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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.
*** Bug 1394052 has been marked as a duplicate of this bug. ***
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
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.
"[RHEL7.5 PATCH v2 00/17] dm raid: update to upstream fixing deadlocks/races" to rhkernel-list on Dec 13
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.
Not planning to add to RHEL7. Moving to RHEL8 which has support for journal device and modes (writeback and writethrough).
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.