The planner refused to create an EC task unless it found totalShards
distinct (server, disk_id) targets, so a cluster with fewer disks than
shards (e.g. 8 single-disk servers for a 10+4 scheme) could never encode.
A disk safely holds several distinct shards of one volume: each is its own
.ecNN file and ReceiveFile keys by that extension. Drop the strict check and
let createECTargets round-robin shards across the available disks, matching
ec.encode's "4,4,3,3" fallback. The minTotalDisks floor (ceil(total/parity))
already keeps any disk under parityShards shards, so the volume still
survives losing any one disk.
Reserve capacity for the actual per-disk shard count rather than assuming
one shard each, so packing doesn't over-commit disk slots.
Chris LuandGitHub
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