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Subject [26/43] git commit: refs/heads/regions - Docs. CLOUDSTACK-304. New section: snapshot-throttling.xml. In working-with-snapshots.xml: include the new section.
Date Thu, 31 Jan 2013 17:07:19 GMT
Docs. CLOUDSTACK-304. New section: snapshot-throttling.xml. In working-with-snapshots.xml:
include the new section.


Branch: refs/heads/regions
Commit: bf4e21716546beda600af478b0fe11e9dd2263ec
Parents: 7dbbdd5
Author: Jessica Tomechak <>
Authored: Wed Jan 30 16:17:44 2013 -0800
Committer: Jessica Tomechak <>
Committed: Wed Jan 30 16:37:51 2013 -0800

 docs/en-US/snapshot-throttling.xml    |   26 ++++++++++++++++++++++++++
 docs/en-US/working-with-snapshots.xml |    1 +
 2 files changed, 27 insertions(+), 0 deletions(-)
diff --git a/docs/en-US/snapshot-throttling.xml b/docs/en-US/snapshot-throttling.xml
new file mode 100644
index 0000000..f1af08a
--- /dev/null
+++ b/docs/en-US/snapshot-throttling.xml
@@ -0,0 +1,26 @@
+<?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">
+<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
+        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
+        jobs will start until the number of currently executing snapshot jobs falls below
+        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
+        returns an error message. </para>
\ No newline at end of file
diff --git a/docs/en-US/working-with-snapshots.xml b/docs/en-US/working-with-snapshots.xml
index d6b1458..e7e4517 100644
--- a/docs/en-US/working-with-snapshots.xml
+++ b/docs/en-US/working-with-snapshots.xml
@@ -29,4 +29,5 @@
     <para>Snapshots may be taken for volumes, including both root and data disks. The
administrator places a limit on the number of stored snapshots per user. Users can create
new volumes from the snapshot for recovery of particular files and they can create templates
from snapshots to boot from a restored disk.</para>
     <para>Users can create snapshots manually or by setting up automatic recurring
snapshot policies. Users can also create disk volumes from snapshots, which may be attached
to a VM like any other disk volume. Snapshots of both root disks and data disks are supported.
However, &PRODUCT; does not currently support booting a VM from a recovered root disk.
A disk recovered from snapshot of a root disk is treated as a regular data disk; the data
on recovered disk can be accessed by attaching the disk to a VM.</para>
     <para>A completed snapshot is copied from primary storage to secondary storage,
where it is stored until deleted or purged by newer snapshot.</para>
+    <xi:include href="snapshot-throttling.xml" xmlns:xi=""

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