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storage/allocator_test.go, line 529 at r1 (raw file):

      // test the case where 3 nodes are above the mean but below the rebalancer's
      // target range count but one node is well below the mean. We still want to
      // rebalance to severely underused stores.

Can you add that scenario here, verify it fails and then comment it out?

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Review status: 0 of 1 files reviewed at latest revision, 3 unresolved discussions, all commit checks successful.

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storage/allocator_test.go, line 469 at r1 (raw file):

storage/allocator_test.go, line 501 at r1 (raw file):

storage/allocator_test.go, line 529 at r1 (raw file):

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Reviewed 1 of 1 files at r2.
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storage/allocator_test.go, line 475 at r2 (raw file):

  // should be rebalanced from.
  oneStoreAboveRebalanceTarget := func(mean int32, numStores int) []testStore {
      if minStores := 4; numStores < minStores {

why 4? extract a constant to share with oneUnderusedStore and anchor a comment on it.

storage/allocator_test.go, line 482 at r2 (raw file):

          stores[i].rangeCount = mean
      }
      thresholdDelta := int32(float64(mean)*rebalanceThreshold + 1)

perhaps surplus for consistency with deficit below? the math here seems sketchy, too, in that unlike below, the first and last replicas will be exact mirrors. i thought the intention was to have one outlier store.

storage/allocator_test.go, line 489 at r2 (raw file):

  }

  // Returns a slice of stores with the specified mean (fill in TBD)

Looks like you forgot to flesh out this comment.

storage/allocator_test.go, line 494 at r2 (raw file):

          t.Fatalf("# of stores %d < min %d", numStores, minStores)
      }
      stores := make([]testStore, 10)

s/10/numStores/?

storage/allocator_test.go, line 498 at r2 (raw file):

          stores[i].rangeCount = mean
      }
      // Subtract a large number of ranges from the first store and add that delta

better if you clarify "large". it seems to be the minimum number that will trigger the rebalancer's heuristic?

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Review status: 0 of 1 files reviewed at latest revision, 8 unresolved discussions.

storage/allocator_test.go, line 475 at r2 (raw file):

storage/allocator_test.go, line 482 at r2 (raw file):

storage/allocator_test.go, line 489 at r2 (raw file):

storage/allocator_test.go, line 494 at r2 (raw file):

storage/allocator_test.go, line 498 at r2 (raw file):

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Reviewed 1 of 1 files at r3.
Review status: all files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

Comments from Reviewable