mirror of
https://github.com/apache/cloudstack.git
synced 2025-11-04 00:02:37 +01:00
46 lines
2.7 KiB
XML
46 lines
2.7 KiB
XML
<?xml version='1.0' encoding='utf-8' ?>
|
|
<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "file:///C:/Program%20Files%20(x86)/Publican/DocBook_DTD/docbookx.dtd" [
|
|
<!ENTITY % BOOK_ENTITIES SYSTEM "cloudstack.ent">
|
|
%BOOK_ENTITIES;
|
|
]>
|
|
|
|
<!-- Licensed to the Apache Software Foundation (ASF) under one
|
|
or more contributor license agreements. See the NOTICE file
|
|
distributed with this work for additional information
|
|
regarding copyright ownership. The ASF licenses this file
|
|
to you under the Apache License, Version 2.0 (the
|
|
"License"); you may not use this file except in compliance
|
|
with the License. You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing,
|
|
software distributed under the License is distributed on an
|
|
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
|
|
KIND, either express or implied. See the License for the
|
|
specific language governing permissions and limitations
|
|
under the License.
|
|
-->
|
|
|
|
<section id="snapshot-throttling">
|
|
<title>Snapshot Job Throttling</title>
|
|
<para>When a snapshot of a virtual machine is requested, the snapshot job runs on the same
|
|
host where the VM is running or, in the case of a stopped VM, the host where it ran last. If
|
|
many snapshots are requested for VMs on a single host, this can lead to problems with too
|
|
many snapshot jobs overwhelming the resources of the host.</para>
|
|
<para>To address this situation, the cloud's root administrator can throttle how many snapshot
|
|
jobs are executed simultaneously on the hosts in the cloud by using the global configuration
|
|
setting concurrent.snapshots.threshold.perhost. By using this setting, the administrator can
|
|
better ensure that snapshot jobs do not time out and hypervisor hosts do not experience
|
|
performance issues due to hosts being overloaded with too many snapshot requests.</para>
|
|
<para>Set concurrent.snapshots.threshold.perhost to a value that represents a best guess about
|
|
how many snapshot jobs the hypervisor hosts can execute at one time, given the current
|
|
resources of the hosts and the number of VMs running on the hosts. If a given host has more
|
|
snapshot requests, the additional requests are placed in a waiting queue. No new snapshot
|
|
jobs will start until the number of currently executing snapshot jobs falls below the
|
|
configured limit.</para>
|
|
<para>The admin can also set job.expire.minutes to place a maximum on how long a snapshot
|
|
request will wait in the queue. If this limit is reached, the snapshot request fails and
|
|
returns an error message. </para>
|
|
</section>
|