etcd-quorum-read flag: explicitly default to off for v2 #4792
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Kubernetes 1.9 changed the default for etcd-quorum-read flag value to true, in the hope of fixing some of the edge-case controller issues. However, while this is cheap on etcd3, that fix was not backported to etcd2, and performance there of quorum reads is poor. For non-HA clusters with etcd2, it still goes through raft, but does not need to - we set etcd-quorum-read to false, as this is just a missed optimization in etcd2. For HA clusters with etcd2, it's trickier, but at least for now we're going to avoid the (crippling) performance regression. kops 1.10 should have etcd-manager (allowing upgrades to etcd3), and the ability to configure IOPS on the etcd volume, so we can revisit this in 1.10 / 1.11.
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chrislovecnm
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Mar 25, 2018
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Merging this since @justinsb is going to send in a test for e2e. |
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/lgtm |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: chrislovecnm, justinsb The full list of commands accepted by this bot can be found here. The pull request process is described here
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blakebarnett
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Kubernetes 1.9 changed the default for etcd-quorum-read flag value to
true, in the hope of fixing some of the edge-case controller issues.
However, while this is cheap on etcd3, that fix was not backported to
etcd2, and performance there of quorum reads is poor.
For non-HA clusters with etcd2, it still goes through raft, but does not
need to - we set etcd-quorum-read to false, as this is just a missed
optimization in etcd2.
For HA clusters with etcd2, it's trickier, but at least for now we're
going to avoid the (crippling) performance regression. kops 1.10 should
have etcd-manager (allowing upgrades to etcd3), and the ability to
configure IOPS on the etcd volume, so we can revisit this in 1.10 /
1.11.