Bug 1394051

Summary: [RFE] LVM RAID: Add RAID 4/5/6 journaling support (raid5-cache)
Product: Red Hat Enterprise Linux 8 Reporter: Jonathan Earl Brassow <jbrassow>
Component: lvm2Assignee: Heinz Mauelshagen <heinzm>
lvm2 sub component: Mirroring and RAID QA Contact: cluster-qe <cluster-qe>
Status: CLOSED WONTFIX Docs Contact:
Severity: unspecified    
Priority: low CC: agk, cmarthal, heinzm, jbrassow, mcsontos, msnitzer, pasik, prajnoha, roland.friedwagner, zkabelac
Version: 8.2Keywords: FutureFeature
Target Milestone: rc   
Target Release: 8.4   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1400194 1482610 (view as bug list) Environment:
Last Closed: 2020-12-01 07:27:37 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1400194, 1430028    
Bug Blocks:    

Description Jonathan Earl Brassow 2016-11-10 22:05:41 UTC
The RAID 4/5/6 kernel module/personality has support for journaling to solve the "write-hole" problem.  This should be added to dm-raid.c/LVM.

Comment 2 Heinz Mauelshagen 2016-11-16 16:19:15 UTC
*** Bug 1394052 has been marked as a duplicate of this bug. ***

Comment 3 Heinz Mauelshagen 2016-11-16 16:50:26 UTC
raid5-cache.c provides 2 major features:
- journal stripes on a dedicated device to address the write hole caused
  by non-atomic updates of N raid disks;
  this obviously introduces latencies, thus slows down raid4/5/6 io
- allow for writeback caching of dirty journal entries in order to
  compensate journalling penalties (upstream 11/10/2016);
  this obviously introduces resilience issues WRT the journal device
  thus requiring resilient types to be used

Comment 5 Heinz Mauelshagen 2016-11-30 16:47:33 UTC
Kepping this bz for the future uspace part of the implementation and cloned
https://bugzilla.redhat.com/show_bug.cgi?id=1400194 for the kernel part.

Comment 9 Heinz Mauelshagen 2017-12-18 16:28:25 UTC
"[RHEL7.5 PATCH v2 00/17] dm raid: update to upstream fixing deadlocks/races"
to rhkernel-list on Dec 13

Comment 11 Jonathan Earl Brassow 2018-01-09 15:56:15 UTC
This bug is for LVM integration, not kernel feature inclusion or updates.  Moving back to ASSIGNED as there will be required LVM changes to make use of the kernel features.

Comment 13 Heinz Mauelshagen 2019-12-05 17:26:00 UTC
Not planning to add to RHEL7.
Moving to RHEL8 which has support for journal device and modes (writeback and writethrough).

Comment 16 RHEL Program Management 2020-12-01 07:27:37 UTC
After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.