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Revision as of 05:38, 17 March 2017 by Jkurik (talk | contribs) (Release Notes: https://pagure.io/fesco/issue/1688#comment-430734)
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Anaconda LVM RAID

Summary

Use LVM RAID instead of LVM of top of MD RAID in the Anaconda installer.

Owner

Current status

Detailed Description

In the current situation when a user chooses LVM (or Thin LVM) partitioning in the Custom Spoke and then sets RAID level for the VG Anaconda (and Blivet) create an MD RAID device which is used as a PV for the VG. With this change we are going to use LVM RAID directly instead. That means that all the LVs in that VG will be RAID LVs with the specified RAID level. LVM RAID provides same functionality as MD RAID (it shares the same kernel code) with better flexibility and additional features expected in future.

Benefit to Fedora

Using a new promising solution with better flexibility (e.g. using different RAID levels for different LVs, changing RAID levels of existing LVs etc.) and reliability due to ongoing development and maintenance from the LVM team.

Scope

  • Proposal owners:
    • Blivet developers: Support creation of LVM RAID in a similar way as LVM on top of MD RAID. (Creation of RAID LVs is already supported.)
    • Anaconda developers: Use the new way to create LVM RAID instead of creating LVM on top of MD RAID.
    • LVM developers: LVM RAID already has all features required by this change.
  • Other developers: N/A (not a System Wide Change)
  • Release engineering: N/A
  • Policies and guidelines: N/A (not a System Wide Change)
  • Trademark approval: N/A (not needed for this Change)

Upgrade/compatibility impact

N/A (not a System Wide Change)

How To Test

1. Try LVM (or Thin LVM) installation with some RAID level specified for the newly created VG.

2. Reboot.

3. Check that the newly created LVs have the specified RAID level. (e.g. using "sudo lvs -o +lv_layout")

User Experience

There should be no visible change for non-expert users. Expert users could make use of the new LVM RAID's features.

Dependencies

Anaconda (Blivet) already depends on all packages (lvm2) related to this change.

Contingency Plan

  • Contingency mechanism: Revert changes in Anaconda and keep using the existing solution
  • Contingency deadline: Beta (Due to the simple contingency mechanism.)
  • Blocks release: Yes


Documentation

Documentation will be covered in the Installation Guide.

Release Notes

TBD