoot):

    # /usr/sbin/installboot -v /dev/rwd1a /usr/mdec/bootblk
    File system:         /dev/rwd1a
    Primary bootstrap:   /usr/mdec/bootblk
    Bootstrap start sector: 1
    Bootstrap byte count:   5140
    Writing bootstrap

Finally the RAID set must be made auto-configurable and the system should be
rebooted. After the reboot everything is mounted from the RAID devices.

    # raidctl -v -A root raid0
    raid0: Autoconfigure: Yes
    raid0: Root: Yes
    # tail -2 /var/log/messages
    raid0: New autoconfig value is: 1
    raid0: New rootpartition value is: 1
    # raidctl -v -s raid0
    [...snip...]
       Autoconfig: Yes
       Root partition: Yes
       Last configured as: raid0
    [...snip...]
    # shutdown -r now

*Warning*: Always use
[shutdown(8)](http://netbsd.gw.com/cgi-bin/man-cgi?shutdown+8+NetBSD-5.0.1+i386)
when shutting down. Never simply use
[reboot(8)](http://netbsd.gw.com/cgi-bin/man-cgi?reboot+8+NetBSD-5.0.1+i386).
[reboot(8)](http://netbsd.gw.com/cgi-bin/man-cgi?reboot+8+NetBSD-5.0.1+i386)
will not properly run shutdown RC scripts and will not safely disable swap. This
will cause dirty parity at every reboot.

### The first boot with RAID

At this point, temporarily configure your system to boot Disk1/wd1. See notes in
[[Testing Boot Blocks|guide/rf#adding-text-boot]] for details on this process.
The system should boot now and all filesystems should be on the RAID devices.
The RAID will be functional with a single component, however the set is not
fully functional because the bogus drive (wd9) has failed.

    # egrep -i "raid|root" /var/run/dmesg.boot
    raid0: RAID Level 1
    raid0: Components: component0[**FAILED**] /dev/wd1a
    raid0: Total Sectors: 19540864 (9541 MB)
    boot device: raid0
    root on raid0a dumps on raid0b
    root file system type: ffs
    
    # df -h
    Filesystem    Size     Used     Avail Capacity  Mounted on
    /dev/raid0a   8.9G     196M      8.3G     2%    /
    kernfs        1.0K     1.0K        0B   100%    /kern
    
    # swapctl -l
    Device      1K-blocks     Used    Avail Capacity  Priority
    /dev/raid0b    262592        0   262592     0%    0
    # raidctl -s raid0
    Components:
              component0: failed
               /dev/wd1a: optimal
    No spares.
    component0 status is: failed.  Skipping label.
    Component label for /dev/wd1a:
       Row: 0, Column: 1, Num Rows: 1, Num Columns: 2
       Version: 2, Serial Number: 2009122601, Mod Counter: 65
       Clean: No, Status: 0
       sectPerSU: 128, SUsPerPU: 1, SUsPerRU: 1
       Queue size: 100, blocksize: 512, numBlocks: 19540864
       RAID Level: 1
       Autoconfig: Yes
       Root partition: Yes
       Last configured as: raid0
    Parity status: DIRTY
    Reconstruction is 100% complete.
    Parity Re-write is 100% complete.
    Copyback is 100% complete.

### Adding Disk0/wd0 to RAID

We will now add Disk0/wd0 as a component of the RAID. This will destroy the
original file system structure. On i386, the MBR disklabel will be unaffected
(remember we copied wd0's label to wd1 anyway) , therefore there is no need to
"zero" Disk0/wd0. However, we need to relabel Disk0/wd0 to have an identical
NetBSD disklabel layout as Disk1/wd1. Then we add Disk0/wd0 as "hot-spare" to
the RAID set and initiate the parity reconstruction for all RAID devices,
effectively bringing Disk0/wd0 into the RAID-1 set and "syncing up" both disks.

    # disklabel -r wd1 > /tmp/disklabel.wd1
    # disklabel -R -r wd0 /tmp/disklabel.wd1

As a last-minute sanity check, you might want to use
[diff(1)](http://netbsd.gw.com/cgi-bin/man-cgi?diff+1+NetBSD-5.0.1+i386) to
ensure that the disklabels of Disk0/wd0 match Disk1/wd1. You should also backup
these files for reference in the event of an emergency.

    # disklabel -r wd0 > /tmp/disklabel.wd0
    # disklabel -r wd1 > /tmp/disklabel.wd1
    # diff /tmp/disklabel.wd0 /tmp/disklabel.wd1
    # fdisk /dev/rwd0 > /tmp/fdisk.wd0
    # fdisk /dev/rwd1 > /tmp/fdisk.wd1
    # diff /tmp/fdisk.wd0 /tmp/fdisk.wd1
    # mkdir /root/RFbackup
    # cp -p /tmp/{disklabel,fdisk}* /root/RFbackup

Once you are sure, add Disk0/wd0 as a spare component, and start reconstruction:

    # raidctl -v -a /dev/wd0a raid0
    /netbsd: Warning: truncating spare disk /dev/wd0a to 241254528 blocks
    # raidctl -v -s raid0
    Components:
              component0: failed
               /dev/wd1a: optimal
    Spares:
               /dev/wd0a: spare
    [...snip...]
    # raidctl -F component0 raid0
    RECON: initiating reconstruction on col 0 -> spare at col 2
     11% |****                                   | ETA:    04:26 \

Depending on the speed of your hardware, the reconstruction time will vary. You
may wish to watch it on another terminal (note that you can interrupt
`raidctl -S` any time without stopping the synchronisation):

    # raidctl -S raid0
    Reconstruction is 0% complete.
    Parity Re-write is 100% complete.
    Copyback is 100% complete.
    Reconstruction status:
      17% |******                                 | ETA: 03:08 -

After reconstruction, both disks should be *optimal*.

    # tail -f /var/log/messages
    raid0: Reconstruction of disk at col 0 completed
    raid0: Recon time was 1290.625033 seconds, accumulated XOR time was 0 us (0.000000)
    raid0:  (start time 1093407069 sec 145393 usec, end time 1093408359 sec 770426 usec)
    raid0: Total head-sep stall count was 0
    raid0: 305318 recon event waits, 1 recon delays
    raid0: 1093407069060000 max exec ticks
    
    # raidctl -v -s raid0
    Components:
               component0: spared
               /dev/wd1a: optimal
    Spares:
         /dev/wd0a: used_spare
         [...snip...]

When the reconstruction is finished we need to install the boot loader on the
Disk0/wd0. On i386, install the boot loader into `/dev/rwd0a`:

    # /usr/sbin/installboot -o timeout=15 -v /dev/rwd0a /usr/mdec/bootxx_ffsv1
    File system:         /dev/rwd0a
    Primary bootstrap:   /usr/mdec/bootxx_ffsv1
    Boot options:        timeout 15, flags 0, speed 9600, ioaddr 0, console pc

On sparc64:

    # /usr/sbin/installboot -v /dev/rwd0a /usr/mdec/bootblk
    File system:         /dev/rwd0a
    Primary bootstrap:   /usr/mdec/bootblk
    Bootstrap start sector: 1
    Bootstrap byte count:   5140
    Writing bootstrap

And finally, reboot the machine one last time before proceeding. This is
required to migrate Disk0/wd0 from status "used\_spare" as "Component0" to state
"optimal". Refer to notes in the next section regarding verification of clean
parity after each reboot.

    # shutdown -r now

### Testing Boot Blocks

At this point, you need to ensure that your system's hardware can properly boot
using the boot blocks on either disk. On i386, this is a hardware-dependent
process that may be done via your motherboard CMOS/BIOS menu or your controller
card's configuration menu.

On i386, use the menu system on your machine to set the boot device order /
priority to Disk1/wd1 before Disk0/wd0. The examples here depict a generic Award

BIOS.

![Award BIOS i386 Boot Disk1/wd1](/guide/images/raidframe_awardbios2.png)
**Award BIOS i386 Boot Disk1/wd1**

Save changes and exit:

    >> NetBSD/i386 BIOS Boot, Revision 5.2 (from NetBSD 5.0.2)
    >> (builds@b7, Sun Feb 7 00:30:50 UTC 2010)
    >> Memory: 639/130048 k
    Press return to boot now, any other key for boot menu
    booting hd0a:netbsd - starting in 30

You can determine that the BIOS is reading Disk1/wd1 because the timeout of th

boot loader is 30 seconds instead of 15. After the reboot, re-enter the BIOS an
configure the drive boot order back to the default:

![Award BIOS i386 Boot Disk0/wd0](/guide/images/raidframe_awardbios1.png)
**Award BIOS i386 Boot Disk0/wd0**

Save changes and exit:

    >> NetBSD/i386 BIOS Boot, Revision 5.2 (from NetBSD 5.0.2)
    >> Memory: 639/130048 k
    Press return to boot now, any other key for boot menu
    booting hd0a:netbsd - starting in 15

Notice how your custom kernel detects controller/bus/drive assignments
independent of what the BIOS assigns as the boot disk. This is the expected
behavior.

On sparc64, use the Sun OpenBoot **devalias** to confirm that both disks are bootable:

    Sun Ultra 5/10 UPA/PCI (UltraSPARC-IIi 400MHz), No Keyboard
    OpenBoot 3.15, 128 MB memory installed, Serial #nnnnnnnn.
    Ethernet address 8:0:20:a5:d1:3b, Host ID: nnnnnnnn.
    
    ok devalias
    [...snip...]
    cdrom /pci@1f,0/pci@1,1/ide@3/cdrom@2,0:f
    disk /pci@1f,0/pci@1,1/ide@3/disk@0,0
    disk3 /pci@1f,0/pci@1,1/ide@3/disk@3,0
    disk2 /pci@1f,0/pci@1,1/ide@3/disk@2,0
    disk1 /pci@1f,0/pci@1,1/ide@3/disk@1,0
    disk0 /pci@1f,0/pci@1,1/ide@3/disk@0,0
    [...snip...]
    
    ok boot disk0 netbsd
    Initializing Memory [...]
    Boot device /pci/pci/ide@3/disk@0,0 File and args: netbsd
    NetBSD IEEE 1275 Bootblock
    >> NetBSD/sparc64 OpenFirmware Boot, Revision 1.13
    >> (builds@b7.netbsd.org, Wed Jul 29 23:43:42 UTC 2009)
    loadfile: reading header
    elf64_exec: Booting [...]
    symbols @ [....]
     Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
         2006, 2007, 2008, 2009
         The NetBSD Foundation, Inc.  All rights reserved.
     Copyright (c) 1982, 1986, 1989, 1991, 1993
         The Regents of the University of California.  All rights reserved.
    [...snip...]

And the second disk:

    ok boot disk2 netbsd
    Initializing Memory [...]
    Boot device /pci/pci/ide@3/disk@2,0: File and args:netbsd
    NetBSD IEEE 1275 Bootblock
    >> NetBSD/sparc64 OpenFirmware Boot, Revision 1.13
    >> (builds@b7.netbsd.org, Wed Jul 29 23:43:42 UTC 2009)
    loadfile: reading header
    elf64_exec: Booting [...]
    symbols @ [....]
     Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
         2006, 2007, 2008, 2009
         The NetBSD Foundation, Inc.  All rights reserved.
     Copyright (c) 1982, 1986, 1989, 1991, 1993
         The Regents of the University of California.  All rights reserved.
    [...snip...]

At each boot, the following should appear in the NetBSD kernel
[dmesg(8)](http://netbsd.gw.com/cgi-bin/man-cgi?dmesg+8+NetBSD-5.0.1+i386) :

    Kernelized RAIDframe activated
    raid0: RAID Level 1
    raid0: Components: /dev/wd0a /dev/wd1a
    raid0: Total Sectors: 19540864 (9541 MB)
    boot device: raid0
    root on raid0a dumps on raid0b
    root file system type: ffs

Once you are certain that both disks are bootable, verify the RAID parity is
clean after each reboot:

    # raidctl -v -s raid0
    Components:
              /dev/wd0a: optimal
              /dev/wd1a: optimal
    No spares.
    [...snip...]
    Component label for /dev/wd0a:
       Row: 0, Column: 0, Num Rows: 1, Num Columns: 2
       Version: 2, Serial Number: 2009122601, Mod Counter: 67
       Clean: No, Status: 0
       sectPerSU: 128, SUsPerPU: 1, SUsPerRU: 1
       Queue size: 100, blocksize: 512, numBlocks: 19540864
       RAID Level: 1
       Autoconfig: Yes
       Root partition: Yes
       Last configured as: raid0
    Component label for /dev/wd1a:
       Row: 0, Column: 1, Num Rows: 1, Num Columns: 2
       Version: 2, Serial Number: 2009122601, Mod Counter: 67
       Clean: No, Status: 0
       sectPerSU: 128, SUsPerPU: 1, SUsPerRU: 1
       Queue size: 100, blocksize: 512, numBlocks: 19540864
       RAID Level: 1
       Autoconfig: Yes
       Root partition: Yes
       Last configured as: raid0
    Parity status: clean
    Reconstruction is 100% complete.
    Parity Re-write is 100% complete.
    Copyback is 100% complete.


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