[LU-19546] Tight binding between erasure code and parity mirrors

• Type: Task
• Resolution: Duplicate
• Priority: Medium
• Severity: 3
• Assignee: Zhenyu Xu
• Reporter: Patrick Farrell

Description

Parity mirrors need to be tightly coupled to the specific data mirror they were created to match; otherwise, they cannot provide proper redundancy. If they are not linked, the stripe allocation will not correspond correctly between data and parity components.

To accomplish this, we must store the mirror ID of the data mirror in each of the corresponding parity components.

We need 16 bits to represent the mirror ID. To accommodate this, we’ve selected the LLC timestamp field, which is currently a 64-bit field that is set and printed but not actually used for functional purposes. We can repurpose the upper 16 bits of this field to store the mirror ID of the data mirror associated with each parity mirror.

Issue Links

• duplicates: LU-19545 FLR-EC: Tight binding between erasure code and parity mirrors