3 Commits

Include renames

Author	SHA1	Message	Date
Chris Lu	f9d3105e80	ec placement: spread EC shards evenly across machines, not onto the lowest-id one (#9855) ... * ec placement: steer shards to less-loaded machines, not the lowest id EC encode places every volume against one shared topology snapshot (it reserves the shards it assigns so later volumes see reduced capacity), but node selection ranked only by this volume's shard count and broke ties by sorted id. So the lowest-id machine won the first shard of every volume and accumulated far more total shards than the rest -- on a 6-machine cluster the first machines drifted to ~1.5x. Rank eligible nodes by the machine's shards of this volume, then the machine's free capacity, then the node's shards of this volume, then the node's free capacity. Free capacity reflects the load already placed, so ties steer toward the least-loaded machine instead of the lowest id, keeping total EC shards even across machines. * test: ec.balance converges to even per-machine load from a skew Starts machine 10.0.0.1 at 4 shards/volume and the rest at 2, then runs repeated worker-style capped passes; asserts convergence to an even per-machine total (reaches exactly even in ~13 rounds). * reduce comments on the placement fix Trim narration to the non-obvious why. * test: assert convergence and count zero-shard machines Seed the per-machine map with every host so a fully drained machine still registers, and fail explicitly if balance doesn't converge before the round cap.	2026-06-07 20:45:17 -07:00
Chris Lu	f0d2a0d417	Treat co-located volume servers as one fault domain when balancing and allocating (#9854) ... * admin/topology: carry the volume server address on DiskInfo The planning DiskInfo exposed only the node id, which can be an opaque label rather than ip:port. Record the address too so callers can resolve the physical machine a disk sits on. * ec.balance: spread a volume's shards across machines, not just nodes Volume servers sharing a host are one fault domain, but the within-rack spread treated them as independent nodes, so one box could end up holding more shards of a volume than EC can afford to lose. Add a machine (host) tier between rack and node: the within-rack pass spreads each volume across machines, and the global load phase no longer re-concentrates a volume onto a machine it already sits on. Host defaults to the node id, so clusters with one server per host are unchanged. * ec placement: prefer machines holding fewer of a volume's shards EC allocation and repair picked the least-loaded node in a rack with no regard for which physical machine it sits on, so a volume's shards could pile onto several servers of one box. Rank candidate nodes by their machine's shard count first, then the node's own. The machine is derived from the volume server address carried on DiskInfo, falling back to the node id, matching how the balancer resolves it. * volume.balance: don't move a replica onto a machine already holding one isGoodMove only rejected a move onto the same data node, so two replicas could land on two volume servers of one box and a single machine failure would lose both. Reject a target whose host already holds another replica of the volume. Best-effort: balancing simply skips and tries the next target. * volume allocation: spread same-rack replicas across machines PickNodesByWeight filled the same-rack replica picks by weight alone, so replicas could co-locate on one box. Prefer candidates on not-yet-used hosts, falling back when too few distinct machines exist. Data-center and rack tiers have no host, so their ordering is unchanged. * ec.balance: harden machine spread against re-concentration and capped machines Two cases where the machine-aware spread could still leave a volume badly placed: - The global load phase could move a shard of a volume onto a machine that already held it, raising that machine's count and undoing the within-rack spread (a 4/4/3/3 layout could become 3/5/3/3, past parity for 10+4). Limit the load-only fallback to same-machine moves, which leave a machine's count unchanged; cross-machine concentration is no longer allowed for load alone. - The within-rack spread chose a destination machine by free slots alone, so if that machine's only nodes were already at the SameRackCount cap it skipped the move instead of trying another machine. Require a machine to have a node that can actually take the shard before selecting it. * reduce comments across the machine-affinity change Trim narration down to the non-obvious why; one terse line where a block was overkill. * ec.balance: gate machine spread on fault-tolerance feasibility Spreading a volume evenly across machines only helps when there are enough that each can stay within EC's parity tolerance (numMachines >= ceil(total/parity)). With fewer -- or wildly unequal -- machines it can't make a machine loss survivable anyway, and forcing it fights capacity: e.g. a cluster of 12 volume servers on one host and 2 on another would have half of every volume crammed onto the 2-server box. So spread across machines only when it's achievable; otherwise fall back to per-node spread and let capacity/global balancing decide. The global load phase applies the same test: it protects a volume's machine spread (no cross-machine move that raises a machine's count past the source's) only where that spread is achievable, so heterogeneous clusters still level by fullness. * ec.balance worker: group servers by host when planning The worker built its planner topology without recording each server's host, so automated ec.balance treated ports on one machine as independent nodes and could concentrate a volume's shards on one physical box. Set the host from the volume server address, matching the shell path. * volume.balance worker: don't move a replica onto a machine holding one The worker compared only node ids, and the replica map dropped the server address, so it could move replicas onto different ports of one machine. Carry the host on ReplicaLocation (from the server address) and reject a target whose host already holds another replica of the volume. Best-effort, matching the shell. * ec.balance: judge machine-spread feasibility by the rack's shards The within-rack and global feasibility checks compared the whole volume's shard count against a rack's machine count, so a rack holding only part of a volume after cross-rack spreading -- e.g. 7 of a 10+4 volume across 2 machines -- was wrongly judged infeasible and fell back to node spread, which could pile 6 shards onto one host, past parity. Gate on the rack's own shard count of the volume instead. * ec.balance: spread a volume's shards across machines by combined count EC recovers from any loss within parity regardless of shard type, so what bounds a machine's exposure is its total shards of the volume, not data and parity separately. Spreading the two independently let each type's remainder land on the same machine -- ceil(d/M)+ceil(p/M) can exceed ceil(total/M), e.g. a 5/3 split where 4/4 was achievable, past parity. Balance the combined count in one pass; disk-level data/parity anti-affinity stays in pickBestDiskOnNode. * ec.balance: don't let the imbalance threshold skip an over-parity machine The within-rack spread gated on relative skew ((max-min)/avg > threshold), so a worker threshold of 0.5 skipped an exactly-50%-skewed layout like 5/4/3 for a 10+4 volume, leaving 5 shards -- past parity -- on one machine. The even cap (ceil(shards/groups)) is the real bound and the move loop already sheds only what exceeds it, so drop the threshold gate from the within-rack phase (machine and node): a balanced rack stays a no-op while any over-cap machine is always fixed. * ec.balance: keep the imbalance threshold for the node fallback Dropping the threshold from the whole within-rack phase made the node fallback too eager: it runs only when machine fault tolerance is unachievable, so it is cosmetic load distribution that should defer to the global utilization phase. Without the gate it would, for a one-server-per-host 6/4 split at threshold 0.5, schedule a count move that worsens utilization balance. Restore the threshold there; machine spreading keeps bypassing it, since that bound is durability, not cosmetic skew.	2026-06-07 14:14:45 -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