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小 新页面: {{From|https://help.ubuntu.com/community/Installation/SoftwareRAID}} {{Languages|UbuntuHelp:Installation/SoftwareRAID}} How to install Ubuntu onto a '''''Linux Software RAID''''' system =...
 
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{{From|https://help.ubuntu.com/community/Installation/SoftwareRAID}}
{{From|https://help.ubuntu.com/community/Installation/SoftwareRAID}}
{{Languages|UbuntuHelp:Installation/SoftwareRAID}}
{{Languages|UbuntuHelp:Installation/SoftwareRAID}}
How to install Ubuntu onto a '''''Linux Software RAID''''' system
How to create RAID using '''''Ubuntu Software RAID'''''. Including RAID 0, 1, 5 and 6.
Ubuntu 9.10 provides very easy way to build RAID. You can build a RAID system using Ubuntu user interface, requires no CLI anymore!
Note: Be aware of the fragile state of RAID support in Ubuntu and what it takes to get a reliable raid setup (https://wiki.ubuntu.com/ReliableRaid), but most of them has fixed since Ubuntu 8.10.
=== Introduction ===
=== Introduction ===
RAID mirroring is a method of using two hard-drives to act as one, avoiding the possibility of a catastrophic loss if one of the drives should fail. This method is possible through either software (where the operating system knows about both drives and actively maintains both of them) or through hardware (where a special controller makes the OS think there's only one drive and maintains the drives 'invisibly').
RAID is a method of using multiple hard drives to act as one, there are 2 purpose of RAID:
The RAID software included with current versions of Linux (and Ubuntu) is based on the 'mdadm' driver and works very well, better even than many so-called 'hardware' RAID controllers.
* Expand drive capacity: RAID 0. If you have 2 x 500 GB HDD then total space become 1 TB
NOTE: Many aftermarket motherboards tout 'hardware RAID' but it's really not.  Instead, it's a software driver with a slight hardware 'assist' from the motherboard; these systems are known as "FakeRAID" in the Linux community.  If you're doing a new install, it is better to use the standard Linux drivers.  If you're trying to dual-boot an existing FakeRAID setup, or you're insistent on using it even on a new install, you need to follow these instructions, [[UbuntuHelp:FakeRaidHowto|FakeRaidHowto]].
* Prevent data loss in case of drive failure: RAID 1, RAID 5, and RAID 6. You can combine RAID 0 to other RAID, e.g RAID 0 + 1 become RAID 10.
There are 3 ways to create RAID:
<ol><li>Software-RAID: Where the RAID created by software.
</li><li>Hardware-RAID: A special controller used to build RAID. RAID hardware faster, no CPU overload and can be used for any OS
</li><li>FakeRAID: Since RAID hardware is very expensive, many motherboard manufacturers use multi-channel controllers with special BIOS features to perform RAID. This implementation is faster than software RAID. Read [[UbuntuHelp:FakeRaidHowto|FakeRaidHowto]] for details.</li></ol>
 
The RAID software included with current versions of Linux (and Ubuntu) is based on the 'mdadm' driver and works very well.
=== Requirements ===
=== Requirements ===
* The "Alternate" install CD for *buntu. [[UbuntuHelp:GettingUbuntu#head-40b5bcdbc1d4ec7b8149519dfd4f08c7fa274559| Getting Ubuntu Alternate Install disk]]
* If you're building a server, the server install CD includes the necessary options.
* At least two hard drives, preferably the same mode, size etc..
* If you're building a desktop then you need the "Alternate" install CD for Ubuntu. Read [[UbuntuHelp:GettingUbuntu#head-40b5bcdbc1d4ec7b8149519dfd4f08c7fa274559| Getting Ubuntu Alternate Install disk]] and [[UbuntuHelp:Installation#head-194b248381c71c37f7b187c6b814bbe7e31d91d6| How to do a Ubuntu Alternate Install]]
* [[UbuntuHelp:BurningIsoHowto|How to Burn an ISO]]
* At least 2 hard drives, preferably same size
After a successful install, you should also manually fix 2 shortcomings in the default configuration:
After a successful install, you should also manually fix 2 shortcomings in the default configuration:
* Install GRUB boot-loader on second drive
* Install GRUB boot-loader on second drive (this step is not need if you use Ubuntu 9.10)
* Update startup script to detect a failed drive
* Update startup script to detect a failed drive
=== Installing ===
=== Installing ===
[[UbuntuHelp:BurningIsoHowto|How to Burn an ISO]]
Install Ubuntu until you get to partitioning the disks
Follow the install instruction for an Alternate Install until you get to partitioning the disks
https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_00.png
[[UbuntuHelp:Installation#head-194b248381c71c37f7b187c6b814bbe7e31d91d6| How to do a Ubuntu Alternate Install]]
==== Partitioning the disk ====
==== Partitioning the disk ====
For a standard 2 hard drive system in RAID1 Configuration. (repeat steps for additional Hard drives)
'''Warning: the /boot filesystem cannot use any softRAID level other than 1''' with the stock Ubuntu bootloader.  If you want to use some other RAID level for most things, you'll need to create separate partitions and make a RAID1 device for /boot.
'''Warning this will remove all data on hard drives''' See [[UbuntuHelp:DrivesAndPartitions|DrivesAndPartitions]] for more information.
'''Warning: this will remove all data on hard drives.'''  
<ol><li>Select "Manual" as your partition method.
1. Select "Manual" as your partition method  
</li><li>Select your 1st hard drive, and agree to "Create a new empty partition table on this device ?"
 
</li><li>Repeat step 2 with your 2nd hard drive.
https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_01.png
</li><li>Select the "FREE SPACE" on the 1st drive then select "Create a new partition"
2. Select your hard drive, and agree to "Create a new empty partition table on this device ?"  
</li><li>Select the size (suggestion, normally you want a root partition major part of the hard drive and swap which is 1.5 times the amount of ram )
 
</li><li>Select Primary, then Beginning.
https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_02.png https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_03.png
</li><li>Select the "Use as:" by default this is "Ext3 journalling file system" we want to change that to "physical volume for RAID"
3. Select the "FREE SPACE" on the 1st drive then select "automatically partition the free space
</li><li>Select if the partition is the main "/" partition select "bootable flag" and set it to "on"
 
</li><li>Select "Done setting up the partition"</li></ol>
https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_04.png https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_05.png
4. Ubuntu will create 2 partitions: / and swap, as shown below:  
 
https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_06.png
5. On / partition select "bootable flag" and set it to "on"
 
https://help.ubuntu.com/community/Installation/SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_06.png
6. Repeat steps 2 to 5 for the other hard drive


10. Repeat steps 4 to 10 for the 2nd hard drive and the other partitions.
As you see Ubuntu 9.10 makes RAID creation very easy. No need to define partition manually anymore! Ubuntu 9.10 also use ext4 the latest Linux file system.
==== Configuring the RAID ====
==== Configuring the RAID ====
<ol><li>Once you have complete your partitioning in the main "Partition Disks" page select "Configure Software RAID"
<ol><li>Once you have complete your partitioning in the main "Partition Disks" page select "Configure Software RAID"
</li><li>Select "Yes"
</li><li>Select "Yes"
</li><li>Select "Create new MD drive"
</li><li>Select "Create new MD drive"
</li><li>Select RAID1, or type of RAID you want (RAID0 RAID1 RAID5)
</li><li>Select RAID type: RAID 0, RAID 1, RAID 5 or RAID 6
</li><li>Number of devices 2 or the amount of hard drives you have
</li><li>Number of devices. RAID 0 and 1 need 2 drives. 3 for RAID 5 and 4 for RAID 6.
</li><li>Number of spare devices 0
</li><li>Number of spare devices. Enter 0 if you have no spare drive.
</li><li>select which partitions to use.</li></ol>
</li><li>select which partitions to use. Generally they will be sda1 and sdb1 or hda1 or hdb1. Generally the numbers will match and the different letters are for different hard drives.
 
</li><li>At this point the installation may become unresponsive this is the hard drives already syncing. Repeat steps 3 to 7 with each pair of partitions you have created.
generally they will be sda1 and sdb1 or hda1 or hdb1 generally the numbers will match and the different letters are for different hard drives
</li><li>Once done, select finish.</li></ol>
{i} at this point the installation may become unresponsive this is the hard drives already syncing, time for a food break.
<ol><li>Repeat steps 3 to 7 with each pair of partitions you have created.
</li><li>once done select finish.</li></ol>


==== Formatting ====
==== Formatting ====
You now have a list of your hard drives and your RAID drives. We will now format and set the mount point for other RAID drives. Treat the RAID drive as a local hard drive and format and mount accordingly
Ubuntu 9.10 will automatically format your partitions.
<ol><li>Select Partition.
==== Boot Loader ====
</li><li>Go to Use as Select Ext 3 for your normal partitions or swap area for your swap partition
There are several problems reported by previous version of Ubuntu. But Ubuntu 9.10 already fixes them. In case you next HDD won't boot then simply install Grub there.
</li><li>If you select Ext 3 then select your mount point if you only have one partition for ext 3 select /
#grub-install /dev/sdb
</li><li>Repeat for each RAID partition</li></ol>
#grub-install /dev/sdc
==== Boot from Degraded Disk ====
If default HDD fail then RAID will ask you to boot from degraded disk. In best practice, as specially if you put your server on remote area then you may make this automatically.
Since Ubuntu 8.10 there is a new feature to boot automatically if default RAID disk fail. Simply:
<ol><li>edit this file /etc/initramfs-tools/conf.d/mdadm
</li><li>change "BOOT_DEGRADED=false" to "BOOT_DEGRADED=true"</li></ol>


Select "Finish partitioning and write changes to disk"
NB:
==== Notes ====
* Additionally, this can be specified on the kernel boot line with the bootdegraded=[true|false]
Installation continues as normal.
* You also can use #dpkg-reconfigure mdadm rather than CLI!
From this point in your hard drive lights will probably be on continuously this is the hard drives syncing up, it's probably best just leaving your computer alone waiting for the RAID to sync then to continue with the installation.
Now, you have completed the step of making RAID in a few minutes!
=== Adding GRUB to 2nd drive ===
=== Test your RAID now! ===
Known problems with GRUB and RAID configurations in anything but RAID1
The very importing part of RAID building is ... TESTING if your RAID works! Simply follow these step to test your RAID:
GRUB should be installed on all hard drives.
<ol><li>shutdown your server
If your drives are /sda and /sdb, the first drive will automatically be configured with GRUB but the second drive will not.  To add it:
</li><li>remove the power and cable data of your first drive
<pre><nowiki>
</li><li>start your server, see if your server can boot from degraded disk!</li></ol>
> sudo grub
grub> device (hd1) /dev/sdb
grub> root (hd1,0)
grub> setup (hd1)
grub> quit</nowiki></pre>
=== Updating startup script ===
Everytime the computer boots-up it scans the available hard-drives to try and identify any RAID array.  Most of the time this is easy and takes place instantaneously.  If one of the drives is unusable, however, then the computer needs to operate the remaining drive in 'degraded' mode.  If the bad drive failed during regular operation, then the computer will have already removed it from the configuration of the array.  If the drive had previously been working, however, and failed spontaneously during power-up or boot-up, then the computer needs to figure it out on-the-fly.
The script which tries to detect a failed drive is called 'initramfs' and, as of Ubuntu 8.04, the default code in this script completely fails.  The procedure below adds an additional step so that it will succeed.
1. Update the 'initramfs' boot script,


<pre><nowiki>
> gksudo gedit /usr/share/initramfs-tools/scripts/local</nowiki></pre>
2. Find the comment,
<pre><nowiki>
# We've given up, but we'll let the user fix matters if they can".</nowiki></pre>
3. Just *before* this comment, add the following:
<pre><nowiki>
# The following code was added to allow degraded RAID arrays to start
if [ ! -e "${ROOT}" ] || ! /lib/udev/vol_id "${ROOT}" >/dev/null 2>&1; then
# Try mdadm and allow degraded arrays to start in case a drive has failed
log_begin_msg "Attempting to start RAID arrays and allow degraded arrays"
/sbin/mdadm --assemble --scan
log_end_msg
fi</nowiki></pre>
4. Save the change and exit the editor.
5. Finally, update the boot image to use the updated script,
<pre><nowiki>
> sudo update-initramfs -u</nowiki></pre>
=== Troubleshooting ===
=== Troubleshooting ===
'''Swap space doesn't come up, error message in dmesg'''
==== Swap space doesn't come up, error message in dmesg ====
Provided the RAID is working fine this can be fixed with
Provided the RAID is working fine this can be fixed with
<pre><nowiki>
* sudo update-initramfs -k all -u
> sudo update-initramfs -k all -u</nowiki></pre>
=== Resources ===
http://ubuntuforums.org/showthread.php?t=408461
http://man-wiki.net/index.php/8:mdadm
=== Using mdadm ===
=== Using mdadm ===
==== Checking the status of your RAID ====
==== Checking the status of your RAID ====
2 useful commands to check the status are:
Two useful commands to check the status are:
<pre><nowiki>
* cat /proc/mdstat  
cat /proc/mdstat </nowiki></pre>
This will show output something similar to
<pre><nowiki>
Personalities : [raid1] [raid6] [raid5] [raid4]
sudo mdadm --query --detail /dev/md* </nowiki></pre>
md5 : active raid1 sda7[0] sdb7[1]
62685504 blocks [2/2] [UU]
md0 : active raid1 sda1[0] sdb1[1]
256896 blocks [2/2] [UU]
md6 : active raid5 sdc1[0] sde1[2] sdd1[1]
976767872 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
From this information you can see that the available personalities on this machine are "raid1, raid6, raid4, and raid5" which means this machine is setup to use raid devices configured in a raid1, raid6, raid4 and raid5 configuration.
You can also see in the three example meta devices that there are two raid 1 mirrored meta devices. These are md0 and md5. You can see that md5 is a raid1 array and made up of disk /dev/sda partition 7, and /dev/sdb partition 7, containing 62685504 blocks, with 2 out of 2 disks available and both in sync.
The same can be said of md0 only it is smaller (you can see from the blocks parameter) and is made up of /dev/sda1 and /dev/sdb1.
md6 is different in that we can see it is a raid 5 array, striped across 3 disks. These are /dev/sdc1, /dev/sde1 and /dev/sdd1, with a 64k "chunk" size which is basically a "write" size. Algorithm 2 shows it is a write algorithm patern 2 which is "left disk to right disk" writing across the array. You can see that all 3 disks are present and in sync.
* sudo mdadm --query --detail /dev/md*  
( where * is the partition number)
( where * is the partition number)
-----
==== Disk Array Operation ====
[[category:CategoryDocumentation]]
Note: You can add, remove disks or set them as faulty without stopping an array.
1. To stop an array, type:
 
* $ sudo mdadm --stop /dev/md0
* Where /dev/md0 is the array device.
2. Remove a Disk from an Array
 
* $ sudo mdadm --remove /dev/md0 /dev/sda1
* Where /dev/md0 is the array device and /dev/sda is the faulty disk.
3. Add a Disk to an Array
 
* $ sudo mdadm --add /dev/md0 /dev/sda1
* Where /dev/md0 is the array device and /dev/sda is the new disk.
* Note: This is not the same as "growing" the array!
4.Start an Array, to reassemble (start) an array that was previously created:
* $ mdadm --assemble --scan
* mdadm will scan for defined arrays and start assembling it. Use this to track its status:
* $ cat /proc/mdstat
=== Resources ===
* http://ubuntuforums.org/showthread.php?t=408461
* http://man-wiki.net/index.php/8:mdadm
* https://wiki.ubuntu.com/HotplugRaid Keeping your data synced and mirrored on external drives.
* http://en.wikipedia.org/wiki/RAID
* http://en.wikipedia.org/wiki/Mdadm
Thanks to Ubuntu 9.10 team which makes the RAID building very easy.


[[category:UbuntuHelp]]
[[category:UbuntuHelp]]

2010年5月19日 (三) 22:51的最新版本

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How to create RAID using Ubuntu Software RAID. Including RAID 0, 1, 5 and 6. Ubuntu 9.10 provides very easy way to build RAID. You can build a RAID system using Ubuntu user interface, requires no CLI anymore! Note: Be aware of the fragile state of RAID support in Ubuntu and what it takes to get a reliable raid setup (https://wiki.ubuntu.com/ReliableRaid), but most of them has fixed since Ubuntu 8.10.

Introduction

RAID is a method of using multiple hard drives to act as one, there are 2 purpose of RAID:

  • Expand drive capacity: RAID 0. If you have 2 x 500 GB HDD then total space become 1 TB
  • Prevent data loss in case of drive failure: RAID 1, RAID 5, and RAID 6. You can combine RAID 0 to other RAID, e.g RAID 0 + 1 become RAID 10.

There are 3 ways to create RAID:

  1. Software-RAID: Where the RAID created by software.
  2. Hardware-RAID: A special controller used to build RAID. RAID hardware faster, no CPU overload and can be used for any OS
  3. FakeRAID: Since RAID hardware is very expensive, many motherboard manufacturers use multi-channel controllers with special BIOS features to perform RAID. This implementation is faster than software RAID. Read FakeRaidHowto for details.

The RAID software included with current versions of Linux (and Ubuntu) is based on the 'mdadm' driver and works very well.

Requirements

After a successful install, you should also manually fix 2 shortcomings in the default configuration:

  • Install GRUB boot-loader on second drive (this step is not need if you use Ubuntu 9.10)
  • Update startup script to detect a failed drive

Installing

Install Ubuntu until you get to partitioning the disks SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_00.png

Partitioning the disk

Warning: the /boot filesystem cannot use any softRAID level other than 1 with the stock Ubuntu bootloader. If you want to use some other RAID level for most things, you'll need to create separate partitions and make a RAID1 device for /boot. Warning: this will remove all data on hard drives. 1. Select "Manual" as your partition method

SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_01.png 2. Select your hard drive, and agree to "Create a new empty partition table on this device ?"

SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_02.png SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_03.png 3. Select the "FREE SPACE" on the 1st drive then select "automatically partition the free space

SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_04.png SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_05.png 4. Ubuntu will create 2 partitions: / and swap, as shown below:

SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_06.png 5. On / partition select "bootable flag" and set it to "on"

SoftwareRAID?action=AttachFile&do=get&target=ubuntu_raid_06.png 6. Repeat steps 2 to 5 for the other hard drive

As you see Ubuntu 9.10 makes RAID creation very easy. No need to define partition manually anymore! Ubuntu 9.10 also use ext4 the latest Linux file system.

Configuring the RAID

  1. Once you have complete your partitioning in the main "Partition Disks" page select "Configure Software RAID"
  2. Select "Yes"
  3. Select "Create new MD drive"
  4. Select RAID type: RAID 0, RAID 1, RAID 5 or RAID 6
  5. Number of devices. RAID 0 and 1 need 2 drives. 3 for RAID 5 and 4 for RAID 6.
  6. Number of spare devices. Enter 0 if you have no spare drive.
  7. select which partitions to use. Generally they will be sda1 and sdb1 or hda1 or hdb1. Generally the numbers will match and the different letters are for different hard drives.
  8. At this point the installation may become unresponsive this is the hard drives already syncing. Repeat steps 3 to 7 with each pair of partitions you have created.
  9. Once done, select finish.

Formatting

Ubuntu 9.10 will automatically format your partitions.

Boot Loader

There are several problems reported by previous version of Ubuntu. But Ubuntu 9.10 already fixes them. In case you next HDD won't boot then simply install Grub there.

  1. grub-install /dev/sdb
  2. grub-install /dev/sdc

Boot from Degraded Disk

If default HDD fail then RAID will ask you to boot from degraded disk. In best practice, as specially if you put your server on remote area then you may make this automatically. Since Ubuntu 8.10 there is a new feature to boot automatically if default RAID disk fail. Simply:

  1. edit this file /etc/initramfs-tools/conf.d/mdadm
  2. change "BOOT_DEGRADED=false" to "BOOT_DEGRADED=true"

NB:

  • Additionally, this can be specified on the kernel boot line with the bootdegraded=[true|false]
  • You also can use #dpkg-reconfigure mdadm rather than CLI!

Now, you have completed the step of making RAID in a few minutes!

Test your RAID now!

The very importing part of RAID building is ... TESTING if your RAID works! Simply follow these step to test your RAID:

  1. shutdown your server
  2. remove the power and cable data of your first drive
  3. start your server, see if your server can boot from degraded disk!

Troubleshooting

Swap space doesn't come up, error message in dmesg

Provided the RAID is working fine this can be fixed with

  • sudo update-initramfs -k all -u

Using mdadm

Checking the status of your RAID

Two useful commands to check the status are:

  • cat /proc/mdstat

This will show output something similar to Personalities : [raid1] [raid6] [raid5] [raid4] md5 : active raid1 sda7[0] sdb7[1] 62685504 blocks [2/2] [UU] md0 : active raid1 sda1[0] sdb1[1] 256896 blocks [2/2] [UU] md6 : active raid5 sdc1[0] sde1[2] sdd1[1] 976767872 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU] From this information you can see that the available personalities on this machine are "raid1, raid6, raid4, and raid5" which means this machine is setup to use raid devices configured in a raid1, raid6, raid4 and raid5 configuration. You can also see in the three example meta devices that there are two raid 1 mirrored meta devices. These are md0 and md5. You can see that md5 is a raid1 array and made up of disk /dev/sda partition 7, and /dev/sdb partition 7, containing 62685504 blocks, with 2 out of 2 disks available and both in sync. The same can be said of md0 only it is smaller (you can see from the blocks parameter) and is made up of /dev/sda1 and /dev/sdb1. md6 is different in that we can see it is a raid 5 array, striped across 3 disks. These are /dev/sdc1, /dev/sde1 and /dev/sdd1, with a 64k "chunk" size which is basically a "write" size. Algorithm 2 shows it is a write algorithm patern 2 which is "left disk to right disk" writing across the array. You can see that all 3 disks are present and in sync.

  • sudo mdadm --query --detail /dev/md*

( where * is the partition number)

Disk Array Operation

Note: You can add, remove disks or set them as faulty without stopping an array. 1. To stop an array, type:

  • $ sudo mdadm --stop /dev/md0
  • Where /dev/md0 is the array device.

2. Remove a Disk from an Array

  • $ sudo mdadm --remove /dev/md0 /dev/sda1
  • Where /dev/md0 is the array device and /dev/sda is the faulty disk.

3. Add a Disk to an Array

  • $ sudo mdadm --add /dev/md0 /dev/sda1
  • Where /dev/md0 is the array device and /dev/sda is the new disk.
  • Note: This is not the same as "growing" the array!

4.Start an Array, to reassemble (start) an array that was previously created:

  • $ mdadm --assemble --scan
  • mdadm will scan for defined arrays and start assembling it. Use this to track its status:
  • $ cat /proc/mdstat

Resources

Thanks to Ubuntu 9.10 team which makes the RAID building very easy.

取自“https://wiki.ubuntu.org.cn/index.php?title=特殊:Badtitle/NS100:Installation/SoftwareRAID&oldid=138963”