Commit Graph
4 Commits
Author SHA1 Message Date
Chris Lu 4f50c5b0d4 feat: throughput limits for replicate, EC shard, and worker-driven moves (#10749)
* feat: throughput limits for replicate, EC shard, and worker-driven moves

VolumeCopy was the only rate-limitable transfer; EC shard copies,
replica creation, and worker-driven moves all ran at whatever the
receiving server's maintenance rate allowed, with no per-operation
control.

- proto: VolumeEcShardsCopyRequest and the balance / ec_balance task
  params and configs gain io_byte_per_second; 0 keeps today's behavior
  (the volume server's own maintenance rate governs).
- volume server: VolumeEcShardsCopy throttles with one WriteThrottler
  per request, shared across the shard, .ecx, .ecj, .vif, and .ecsum
  copies so the limit caps the transfer as a whole - the same shape as
  VolumeCopy.
- volume_move: ReplicateVolume accepts the limit; EcMoveOptions carries
  it through MoveEcShards/CopyAndMountEcShards into the copy request,
  with fake-client tests asserting propagation.
- shell: ec.balance gains -ioBytePerSecond; volume.tier.move's
  replication top-up honors the command's existing -ioBytePerSecond
  instead of running unthrottled.
- worker: balance and ec_balance configs gain io_byte_per_second
  (surfaced in the admin config schema), carried through detection and
  plugin job parameters into task params and handed to the shared
  mover; batch balance jobs inherit the limit from their detection
  results.

The limit is per copy stream, so maxParallelization multiplies the
aggregate ceiling.

* worker plugins: expose io_byte_per_second in the plugin config and derive it

The plugin-driven detection path derives its task Config from the
plugin configuration values, and both balance and ec_balance left
IoBytePerSecond at zero there - a configured limit silently reverted
to the server maintenance rate. Both derive functions now read the
field (clamped at zero), and the plugin descriptors expose it with
defaults so the configuration form carries it.
2026-08-13 13:22:58 -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 9dd43ca006 fix balance fallback replica placement (#8824) 2026-03-29 00:05:42 -07:00
Chris Lu 8056b702ba feat(balance): replica placement validation for volume moves (#8622)
* feat(balance): add replica placement validation for volume moves

When the volume balance detection proposes moving a volume, validate
that the move does not violate the volume's replication policy (e.g.,
ReplicaPlacement=010 requires replicas on different racks). If the
preferred destination violates the policy, fall back to score-based
planning; if that also violates, skip the volume entirely.

- Add ReplicaLocation type and VolumeReplicaMap to ClusterInfo
- Build replica map from all volumes before collection filtering
- Port placement validation logic from command_volume_fix_replication.go
- Thread replica map through collectVolumeMetrics call chain
- Add IsGoodMove check in createBalanceTask before destination use

* address PR review: extract validation closure, add defensive checks

- Extract validateMove closure to eliminate duplicated ReplicaLocation
  construction and IsGoodMove calls
- Add defensive check for empty replica map entries (len(replicas) == 0)
- Add bounds check for int-to-byte cast on ExpectedReplicas (0-255)

* address nitpick: rp test helper accepts *testing.T and fails on error

Prevents silent failures from typos in replica placement codes.

* address review: add composite replica placement tests (011, 110)

Test multi-constraint placement policies where both rack and DC
rules must be satisfied simultaneously.

* address review: use struct keys instead of string concatenation

Replace string-concatenated map keys with typed rackKey/nodeKey
structs to eliminate allocations and avoid ambiguity if IDs
contain spaces.

* address review: simplify bounds check, log fallback error, guard source

- Remove unreachable ExpectedReplicas < 0 branch (outer condition
  already guarantees > 0), fold bounds check into single condition
- Log error from planBalanceDestination in replica validation fallback
- Return false from IsGoodMove when sourceNodeID not found in
  existing replicas (inconsistent cluster state)

* address review: use slices.Contains instead of hand-rolled helpers

Replace isAmongDC and isAmongRack with slices.Contains from the
standard library, reducing boilerplate.
2026-03-13 17:39:25 -07:00