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2 Commits
Author SHA1 Message Date
Chris Lu 7e608c877a refactor(ec_balance): make the balance planner per-volume ratio-capable (#9960)
* refactor(ec_balance): make the balance planner per-volume ratio-capable

Thread a per-volume EC ratio through the balance planner: Plan resolves each
volume's data/parity from a new Options.VolumeRatio (falling back to the
collection Ratio, then the build default, when it reports 0), and keys the
global phase's ratio maps by volume instead of collection. The shell and
worker balance paths build the per-volume lookup from each shard's heartbeat
via the new ecbalancer.VolumeShardRatio.

In OSS this is behavior-preserving: VolumeShardRatio returns 0 because the
per-volume data_shards/parity_shards heartbeat fields are an enterprise
feature, so every volume falls back to the collection ratio -- the existing
standard-scheme behavior. The refactor keeps the shared planner in sync with
the enterprise fork, which overrides VolumeShardRatio to classify and spread
a mixed-ratio collection by each volume's own data/parity split.

* perf(ec_balance): hoist the collection ratio out of the per-volume loop

The collection ratio is constant for every volume in a collection, so
resolve it once per collection instead of per volume; a custom Ratio func
may do map lookups or locking. Addresses a review comment.
2026-06-14 11:33:31 -07:00
Chris Lu d4e39b499b EC placement: shared replica-placement resolver, snapshot + Place core, capacity fixes, tiering (#9621)
* Add shared super_block.ResolveReplicaPlacement; use it in ec_balance

* Add ecbalancer.FromActiveTopology snapshot constructor for EC encode/repair

* Add ecbalancer.Place greenfield/repair placement core (strict + durability-first)

* topology: add GetEffectiveAvailableEcShardSlots; FromActiveTopology uses shard-granular free slots

GetDisksWithEffectiveCapacity flattens reserved shard slots into volume slots via
integer truncation, so an in-flight EC task reserving a non-multiple-of-
DataShardsCount number of shards was lost from the snapshot and freeSlots was
over-reported. GetEffectiveAvailableEcShardSlots subtracts the full reservation
impact at shard granularity.

* ecbalancer.Place: reject nodes without a free disk of the requested type

FromActiveTopology keeps all disk types in the snapshot, so an SSD-only request
could be routed to a node with only HDD capacity (pickBestDiskOnNode then returns
disk 0 on the wrong tier). Filter rack/node selection to those with a free disk
of the requested type.

* ecbalancer.Place: enforce ReplicaPlacement DiffDataCenterCount (per-DC shard cap)

* ecbalancer: enforce DiffDataCenterCount in balance (cross-DC phase + cross-rack DC cap)

Adds a cross-DC corrective phase that drains data centers holding more than
DiffDataCenterCount shards of a volume, and a per-DC cap on cross-rack move
targets. Both are no-ops when DiffDataCenterCount is unset, so balance output is
unchanged for non-DC placements.

* topology: ratio-aware EC shard slots and provisional empty-disk slot

GetEffectiveAvailableEcShardSlots now takes the target collection's data-shard
count, so a 4+2 volume's larger shards are not over-counted at 10 per volume slot;
and it keeps the one provisional slot for freshly started empty servers that
report max=0, matching getEffectiveAvailableCapacityUnsafe. FromActiveTopology
threads the ratio through.

* ecbalancer.Place: explicit disk-type filter signal (fix HDD vs any ambiguity)

HardDriveType normalizes to "", which collided with "" meaning any disk. Add
Constraints.FilterDiskType and normalize both sides so a hdd request matches disks
reported as "" and never leaks to SSD, while filter=false still means any.

* ecbalancer: add clearShardAccounting for repair snapshot reconciliation

Clears one disk's copy of a shard from per-domain accounting and recomputes the
node-level union (preserving a kept copy on another disk of the same node), without
crediting capacity. Repair uses it to drop to-be-deleted copies before placing
missing shards.

* ecbalancer: don't cap cross-DC target racks when DiffRackCount is unset

len(racks)+1 wrongly limited each target rack (3 in a 2-rack cluster), so draining
a DC could stop short of the DiffDataCenterCount cap. Use MaxShardCount+1 as the
effectively-unlimited default.

* topology/ecbalancer: ratio-correct EC capacity accounting

Reservation shard slots (default ShardsPerVolumeSlot units) are now converted to
the target ratio before subtracting, and existing EC shards are charged by size
(targetDataShards/shardDataShards) so a 2+1 shard isn't counted as one 10+4 slot.
Per-shard ratio lookup is behind shardDataShards (OSS uses the standard ratio).

* ecbalancer.Place: candidate tiering and eligible-rack caps

Adds a per-disk eligibility/preference abstraction so Place supports:
- preferred-tag whole-plan retry (try disks carrying the earliest tags first,
  widen to all only if a tier cannot place every shard; reports
  SpilledOutsidePreferredTags),
- soft disk-type spill via DiskTypePolicy (Any/Prefer/Require): Prefer fills the
  preferred type then spills, reporting SpilledToOtherDiskType; Require filters,
- even per-rack caps that divide by racks holding an eligible disk, so a tiered
  cluster (e.g. SSDs in 2 of 4 racks) isn't capped impossibly low.
Disk tags carried via Node.AddDiskTags + FromActiveTopology.

* ecbalancer: export ClearShardAccounting for repair snapshot reconciliation

* ecbalancer: address review feedback (ratio rounding, bitmap walk, same-DC moves)

- topology/ecbalancer: round shard-reservation and existing-shard footprint up
  when converting to target-ratio shard slots, so a sub-slot reservation is not
  truncated to zero and free capacity is not overstated for low-data-shard
  layouts (targetDataShards < ds).
- erasure_coding: add ShardBits.All iterator and use it across the balancer,
  cross-DC phase, and placement scoring instead of scanning 0..MaxShardCount and
  probing Has on every id.
- ecbalancer: allow same-DC cross-rack moves when a DC already sits at its
  DiffDataCenterCount cap; a same-DC move leaves the DC total unchanged. Add a
  regression test that fails without the guard.
- ecbalancer cross-DC phase: pick targets via the eligible-aware
  pickNodeInRackEligible/pickBestDiskEligible helpers so the disk-type filter is
  honored and a 0 disk id is not mistaken for a valid selection.

* ecbalancer: test ecShardSlotsOnDisk fractional round-up

Cover the mixed-ratio path (targetDataShards < existing data shards) so a
shard's fractional footprint is never floored to zero and free capacity is not
overstated. Exercises the round-up via the targetDataShards parameter; OSS uses
the standard ratio at runtime while the enterprise build hits it with real
per-volume ratios.

* ecbalancer: assert node B rack in TestFromActiveTopology

* ecbalancer: split Destination into separate DataCenter and bare Rack

Replace the composite "dc:rack" Rack field on Destination with separate
DataCenter and bare Rack values, matching topology.DiskInfo and the worker-task
convention. Callers (and tests) read the data center directly instead of parsing
the composite with strings.SplitN.

* shell ec.balance: use utilization-based global balancing (parity with worker)

The shell's global rebalance phase balanced by raw shard count; switch it to
fractional fullness (shards/capacity), as the worker already does. On uniform
capacity the two agree; on heterogeneous capacity it fills nodes proportionally
instead of driving small-capacity nodes toward full.

Updates the heterogeneous-capacity regression test to assert even fullness
(~equal shards/capacity per node) rather than even shard count.

* ecbalancer: bounded-proportional per-DC shard spread

DiffDataCenterCount was enforced only as a ceiling (drain-to-cap), which could
leave a within-cap-but-lopsided DC distribution under a loose cap (e.g. 10/4 of 14
with cap=10). Now the cross-DC phase, the cross-rack DC guard, and Place all target
boundedMaxPerDC = min(DiffDataCenterCount, max(ceil(total/numDCs), parityShards)):
shards spread proportionally across DCs, but no tighter than the durability floor
(once each DC holds <= parityShards a DC loss is recoverable, so further spreading
only adds cross-DC/WAN traffic). No-op when DiffDataCenterCount is 0; identical to
before when the cap is the binding constraint.

* ecbalancer: drop DiffDataCenterCount enforcement for EC placement

The 1-byte volume ReplicaPlacement packs xyz into x*100+y*10+z<=255, so the DC
digit can only be 0-2 -- far too small to be a meaningful per-DC EC shard cap (a
cap of 1-2 would demand 7-14 DCs for a 10+4 volume). It's volume replica-placement,
not an EC spec. Removes the cross-DC balance phase, the DC guard in the cross-rack
phase, and the per-DC cap in Place (and the just-added bounded-proportional logic);
EC relies on the RP-independent rack/node even spread instead. Rack/node caps
(DiffRackCount/SameRackCount) are unchanged. Per-domain EC caps are left for a real
EC placement spec.

* ecbalancer: enforce per-disk durability cap; symmetric reserve/release

Place now refuses to put more than parityShards shards of a volume on a single
disk (pickBestDiskEligible skips a disk once it holds parityShards of the volume,
a hard cap not relaxed even in durability-first). Previously Place assigned by
free capacity, so a skewed near-full cluster could pile >parityShards onto one
disk -> losing it loses the volume; only distinct-disk count was checked. This
covers encode and repair (both route through Place); the caller skips/leaves the
volume rather than minting an unrecoverable layout.

Also makes reserveShard decrement freeSlots unconditionally, symmetric with
releaseShard's unconditional increment (the old guarded decrement could credit a
phantom slot on release if a shard were ever reserved onto a full disk).

* ecbalancer: add Topology.ReleaseVolumeShards (clear + credit) for greenfield encode

Releases all of a volume's shards from the snapshot and credits the freed disk
capacity, so a greenfield encode can plan as if stale EC shards from a prior failed
attempt are gone. Safe to credit because the encode task deletes stale shards
(cleanupStaleEcShards) before distributing the new ones. Distinct from
ClearShardAccounting (repair), which does not credit.

* ecbalancer: ReleaseVolumeShards credits node freeSlots, not just disks

releaseShard only increments per-disk freeSlots, but rack capacity is summed from
node freeSlots (buildRacks) and node freeSlots gates node eligibility. Crediting
only disks left a node/rack looking full after releasing stale shards, so a
greenfield encode still couldn't use the freed capacity. Now credits the node by
the total disk-slots freed.

* ecbalancer: correct PlacementMode docs (encode uses durability-first)

PlaceStrict was labeled '(encode)' but encode uses PlaceDurabilityFirst. Clarify
that durability-first is used by both encode and repair, reports relaxations in
PlaceResult.Relaxed, and never relaxes the per-disk durability cap.

* ecbalancer: treat SameRackCount as a direct per-node shard cap

The 3rd ReplicaPlacement digit now caps shards per node at exactly the digit
value, matching how DiffRackCount (2nd digit) caps per rack, instead of allowing
digit+1 per node. This makes the per-rack and per-node caps consistent and
matches the documented "digits cap EC shards per rack and per node" semantics;
e.g. 011 now means at most one shard per rack and one per node.
2026-05-22 20:22:09 -07:00