Features/AnacondaStorageRewrite

= Anaconda Storage Rewrite =

Summary
Anaconda's storage configuration code is being rewritten from scratch to address several design limitations and replace outdated chunks of code.

Owner

 * Name: Dave Lehman


 * email: dlehman AT fedoraproject DOT org

Current status

 * Targeted release: Fedora 11
 * Last updated: 2009-04-14
 * Percentage of completion: 100%

Detailed Description
The new storage code will use udev for detection of block devices and will also include completely rewritten modules for management of partitions (pyparted), LVM, Software RAID, block device encryption (pycryptsetup).

The rewrite does not include the UI pages for storage configuration due to resource constraints.

See Anaconda/StorageRewrite for further details.

Benefit to Fedora
This rewrite will address a variety of issues in anaconda's current storage configuration code. One of the major limitations of the current design is that it is difficult to introduce support for new storage technologies, which has become clear through our efforts to add support for things like iSCSI and LUKS, among others. The newly redesigned storage management module will create an interface for managing devices of various types through a flexible and extensible framework. This will, in turn, increase both the stability and the flexibility of the Fedora system installer. Another common theme throughout the rewrite is the use of code that is already in use on installed systems, as opposed to customer installer code, wherever possible. This will improve the consistency of the user experience between installation and the post-install environment.

Scope
All of anaconda's code for creating and configuring disk partitions, LVM, mdraid, dmraid, multipath, iSCSI, LUKS devices, and filesystems is being rewritten.

How To Test
Testing will need to be extensive.

We will have to verify the following areas of functionality as a starting point:


 * creation/configuration of filesystems
 * on new partitions
 * on existing partitions
 * on new LVM logical volumes
 * on preexisting LVM logical volumes
 * on new software RAID devices
 * on existing software RAID devices
 * creation of encrypted block devices at various levels in the device stack (partition, PV, LV, mdarray, &c)
 * detection of arbitrarily complex device configurations (luks, mdraid, lvm, &c)
 * management and configuration of existing encrypted block devices
 * automatic partitioning of systems
 * clearing of existing devices/partitions
 * removal of existing devices
 * reconfiguration of existing devices
 * detection of existing upgradable installations with widely varied storage configurations
 * rescue mounting of existing systems with a wide variety of storage configurations

There is more. Unit tests are being developed, and we will plan a Fedora Test Day. Before this code hits Rawhide it will be smoke-tested in a custom compose.

User Experience
This should improve the user's experience with regard to the storage configuration portion of system installation.

Initially, of course, we will severely break the tree.

Dependencies

 * pyparted
 * pycryptsetup
 * libiscsi
 * liblvm

Contingency Plan
Revert to previous codebase.

Documentation
See Anaconda/StorageRewrite for further details.

Release Notes

 * Not applicable because this feature is not user-visible, no release note is required.

Comments and Discussion

 * See Talk:Features/AnacondaStorageRewrite