BootDegradedRaid
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* '''Packages affected''': mdadm, grub | * '''Packages affected''': mdadm, grub, initramfs, udev, lvm2 |
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This specification defines a methodology for enhancing Ubuntu's boot procedures to configure and support booting a system dependent on a degraded RAID1 device. |
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Ubuntu's installer currently supports installation to software RAID1 targets for /boot and /. When one of the mirrored disks fails, and mdadm marks the RAID ''degraded'', it becomes impossible to reboot the system in an unattended manner. Booting Ubuntu with a failed device in a RAID1 will force the system into a recovery console. In some cases, this is the desired behavior, as a local system administrator would want to backup critical data, cleanly halt the system, and replace the faulty hardware immediately. In other cases, this behavior is highly undesired--particularly when the system administrator is remotely located and would prefer a system with redundant disks tolerate a failed device even on reboot. |
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* Software RAID is often a less expensive alternative to Hardware RAID, and is always available on any Ubuntu system with multiple disk devices * This is particularly useful on low-end and small-form-factor servers without built-in Hardware RAID, such as blades and 1-U rack mount systems * RAID1 (mirroring) is currently a convenient mechanism for providing runtime failover of hard disks in Ubuntu * Remotely administered systems where the owners have taken the initiative to use dedundant disks in a RAID1 configuration expect to be able to boot even after a RAID degradation event |
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== Design == | The scope of this specification is to solve this problem within Ubuntu's software raid support and default bootloader within the Intrepid Ibex development cycle. == Design / Work Items == * '''Bootloader''' * '''MD Error Handling''' * '''Root Filesystem Wait''' |
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* https://blueprints.launchpad.net/ubuntu/+spec/boot-degraded-raid * https://wiki.ubuntu.com/UDS-Intrepid/Report/Server#head-75c995bdf63bb5afe0f08461aba9200b6c95814f * https://lists.ubuntu.com/archives/ubuntu-devel/2007-September/024221.html * http://www.outflux.net/blog/archives/2006/04/23/grub-yaird-mdadm-and-missing-drives/ * wiki:Bug:120375 * wiki:Bug:125471 |
Launchpad Entry: https://blueprints.edge.launchpad.net/ubuntu/+spec/boot-degraded-raid
Created: 2008-05-30
Contributors: DustinKirkland
Packages affected: mdadm, grub, initramfs, udev, lvm2
Summary
This specification defines a methodology for enhancing Ubuntu's boot procedures to configure and support booting a system dependent on a degraded RAID1 device.
Rationale
Ubuntu's installer currently supports installation to software RAID1 targets for /boot and /. When one of the mirrored disks fails, and mdadm marks the RAID degraded, it becomes impossible to reboot the system in an unattended manner.
Booting Ubuntu with a failed device in a RAID1 will force the system into a recovery console.
In some cases, this is the desired behavior, as a local system administrator would want to backup critical data, cleanly halt the system, and replace the faulty hardware immediately.
In other cases, this behavior is highly undesired--particularly when the system administrator is remotely located and would prefer a system with redundant disks tolerate a failed device even on reboot.
Use Cases
- Software RAID is often a less expensive alternative to Hardware RAID, and is always available on any Ubuntu system with multiple disk devices
- This is particularly useful on low-end and small-form-factor servers without built-in Hardware RAID, such as blades and 1-U rack mount systems
- RAID1 (mirroring) is currently a convenient mechanism for providing runtime failover of hard disks in Ubuntu
- Remotely administered systems where the owners have taken the initiative to use dedundant disks in a RAID1 configuration expect to be able to boot even after a RAID degradation event
Scope
The scope of this specification is to solve this problem within Ubuntu's software raid support and default bootloader within the Intrepid Ibex development cycle.
Design / Work Items
Bootloader
MD Error Handling
Root Filesystem Wait
Implementation
Outstanding Issues
BoF agenda and discussion
References
https://blueprints.launchpad.net/ubuntu/+spec/boot-degraded-raid
https://wiki.ubuntu.com/UDS-Intrepid/Report/Server#head-75c995bdf63bb5afe0f08461aba9200b6c95814f
https://lists.ubuntu.com/archives/ubuntu-devel/2007-September/024221.html
http://www.outflux.net/blog/archives/2006/04/23/grub-yaird-mdadm-and-missing-drives/
wiki:120375
wiki:125471
BootDegradedRaid (last edited 2010-04-21 10:02:37 by 188-194-18-172-dynip)