Eevans has uploaded a new change for review.

  https://gerrit.wikimedia.org/r/292305

Change subject: limit mmap'd disk access to indexes only on Cassandra 2.2
......................................................................

limit mmap'd disk access to indexes only on Cassandra 2.2

I'm not completely certain what the problem is here, but in our environment
where everything is compressed, this effectively undoes the mmap'd reads
performed by decompression in 2.2, reverting to the behavior of 2.1.  More
investigation is needed, but `disk_access_mode: auto` (the default) results
in unacceptably high disk read throughput.

Bug: T126629
Change-Id: Ic394515e56ab88c0f63caaedd2d18203301bf9bf
---
M modules/cassandra/templates/cassandra.yaml-2.2.erb
1 file changed, 3 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.wikimedia.org:29418/operations/puppet 
refs/changes/05/292305/1

diff --git a/modules/cassandra/templates/cassandra.yaml-2.2.erb 
b/modules/cassandra/templates/cassandra.yaml-2.2.erb
index f6474e5..4f4d153 100644
--- a/modules/cassandra/templates/cassandra.yaml-2.2.erb
+++ b/modules/cassandra/templates/cassandra.yaml-2.2.erb
@@ -892,3 +892,6 @@
 # below their system default. The sysinternals 'clockres' tool can confirm 
your system's default
 # setting.
 windows_timer_interval: 1
+
+# Disable mmap'd data reads until further notice (causing loads of page faults)
+disk_access_mode: mmap_index_only

-- 
To view, visit https://gerrit.wikimedia.org/r/292305
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Ic394515e56ab88c0f63caaedd2d18203301bf9bf
Gerrit-PatchSet: 1
Gerrit-Project: operations/puppet
Gerrit-Branch: production
Gerrit-Owner: Eevans <[email protected]>

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