Commit d10b27ef authored by Iustin Pop's avatar Iustin Pop
Browse files

Change the node N+1 check model

Currently, we fail a new instance placement if the new node status is
not N+1 compliant. This means that an allocation on an already N+1
failed node still fails, even though (conceptually) we're not worse than

This patch changes this model to fail the allocation *only* if the node
was N+1 compliant before. This allows balancing to work on non-N+1 happy
clusters, with the caveat that they probably won't be N+1 happy at the

Since we skip N+1 check in some cases, we add a new “failHealth” check
that verifies the node still has strict positive free memory and disk
parent 2cf878a5
......@@ -87,6 +87,10 @@ computeFailN1 :: Int -> Int -> Int -> Bool
computeFailN1 new_rmem new_mem new_dsk =
new_mem <= new_rmem || new_dsk <= 0
-- | Given the new free memory and disk, fail if any of them is below zero.
failHealth :: Int -> Int -> Bool
failHealth new_mem new_dsk = new_mem <= 0 || new_dsk <= 0
-- | Computes the maximum reserved memory for peers from a peer map.
computeMaxRes :: PeerMap.PeerMap -> PeerMap.Elem
computeMaxRes new_peers = PeerMap.maxElem new_peers
......@@ -144,7 +148,7 @@ addPri t inst =
new_mem = f_mem t - Instance.mem inst
new_dsk = f_dsk t - Instance.dsk inst
new_failn1 = computeFailN1 (maxRes t) new_mem new_dsk in
if new_failn1 then
if (failHealth new_mem new_dsk) || (new_failn1 && not (failN1 t)) then
let new_plist = iname:(plist t)
......@@ -159,12 +163,13 @@ addSec :: Node -> Instance.Instance -> Int -> Maybe Node
addSec t inst pdx =
let iname = Instance.idx inst
old_peers = peers t
old_mem = f_mem t
new_dsk = f_dsk t - Instance.dsk inst
new_peem = PeerMap.find pdx old_peers + Instance.mem inst
new_peers = PeerMap.add pdx new_peem old_peers
new_rmem = max (maxRes t) new_peem
new_failn1 = computeFailN1 new_rmem (f_mem t) new_dsk in
if new_failn1 then
new_failn1 = computeFailN1 new_rmem old_mem new_dsk in
if (failHealth old_mem new_dsk) || (new_failn1 && not (failN1 t)) then
let new_slist = iname:(slist t)
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