Anaconda/Features/MDRaid

= Anaconda use mdraid for certain BIOS-RAID types =

Summary
Use mdraid instead of dmraid for certain BIOS-RAID types (currently only Intel BIOS-RAID using imsm meta-data).

Owner

 * Name: Hans De Goede
 * email: jwrdegoede AT fedoraproject DOT org

Current status

 * Targeted release: Fedora 12
 * Last updated: 2009-07-16
 * Percentage of completion: 100%

Detailed Description
Anaconda will use mdraid instead of dmraid to get access to BIOS-RAID sets using the imsm metadata format. Supporting imsm Raid 0, 1, 5, and 10 sets.

Benefit to Fedora
mdraid offers a number of features over dmraid, and mdraid is where all future development for Intel BIOS-RAID will happen, the most direct visible benefit is support for raid5 sets.

Scope
The code is all written and has passed preliminary testing

How To Test
Testing will require Intel BIOS-RAId capable hardware.

We will have to verify the following areas of functionality:


 * recognize Raid 0,1, 5, 6, 10 devices and install correctly
 * on new partitions
 * on existing partitions
 * on new LVM logical volumes
 * on preexisting LVM logical volumes
 * automatic partitioning of systems
 * clearing of existing devices/partitions
 * boot successfully after install
 * grub needs to be installed correctly
 * dracut needs to handle imsm metadata raid sets correctly
 * detection of existing upgradable installations with widely varied storage configurations
 * rescue mounting of existing systems with a wide variety of storage configurations

User Experience
No impact unless you have this hardware but current users of Intel ISW hardware and dmraid will find their device names changed.

Dependencies

 * mdadm 3.0 final (in rawhide now)

Contingency Plan
Fall back to using dmraid for imsm metadata, the dmraid code will be kept around for handling other metadata formats.

Documentation

 * FIXME: Will need to include in Installation Guide.

Release Notes
Fedora 12 now uses mdraid instead of dmraid for installation onto Intel BIOS-RAID sets, which should be detected automatically. Devices with Intel ISW metadata will be recognized as mdraid NOT dmraid after this change, which will cause them to have different device node names.

This means that special precautions must be taken when upgrading systems with Intel BIOS-RAID sets, by default Fedora does not refer to these device by their device node name, but uses UUID, so default installations can be upgraded without problems.

Before upgrading installations with local modifications to /etc/fstab or /etc/crypttab, or to other configurationfiles which refer to device node names, the affected files need to be manually edited to refer to the devices by UUID instead of by device node path, see the output of the "blkid" command for the UUID's for your devices.

Note this feature is not enabled on livecd's, livecd's will still use dmraid for accessing Intel BIOS RAID sets, as will installations done from livecd's.

Comments and Discussion

 * See Talk:Features/AnacondaStorageRewrite for conversation without bogging down the main feature page