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HAMMER Media Layout – Zone & Freemap
8M BLOCK (262144x32)
LAYER1
8M BLOCK (524288x16)
LAYER2
Layer1 – 4TB/entry (1 Exabyte represented in one 8M block).
Layer2 – 8MB/entry (4 Gigabytes represented in one 8M block).
Layer1 blockmaps Layer2. Layer2 direct-maps a 64 bit zone offset.
The freemap can validate but not translate zone offsets.
Layer2 – Record zone assignment, append point, bytes free in block
Recent allocation offsets stored in volume header
ZONE:4
VOLUME:8
OFFSET:52
Universal Zone offset, 64 bit, byte granular.
Used everywhere in HAMMER.
16 zones, Zone 0 is reserved.
Direct mapped, no block number translation, but zone can be validated.
Freemap
ZONE:4
LAYER1:18
LAYER2:19
BLKOFF:23