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Posted to dev@cloudstack.apache.org by Alena Prokharchyk <Al...@citrix.com> on 2012/10/09 20:51:26 UTC
FS on cloudStack createSnapshot synchronization improvement
Hi All,
I'm planning to introduce some changes to create snapshot behavior for the
future cloudStack release (the changes will go to asf/master branch). The
fix is fixing the problem described below:
"With the current code for snapshots, cloudStack always creates snapshot
on the host where vm is Running (for vms in Running state) or on the host
where vm used to run the last time (for vms in Stopped state). As the
createSnapshot commands are not synchronized on the agent side, the case
when multiple commands are send to the backend at the same time can lead
to the performance issues on the hypervisor side. At the end there is a
high possibility that createSnapshot command might time out on the Xen
side.
The solution is to synchronize number of concurrent snapshots per host
basis. The threshold should be configurable as the customer usually knows
how many snapshots at a time the backend can handle.
While the concurrent snapshots are being processed by the backend, all
subsequent snapshot commands scheduled for execution on the same host,
should wait in the queue"
Here is the feature FS available for the review:
https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improvement
s+FS
If you have any comments/suggestions/questions on the implementation,
please let me know.
-Alena.
RE: FS on cloudStack createSnapshot synchronization improvement
Posted by Suresh Sadhu <Su...@citrix.com>.
HI,
Please find my review comments on Snapshot Improvement Functional Spec:
1. is this spec is applicable to all hypervisors or specific to Xen.
2. What are the max concurrent snapshots can be run on a host.is there any limit for the threshold? Max/Min/default values per hypervisor.
3. Does the snapshot job queue consider the job retry in case of failures. If yes can you please share how it works.
4. Does this concurrent threshold applies to Backup Snapshot command also.
5. Does this change impact the performance? If yes in what forms?
6. what will be the expected behaviour for the Schedule snapshots jobs on queue for below cases
a) VM state changed from running to stopped & running to destroyed
b) corresponding host went to maintenance mode in a cluster having more than 2 hosts.
7. The time for job.expire.min will be consider as when we initiate the createSnapshot command or when waiting job dequeued from the sync_queue_item table.
https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improvements+FS
Regards
Sadhu
-----Original Message-----
From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
Sent: 10 October 2012 00:21
To: cloudstack-dev@incubator.apache.org
Subject: FS on cloudStack createSnapshot synchronization improvement
Hi All,
I'm planning to introduce some changes to create snapshot behavior for the future cloudStack release (the changes will go to asf/master branch). The fix is fixing the problem described below:
"With the current code for snapshots, cloudStack always creates snapshot on the host where vm is Running (for vms in Running state) or on the host where vm used to run the last time (for vms in Stopped state). As the createSnapshot commands are not synchronized on the agent side, the case when multiple commands are send to the backend at the same time can lead to the performance issues on the hypervisor side. At the end there is a high possibility that createSnapshot command might time out on the Xen side.
The solution is to synchronize number of concurrent snapshots per host basis. The threshold should be configurable as the customer usually knows how many snapshots at a time the backend can handle.
While the concurrent snapshots are being processed by the backend, all subsequent snapshot commands scheduled for execution on the same host, should wait in the queue"
Here is the feature FS available for the review:
https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improvement
s+FS
If you have any comments/suggestions/questions on the implementation, please let me know.
-Alena.
RE: FS on cloudStack createSnapshot synchronization improvement
Posted by Anthony Xu <Xu...@citrix.com>.
Do we have plan to separate create snapshot and backup snapshot?
If that's true, only backup snapshot commands need to be synchronized since creating snapshot is fast.
-----Original Message-----
From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
Sent: Tuesday, October 09, 2012 11:51 AM
To: cloudstack-dev@incubator.apache.org
Subject: FS on cloudStack createSnapshot synchronization improvement
Hi All,
I'm planning to introduce some changes to create snapshot behavior for the future cloudStack release (the changes will go to asf/master branch). The fix is fixing the problem described below:
"With the current code for snapshots, cloudStack always creates snapshot on the host where vm is Running (for vms in Running state) or on the host where vm used to run the last time (for vms in Stopped state). As the createSnapshot commands are not synchronized on the agent side, the case when multiple commands are send to the backend at the same time can lead to the performance issues on the hypervisor side. At the end there is a high possibility that createSnapshot command might time out on the Xen side.
The solution is to synchronize number of concurrent snapshots per host basis. The threshold should be configurable as the customer usually knows how many snapshots at a time the backend can handle.
While the concurrent snapshots are being processed by the backend, all subsequent snapshot commands scheduled for execution on the same host, should wait in the queue"
Here is the feature FS available for the review:
https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improvement
s+FS
If you have any comments/suggestions/questions on the implementation, please let me know.
-Alena.
Re: FS on cloudStack createSnapshot synchronization improvement
Posted by Alena Prokharchyk <Al...@citrix.com>.
On 10/15/12 4:27 AM, "Nitin Mehta" <Ni...@citrix.com> wrote:
>Hi Alena - Why is it that we prefer hosts on which vm is/was running for
>creating snapshots - do we see performance benefits in any way or it was
>a convenient way of choosing the host ?
Anthony is the best person to answer this question; this logic was in
place before I put in my changes. As far as I know, in VmWare case
(according to Kelven), there are less chances for the createSnapshot
command to fail when it's executed on the host where the vm resides on.
>For performance benefits can we not choose a host in the cluster which
>has the least load (in terms of create snapshot jobs or some better
>metric) so as to balance the load across the cluster.
Agree with you on that. But it would be much bigger of a change, we can
implement it later.
>I guess this would also help in first fit vm deployment algorithms to not
>overload the host and starve the create snapshot jobs ?
>
>Also can we not have different config params for
>concurrent.snapshots.threshold.perhost since the snapshot creation
>implementation is drastically different in the hypervisors so one value
>might not be the best idea here ?
Yes, you can file an enhancement for this.
>
>Thanks,
>-Nitin
>
>-----Original Message-----
>From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
>Sent: Monday, October 15, 2012 9:24 AM
>To: cloudstack-dev@incubator.apache.org; Anthony Xu
>Subject: Re: FS on cloudStack createSnapshot synchronization improvement
>
>Anthony, I implemented the threshold logic on Api Layer, in SyncQueueJob
>manager. In other words, before submitting the job for execution, we
>should know the host the job would go first to - that would be the object
>we are synchronizing on.
>For createSnapshot it's always the host where vm is 1) running on (for
>Running vm) 2) ran the last time on (for Stopped vm). Only when the
>command fails on the initial host, we retry on other hosts in cluster. So
>it would work like this:
>
>1) api call is made
>2) Before submitting the async job to the queue, we figure out the host
>id (getHostIdForSnapshotOperation method in SnapshotManagerImpl). Lets
>say, the id of the host is 1.
>3) The job is submitted with object to sync on = "host id=1".
>4) Once the job is ready to execute, it goes to snapshot manager which
>sends the command to the host id=1 first. If it fails by some reason, it
>gets resent to other host in the cluster (if exist). And in this failure
>scenario we don't do any synchronization. We've decided not to handle
>this error case because it won't happen in most of the cases.
>
>I've checked the code for other commands you've mentioned; the host is
>always picked up randomly from the list of hosts in cluster. So we can't
>apply the same logic unless we fix the code to pick up the same host on
>step 2) and step 4) without making callbacks from SnapshotManager to the
>SyncQueueManager.
>
>I would appreciate any suggestions on how to implement it.
>
>Thank you,
>Alena.
>
>From: Anthony Xu <Xu...@citrix.com>>
>Reply-To:
>"cloudstack-dev@incubator.apache.org<mailto:cloudstack-dev@incubator.apach
>e.org>"
><cloudstack-dev@incubator.apache.org<mailto:cloudstack-dev@incubator.apach
>e.org>>
>To:
>"cloudstack-dev@incubator.apache.org<mailto:cloudstack-dev@incubator.apach
>e.org>"
><cloudstack-dev@incubator.apache.org<mailto:cloudstack-dev@incubator.apach
>e.org>>
>Subject: RE: FS on cloudStack createSnapshot synchronization improvement
>
>There are several commands need this kind of threshold, e.g. Move volume,
>create template from snapshot, So this is common requirement , not only
>for createsnapshot.
>Can we add threshold mechanism in host command queue to resolve this
>issue?
>
>
>Anthony
>
>-----Original Message-----
>From: Edison Su [mailto:Edison.su@citrix.com]
>Sent: Thursday, October 11, 2012 4:42 PM
>To:
>cloudstack-dev@incubator.apache.org<mailto:cloudstack-dev@incubator.apache
>.org>
>Subject: RE: FS on cloudStack createSnapshot synchronization improvement
>
>I only have one comment:
> Can we put this snapshot improvement code out of snapshotmanager?
>
>-----Original Message-----
>From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
>Sent: Tuesday, October 09, 2012 11:51 AM
>To:
>cloudstack-dev@incubator.apache.org<mailto:cloudstack-dev@incubator.apache
>.org>
>Subject: FS on cloudStack createSnapshot synchronization improvement Hi
>All, I'm planning to introduce some changes to create snapshot behavior
>for the future cloudStack release (the changes will go to asf/master
>branch).
>The
>fix is fixing the problem described below:
>"With the current code for snapshots, cloudStack always creates snapshot
>on the host where vm is Running (for vms in Running state) or on the
>host where vm used to run the last time (for vms in Stopped state). As
>the createSnapshot commands are not synchronized on the agent side, the
>case when multiple commands are send to the backend at the same time can
>lead to the performance issues on the hypervisor side. At the end there
>is a high possibility that createSnapshot command might time out on the
>Xen side.
>The solution is to synchronize number of concurrent snapshots per host
>basis. The threshold should be configurable as the customer usually knows
>how many snapshots at a time the backend can handle.
>While the concurrent snapshots are being processed by the backend, all
>subsequent snapshot commands scheduled for execution on the same host,
>should wait in the queue"
>Here is the feature FS available for the review:
>https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improv
>e
>ment
>s+FS
>If you have any comments/suggestions/questions on the implementation,
>please let me know.
>-Alena.
>
>
>
RE: FS on cloudStack createSnapshot synchronization improvement
Posted by Nitin Mehta <Ni...@citrix.com>.
Hi Alena - Why is it that we prefer hosts on which vm is/was running for creating snapshots - do we see performance benefits in any way or it was a convenient way of choosing the host ?
For performance benefits can we not choose a host in the cluster which has the least load (in terms of create snapshot jobs or some better metric) so as to balance the load across the cluster.
I guess this would also help in first fit vm deployment algorithms to not overload the host and starve the create snapshot jobs ?
Also can we not have different config params for concurrent.snapshots.threshold.perhost since the snapshot creation implementation is drastically different in the hypervisors so one value might not be the best idea here ?
Thanks,
-Nitin
-----Original Message-----
From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
Sent: Monday, October 15, 2012 9:24 AM
To: cloudstack-dev@incubator.apache.org; Anthony Xu
Subject: Re: FS on cloudStack createSnapshot synchronization improvement
Anthony, I implemented the threshold logic on Api Layer, in SyncQueueJob manager. In other words, before submitting the job for execution, we should know the host the job would go first to - that would be the object we are synchronizing on.
For createSnapshot it's always the host where vm is 1) running on (for Running vm) 2) ran the last time on (for Stopped vm). Only when the command fails on the initial host, we retry on other hosts in cluster. So it would work like this:
1) api call is made
2) Before submitting the async job to the queue, we figure out the host id (getHostIdForSnapshotOperation method in SnapshotManagerImpl). Lets say, the id of the host is 1.
3) The job is submitted with object to sync on = "host id=1".
4) Once the job is ready to execute, it goes to snapshot manager which sends the command to the host id=1 first. If it fails by some reason, it gets resent to other host in the cluster (if exist). And in this failure scenario we don't do any synchronization. We've decided not to handle this error case because it won't happen in most of the cases.
I've checked the code for other commands you've mentioned; the host is always picked up randomly from the list of hosts in cluster. So we can't apply the same logic unless we fix the code to pick up the same host on step 2) and step 4) without making callbacks from SnapshotManager to the SyncQueueManager.
I would appreciate any suggestions on how to implement it.
Thank you,
Alena.
From: Anthony Xu <Xu...@citrix.com>>
Reply-To: "cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>" <cl...@incubator.apache.org>>
To: "cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>" <cl...@incubator.apache.org>>
Subject: RE: FS on cloudStack createSnapshot synchronization improvement
There are several commands need this kind of threshold, e.g. Move volume, create template from snapshot, So this is common requirement , not only for createsnapshot.
Can we add threshold mechanism in host command queue to resolve this issue?
Anthony
-----Original Message-----
From: Edison Su [mailto:Edison.su@citrix.com]
Sent: Thursday, October 11, 2012 4:42 PM
To: cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>
Subject: RE: FS on cloudStack createSnapshot synchronization improvement
I only have one comment:
Can we put this snapshot improvement code out of snapshotmanager?
-----Original Message-----
From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
Sent: Tuesday, October 09, 2012 11:51 AM
To: cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>
Subject: FS on cloudStack createSnapshot synchronization improvement Hi All, I'm planning to introduce some changes to create snapshot behavior for the future cloudStack release (the changes will go to asf/master branch).
The
fix is fixing the problem described below:
"With the current code for snapshots, cloudStack always creates snapshot on the host where vm is Running (for vms in Running state) or on the host where vm used to run the last time (for vms in Stopped state). As the createSnapshot commands are not synchronized on the agent side, the case when multiple commands are send to the backend at the same time can lead to the performance issues on the hypervisor side. At the end there is a high possibility that createSnapshot command might time out on the Xen side.
The solution is to synchronize number of concurrent snapshots per host basis. The threshold should be configurable as the customer usually knows how many snapshots at a time the backend can handle.
While the concurrent snapshots are being processed by the backend, all subsequent snapshot commands scheduled for execution on the same host, should wait in the queue"
Here is the feature FS available for the review:
https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improv
e
ment
s+FS
If you have any comments/suggestions/questions on the implementation, please let me know.
-Alena.
Re: FS on cloudStack createSnapshot synchronization improvement
Posted by Alena Prokharchyk <Al...@citrix.com>.
Anthony, I implemented the threshold logic on Api Layer, in SyncQueueJob manager. In other words, before submitting the job for execution, we should know the host the job would go first to – that would be the object we are synchronizing on.
For createSnapshot it's always the host where vm is 1) running on (for Running vm) 2) ran the last time on (for Stopped vm). Only when the command fails on the initial host, we retry on other hosts in cluster. So it would work like this:
1) api call is made
2) Before submitting the async job to the queue, we figure out the host id (getHostIdForSnapshotOperation method in SnapshotManagerImpl). Lets say, the id of the host is 1.
3) The job is submitted with object to sync on = "host id=1".
4) Once the job is ready to execute, it goes to snapshot manager which sends the command to the host id=1 first. If it fails by some reason, it gets resent to other host in the cluster (if exist). And in this failure scenario we don't do any synchronization. We've decided not to handle this error case because it won't happen in most of the cases.
I've checked the code for other commands you've mentioned; the host is always picked up randomly from the list of hosts in cluster. So we can't apply the same logic unless we fix the code to pick up the same host on step 2) and step 4) without making callbacks from SnapshotManager to the SyncQueueManager.
I would appreciate any suggestions on how to implement it.
Thank you,
Alena.
From: Anthony Xu <Xu...@citrix.com>>
Reply-To: "cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>" <cl...@incubator.apache.org>>
To: "cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>" <cl...@incubator.apache.org>>
Subject: RE: FS on cloudStack createSnapshot synchronization improvement
There are several commands need this kind of threshold, e.g. Move volume, create template from snapshot,
So this is common requirement , not only for createsnapshot.
Can we add threshold mechanism in host command queue to resolve this issue?
Anthony
-----Original Message-----
From: Edison Su [mailto:Edison.su@citrix.com]
Sent: Thursday, October 11, 2012 4:42 PM
To: cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>
Subject: RE: FS on cloudStack createSnapshot synchronization improvement
I only have one comment:
Can we put this snapshot improvement code out of snapshotmanager?
-----Original Message-----
From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
Sent: Tuesday, October 09, 2012 11:51 AM
To: cloudstack-dev@incubator.apache.org<ma...@incubator.apache.org>
Subject: FS on cloudStack createSnapshot synchronization improvement
Hi All,
I'm planning to introduce some changes to create snapshot behavior for
the future cloudStack release (the changes will go to asf/master
branch).
The
fix is fixing the problem described below:
"With the current code for snapshots, cloudStack always creates
snapshot on the host where vm is Running (for vms in Running state)
or on the host where vm used to run the last time (for vms in Stopped
state). As the createSnapshot commands are not synchronized on the
agent side, the case when multiple commands are send to the backend
at the same time can lead to the performance issues on the hypervisor
side. At the end there is a high possibility that createSnapshot
command might time out on the Xen side.
The solution is to synchronize number of concurrent snapshots per
host basis. The threshold should be configurable as the customer
usually knows how many snapshots at a time the backend can handle.
While the concurrent snapshots are being processed by the backend,
all subsequent snapshot commands scheduled for execution on the same
host, should wait in the queue"
Here is the feature FS available for the review:
https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improv
e
ment
s+FS
If you have any comments/suggestions/questions on the implementation,
please let me know.
-Alena.
RE: FS on cloudStack createSnapshot synchronization improvement
Posted by Anthony Xu <Xu...@citrix.com>.
There are several commands need this kind of threshold, e.g. Move volume, create template from snapshot,
So this is common requirement , not only for createsnapshot.
Can we add threshold mechanism in host command queue to resolve this issue?
Anthony
-----Original Message-----
From: Edison Su [mailto:Edison.su@citrix.com]
Sent: Thursday, October 11, 2012 4:42 PM
To: cloudstack-dev@incubator.apache.org
Subject: RE: FS on cloudStack createSnapshot synchronization improvement
I only have one comment:
Can we put this snapshot improvement code out of snapshotmanager?
> -----Original Message-----
> From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
> Sent: Tuesday, October 09, 2012 11:51 AM
> To: cloudstack-dev@incubator.apache.org
> Subject: FS on cloudStack createSnapshot synchronization improvement
>
> Hi All,
>
> I'm planning to introduce some changes to create snapshot behavior for
> the future cloudStack release (the changes will go to asf/master
> branch).
> The
> fix is fixing the problem described below:
>
> "With the current code for snapshots, cloudStack always creates
> snapshot on the host where vm is Running (for vms in Running state)
> or on the host where vm used to run the last time (for vms in Stopped
> state). As the createSnapshot commands are not synchronized on the
> agent side, the case when multiple commands are send to the backend
> at the same time can lead to the performance issues on the hypervisor
> side. At the end there is a high possibility that createSnapshot
> command might time out on the Xen side.
> The solution is to synchronize number of concurrent snapshots per
> host basis. The threshold should be configurable as the customer
> usually knows how many snapshots at a time the backend can handle.
> While the concurrent snapshots are being processed by the backend,
> all subsequent snapshot commands scheduled for execution on the same
> host, should wait in the queue"
>
>
> Here is the feature FS available for the review:
>
> https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improv
> e
> ment
> s+FS
>
> If you have any comments/suggestions/questions on the implementation,
> please let me know.
>
>
> -Alena.
Re: FS on cloudStack createSnapshot synchronization improvement
Posted by Alena Prokharchyk <Al...@citrix.com>.
Its out of the snapshotManager. Synchronization is being controlled by the
code SyncQueueManagerImpl. Number of entries the object-we-sync-on (HOST)
can handle, is being passed to the syncQueueManagerImpl when we
createSnapshot async job is submitted.
I did just one change in the SnapshotManager - extracted the method from
existing code. The method returns the destination host where the
createSnapshot command will be sent to.
-Alena.
On 10/11/12 4:41 PM, "Edison Su" <Ed...@citrix.com> wrote:
>I only have one comment:
> Can we put this snapshot improvement code out of snapshotmanager?
>
>> -----Original Message-----
>> From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
>> Sent: Tuesday, October 09, 2012 11:51 AM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: FS on cloudStack createSnapshot synchronization improvement
>>
>> Hi All,
>>
>> I'm planning to introduce some changes to create snapshot behavior for
>> the
>> future cloudStack release (the changes will go to asf/master branch).
>> The
>> fix is fixing the problem described below:
>>
>> "With the current code for snapshots, cloudStack always creates
>> snapshot
>> on the host where vm is Running (for vms in Running state) or on the
>> host
>> where vm used to run the last time (for vms in Stopped state). As the
>> createSnapshot commands are not synchronized on the agent side, the
>> case
>> when multiple commands are send to the backend at the same time can
>> lead
>> to the performance issues on the hypervisor side. At the end there is
>> a
>> high possibility that createSnapshot command might time out on the Xen
>> side.
>> The solution is to synchronize number of concurrent snapshots per host
>> basis. The threshold should be configurable as the customer usually
>> knows
>> how many snapshots at a time the backend can handle.
>> While the concurrent snapshots are being processed by the backend, all
>> subsequent snapshot commands scheduled for execution on the same host,
>> should wait in the queue"
>>
>>
>> Here is the feature FS available for the review:
>>
>> https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improve
>> ment
>> s+FS
>>
>> If you have any comments/suggestions/questions on the implementation,
>> please let me know.
>>
>>
>> -Alena.
>
>
RE: FS on cloudStack createSnapshot synchronization improvement
Posted by Edison Su <Ed...@citrix.com>.
I only have one comment:
Can we put this snapshot improvement code out of snapshotmanager?
> -----Original Message-----
> From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
> Sent: Tuesday, October 09, 2012 11:51 AM
> To: cloudstack-dev@incubator.apache.org
> Subject: FS on cloudStack createSnapshot synchronization improvement
>
> Hi All,
>
> I'm planning to introduce some changes to create snapshot behavior for
> the
> future cloudStack release (the changes will go to asf/master branch).
> The
> fix is fixing the problem described below:
>
> "With the current code for snapshots, cloudStack always creates
> snapshot
> on the host where vm is Running (for vms in Running state) or on the
> host
> where vm used to run the last time (for vms in Stopped state). As the
> createSnapshot commands are not synchronized on the agent side, the
> case
> when multiple commands are send to the backend at the same time can
> lead
> to the performance issues on the hypervisor side. At the end there is
> a
> high possibility that createSnapshot command might time out on the Xen
> side.
> The solution is to synchronize number of concurrent snapshots per host
> basis. The threshold should be configurable as the customer usually
> knows
> how many snapshots at a time the backend can handle.
> While the concurrent snapshots are being processed by the backend, all
> subsequent snapshot commands scheduled for execution on the same host,
> should wait in the queue"
>
>
> Here is the feature FS available for the review:
>
> https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improve
> ment
> s+FS
>
> If you have any comments/suggestions/questions on the implementation,
> please let me know.
>
>
> -Alena.