Ubuntu 10.10 desktop RAID 1

RAID on Ubuntu desktop is a pain. The Ubuntu alternate edition makes desktop RAID easy. Build yourself a reliable desktop computer using RAID 1.

My test machine has the Ubuntu system installed in a solid state disk for speed. I added two disks for extensive data stored reliably using a RAID 1 array. The result will have the home directories stored on the RAID array.

We will install Ubuntu the same as described in Ubuntu 10.10 desktop installation using the Ubuntu 10.10 alternate edition and we will perform some extra steps when creating the disk partitions. If you do not want RAID then follow the desktop installation.

You need some disks. RAID needs a minimum of 2 disks for RAID 1 and 3 disks for RAID 5. I can fit 2 disks in the small quiet case I am using for this installation. A third disk, the SSD for the system files, is smaller and can slip in the spot that was used for floppy disks.

You can use more if they will fit in your computer case. The RAID size will be set by the smallest disk and the speed by the slowest disk. Use a set of disks all the same size and speed. I am using 2 TB disks and will end up with a 2 TB partition in the RAID array.

Hardware

We are using a small quiet computer with an SSD (Solid State Disk. See Fastest processing in a small case) for the system disk and two regular disks for space.

BIOS settings

SATA mode: AHCI.
Boot order: CDROM, hard disk

Disk partitioning

You can tell Ubuntu to wipe all the partitions on a disk then create a default configuration but the Ubuntu desktop will not always do that if there are existing partitions from Linux or Unix. At the start up menu, there is an option to Try Ubuntu without installing. You can use that option to partition your disks then save the partitions and quickly return to the installation process. I sometimes delete all the partitions then create one big one covering the whole disk then proceed for a short while then reboot and start again. This forces Ubuntu to delete the existing partition and create the default layout.

The Ubuntu alternate edition appears to follow your disk partition instructions exactly so long as you make some change from the previous configuration.

Startup

Insert the CD. Start your computer. Change the BIOS settings to boot from CD. Boot from CD. You do not get the option of the automated startup presented in the desktop installation. You will be asked to select your language then you see the installation options menu.

The menu entries are:

• Install Ubuntu
• Check disc for defects
• Test memory
• Boot from first hard disk
• Rescue a broken system

When you first use a CD, use the Check disc option. Select Check disc for defects. Ubuntu will read all the files on the disk making sure each file matches a list of sizes and content summaries. Occasionally this test highlights a download error or disk write error you might not find until the end of a long installation process. I normally test the disks on first use and mark them as tested. After the test you press any key to reboot.

The Ubuntu 10.10 alternate edition says it cannot mount the CD-ROM and asks if you want to try again. Answer No. The test works despite the error message.

Install Ubuntu

Select Install Ubuntu.

Choose language

Choose your language for the installation then press [Enter].

Choose a country, territory or area

Choose your country then press [Enter].

Detect keyboard layout

Choose No then press [Enter].

Origin of the keyboard

Choose the keyboard origin then press [Enter].

Keyboard layout

Choose the keyboard layout then press [Enter].

Configure the network

If your computer is connected to a secure network and is not listed as an acceptable device, network detection will fail. My test machine was added to the network in a previous installation and the computer's MAC address is in the router. If MAC or router are meaningless to you, talk to your network administrator.

Please enter the hostname for this system

Type in a simple name, no fancy characters, and it will be used when listing the computers on the networ. You can easily change the name at any time using one of the administration applications. Press [Enter].

h3>Configure the clock

Ubuntu will list a time zone based on mass of information already known about you by every spy on the Internet. Choose Yes then press [Enter].

Partition disks

Choose Manual then press [Enter].

You see a list of partitions. One by one, select each partition, press [Enter], choose Delete the partition then press [Enter].

Select the free space on the SSD, press [Enter], choose Create a new partition then press [Enter]. Set the New partition size to 100MB then press [Enter]. Set the Type for the new partition to Primary then press [Enter]. Set the Location for for the new partition to Beginning then press [Enter]. Enter the following settings then press [Enter].
Use as: Ext4
Mount point: /boot
Mount options: noatime
Label: boot
Select Done setting up the partition then press [Enter].

We should be able to set the boot partition to Bootable flag: on but the Ubuntu alternate edition does not understand that request at this point.

Select the free space on the SSD, press [Enter], choose Create a new partition then press [Enter]. Set the New partition size to 8GB then press [Enter]. Set the Type for the new partition to Primary then press [Enter]. Set the Location for for the new partition to End then press [Enter]. Enter the following settings then press [Enter].
Use as: swap area
Select Done setting up the partition then press [Enter].

Select the free space on the SSD, press [Enter], choose Create a new partition then press [Enter]. Leave the New partition size at the default of all the rest of the disk then press [Enter]. Set the Type for the new partition to Primary then press [Enter]. Set the Location for for the new partition to Beginning then press [Enter]. Enter the following settings then press [Enter].
Use as: Ext4
Mount point: /
Mount options: noatime
Label: system
Select Done setting up the partition then press [Enter].

Select Configure software RAID then press [Enter].

You are asked Write the changes to the storage devices and configure RAID?.

Select Yes then press [Enter].

Select Create MD device then press [Enter].

Select RAID1 then press [Enter].

At Number of active devices for the RAID1 array, enter 2 then press [Enter].

At Number of spare devices for the RAID1 array, enter 0 then press [Enter].

At Active devices for the RAID1 array, select the two free spaces then press [Enter].

Select Yes then press [Enter].

You end up back at the Software configuration actions page. Select Finish then press [Enter].

You are now back at the partition list. There is now a RAID1 device with an empty partition. On my disks there is also a small unused area. Select the 2TB RAID space then press [Enter].

Set the RAID partition to the following settings then press [Enter].
Use as: Ext4
Mount point: /home
Mount options: noatime
Label: home
Select Done setting up the partition then press [Enter].

Select Finish partitioning and write changes to disk then press [Enter].

You are asked the same question again. Select Yes then press [Enter].

This part takes several minutes for 2 TB disks, long enough to make a chilli pizza or iron some shirts or strip down, clean, and assemble a Nikon Speedlight underwater housing.

Set up users and passwords

Full name for the new user: Peter [Enter]
User name for your account: peter [Enter]
Choose a password for the new user: dsfg6789x786 [Enter]
Re-enter password to verify: dsfg6789x786 [Enter]
Encrypt your home directory? yes [Enter]

HTTP proxy information

This is usually blank. Press [Enter].

Install the GRUB boot loader to the master boot record?

Select Yes then press [Enter].

Is the system clock set to UTC?

Select Yes then press [Enter].

Installation Complete

Remove the CD then press [Enter].

BIOS change

At some later point you switch off the computer, remove the USB CDROM drive if you used a USB drive, then change the BIOS to not boot from CD.

Encryption passphrase

The first time an application tries to write to your home directory, you will be prompted to record your encryption passphrase. Choose [Run this action now] to see your passphrase. A terminal screen appears. You type in your password at the Passphrase: prompt. You will see a long string of letters and numbers. Write it down somewhere safe.

Updates

Ubuntu is released every 6 months. You download 670 MB as part of the release. You then apply a lot of changes to catch up. Ubuntu 10.10 was 3 months old when I started this installation and the update download was 210 MB, about 10 percent changed per month.

Select System, Administration, Update Manager to push the updates through. At the end of the update you have to select [Restart Now] to finish the update.

While the updates are downloading, you can start customising Ubuntu.

Synchronisation

A 2TB RAID 1 array can take hours to synchronise the two disks. You would think that starting from two empty partitions they would not need a sync. No, they still sync. You would think a file system would know that most of a partition is empty. No, the sync program is not smart enough to know which parts of a file system are full and which parts are empty.

After more than two hours of syncing, the array is little over half finished. The whole process will take close to five hours. When you have to replace a broken disk, you are faced with the same delay.

Customisation

Power Management

Select System, Preferences, Power Management to stop the screen shutting down while on mains power. Change Display to never sleep then select Make Default. You will have to enter your password in the authentication screen. Select Close to leave the power management screen. You can make this change while the updates are downloading.

Unfortunately the screen saver has only one setting. You cannot set it one way for full power and another way for battery operation. I often switch the screen saver off for desktop computers because it is annoying and not doing anything.

Desktop background

Get rid of that distracting swirly Star Trek style background. Select System, Preferences, Appearance.

The first tab is Theme. Change the desktop background first then return to the theme tab. Select Background tab. Select the plain purple background at the top left then select the little purple colour icon under the pictures then select a colour of your choice in the Pick a Color pop up page. I made the background white (#ffffff).

Select the Theme tab. The default theme is Ambiance with lovely styling but grey on grey text in some places. Clearlooks has black on white text for easier reading on low contrast LCD screens and in sunlight. Radiance is another theme to consider for some screens.

Select the Customise button under the themes. Select the Colors tab in the Customise Theme page. Select the colour button in the Background column next to Selected items:.

I changed the colour to #00ff33 to match the green highlights on an Acer netbook I am testing at the same time.

The background and theme change for you when logged in but not for the Ubuntu log in screen.

Wireless connection

Netbooks and notebooks have wireless connections. I tried a few wireless cards in desktops and they rarely reach wired speeds. The metal case of desktops kills the wireless signal. You can use a USB connected wireless adaptor and place the wireless adaptor away from the metal case.

Select System, Preferences, Network Connections to set up the Wireless connection if you have one. Select the Wireless tab then Add. Give your connection a name, usually the same as the network name or SSID.

Select Connect automatically for one or more wireless networks. You might set one for home and one for work.

The SSID is the id of the network. Some networks broadcast the SSID while others do not.

Select a mode of Infrastucture for use with a router. The alternative, Ad-hoc, lets two computers talk direct without connecting through a network.

Select the Wireless Security tab then set the security level to WPA & WPA2 Personal. You then have to enter your password (also called a passphrase).

Select Available to all users then Apply. Give the software a few seconds to connect. You can then test the connection by removing the wired network cable and browsing the Internet. Test the automatic wireless connection by restarting Ubuntu.

Tests

You can select System, Administration, then System Testing to test Linux on your computer. You see a long list of tests. Switch off those you do not need. You can also skip individual tests during the testing process.

Disk usage

Select System, Administration, then Disk Utility. You should see the single 60 GB partition promised during the installation. Instead you see a 58 GB regular partition then a 2.5 GB swap partition. To make things worse by unnecessary complication, the swap partition is in an extended partition instead of a primary partition. The Linux distribution builders have some really weird ideas and, when you ask them for the logic behind their choices, they often cannot supply an answer because they are just copying what someone else did without passing on a logical reason.

Next select Applications, Accessories, then Disk Usage Analyser. The Disk Usage Analyser says the total capacity of the file system in the 58 GB partition is 52.7 GB, a loss of 5.3 GB to the file system. 3.3 GB, or 6.2% of the available capacity, is used by the current installation.

You can delete and add applications using the Ubuntu Software Center. I deleted Evolution because I use Thunderbird. You can then refresh the disk usage page to see the difference. In the case of Evolution, very little changed because Evolution installs a lot of little bits and only the basic bits are deleted when you delete Evolution. You can then run the Computer Janitor to delete more unused stuff and you start to see a difference.

Power management

Test suspend and resume.

Cleanup

You install and delete applications by selecting Applications then Ubuntu Software Center. You can then select programs by category or through a search.

After deleting the applications, select System, Administration, then Computer Janitor to clean out anything unused. The Janitor selected 90 MB of unused files to delete, files that were used for something but not any more. Collectively you can save about a gigabyte of space by deleting unused applications then cleaning up the related files.

Conclusion

The Ubuntu alternate edition is initially more work than the desktop edition but is the better choice when you want RAID.