21126: Add doc comment to AllowTrashWhenReadOnly config.

[arvados.git] / lib / config / config.default.yml

diff --git a/lib/config/config.default.yml b/lib/config/config.default.yml
index b78116255a14687208dace80d212dae452bbac80..9155a8edaa36352e6c687b58b991e8564d6051e5 100644 (file)
--- a/lib/config/config.default.yml
+++ b/lib/config/config.default.yml
@@ -225,7 +225,17 @@ Clusters:
 
       # Maximum number of concurrent requests to process concurrently
       # in a single service process, or 0 for no limit.
-      MaxConcurrentRequests: 4
+      #
+      # Note this applies to all Arvados services (controller, webdav,
+      # websockets, etc.). Concurrency in the controller service is
+      # also effectively limited by MaxConcurrentRailsRequests (see
+      # below) because most controller requests proxy through to the
+      # RailsAPI service.
+      MaxConcurrentRequests: 64
+
+      # Maximum number of concurrent requests to process concurrently
+      # in a single RailsAPI service process, or 0 for no limit.
+      MaxConcurrentRailsRequests: 8
 
       # Maximum number of incoming requests to hold in a priority
       # queue waiting for one of the MaxConcurrentRequests slots to be
@@ -1212,11 +1222,14 @@ Clusters:
         # before being silenced until the end of the period.
         LogThrottleLines: 1024
 
-        # Maximum bytes that may be logged by a single job.  Log bytes that are
-        # silenced by throttling are not counted against this total.
-        # If you set this to zero, each container will only create a single
-        # log on the API server, noting for users that logging is throttled.
-        LimitLogBytesPerJob: 67108864
+        # Maximum bytes that may be logged as legacy log events
+        # (records posted to the "logs" table). Starting with Arvados
+        # 2.7, container live logging has migrated to a new system
+        # (polling the container request live log endpoint) and this
+        # value should be 0.  As of this writing, the container will
+        # still create a single log on the API server, noting for that
+        # log events are throttled.
+        LimitLogBytesPerJob: 0
 
         LogPartialLineThrottlePeriod: 5s
 
@@ -1421,16 +1434,17 @@ Clusters:
         # as containers start up successfully and decreases in
         # response to high API load and cloud quota errors.
         #
-        # Setting this too high creates a risk that the dispatcher
-        # will cause deadlock by starting so many supervisor
-        # containers (based on SupervisorFraction and MaxInstances)
-        # that the cloud quota prevents them from running any child
-        # containers.
+        # Setting this to 0 means the dynamic instance limit will
+        # start at MaxInstances.
         #
-        # Setting this too low causes the dispatcher to be
-        # unnecessarily slow to start up new instances after a
-        # restart.
-        InitialQuotaEstimate: 16
+        # Situations where you may want to set this (to a value less
+        # than MaxInstances) would be when there is significant
+        # variability or uncertainty in the actual cloud resources
+        # available.  Upon reaching InitialQuotaEstimate the
+        # dispatcher will switch to a more conservative behavior with
+        # slower instance start to avoid over-shooting cloud resource
+        # limits.
+        InitialQuotaEstimate: 0
 
         # Maximum fraction of available instance capacity allowed to
         # run "supervisor" containers at any given time. A supervisor
@@ -1444,9 +1458,9 @@ Clusters:
         # containers who just create more work.
         #
         # For example, with the default MaxInstances of 64, it will
-        # schedule at most floor(64*0.30) = 19 concurrent workflows,
-        # ensuring 45 slots are available for work.
-        SupervisorFraction: 0.30
+        # schedule at most floor(64*0.50) = 32 concurrent workflow
+        # runners, ensuring 32 slots are available for work.
+        SupervisorFraction: 0.50
 
         # Interval between cloud provider syncs/updates ("list all
         # instances").
@@ -1531,10 +1545,23 @@ Clusters:
           SecretAccessKey: ""
 
           # (ec2) Instance configuration.
+
+          # (ec2) Region, like "us-east-1".
+          Region: ""
+
+          # (ec2) Security group IDs. Omit or use {} to use the
+          # default security group.
           SecurityGroupIDs:
             "SAMPLE": {}
+
+          # (ec2) One or more subnet IDs. Omit or leave empty to let
+          # AWS choose a default subnet from your default VPC. If
+          # multiple subnets are configured here (enclosed in brackets
+          # like [subnet-abc123, subnet-def456]) the cloud dispatcher
+          # will detect subnet-related errors and retry using a
+          # different subnet. Most sites specify one subnet.
           SubnetID: ""
-          Region: ""
+
           EBSVolumeType: gp2
           AdminUsername: debian
           # (ec2) name of the IAMInstanceProfile for instances started by
@@ -1667,6 +1694,11 @@ Clusters:
             ReadOnly: false
           "http://host1.example:25107": {}
         ReadOnly: false
+        # AllowTrashWhenReadOnly enables unused and overreplicated
+        # blocks to be trashed/deleted even when ReadOnly is
+        # true. Normally, this is false and ReadOnly prevents all
+        # trash/delete operations as well as writes.
+        AllowTrashWhenReadOnly: false
         Replication: 1
         StorageClasses:
           # If you have configured storage classes (see StorageClasses