Prachi,
I am planning to add the following code in findSuitablePoolsForVolumes()
method. If the VM has a local disk and the cluster doesn't have a local pool
then the cluster will be added to avoid set. Let me know if you see any issues
with this.
if (useLocalStorage) {
List<StoragePoolVO> allPoolsInCluster =
_storagePoolDao.findPoolsByTags(plan.getDataCenterId(), plan.getPodId(),
plan.getClusterId(), null);
boolean localStoragePoolExists = false;
for (StoragePoolVO pool : allPoolsInCluster) {
if (pool.isLocal()) {
localStoragePoolExists = true;
break;
}
}
if (!localStoragePoolExists) {
avoid.addCluster(plan.getClusterId());
}
}
-Koushik
On 17-Oct-2013, at 3:21 AM, Prachi Damle
<prachi.da...@citrix.com<mailto:prachi.da...@citrix.com>> wrote:
-----Original Message-----
From: Koushik Das [mailto:koushik....@citrix.com<http://citrix.com>]
Sent: Wednesday, October 16, 2013 5:21 AM
To: <dev@cloudstack.apache.org<mailto:dev@cloudstack.apache.org>>
Subject: Re: Possible bug in DeploymentPlanner?
On 16-Oct-2013, at 3:12 AM, Prachi Damle
<prachi.da...@citrix.com<mailto:prachi.da...@citrix.com>> wrote:
-----Original Message-----
From: Koushik Das [mailto:koushik....@citrix.com<http://citrix.com>]
Sent: Tuesday, October 15, 2013 11:43 AM
To: <dev@cloudstack.apache.org<mailto:dev@cloudstack.apache.org>>
Subject: Re: Possible bug in DeploymentPlanner?
Thanks for the explanation Prachi.
Here is one issue I see with what you explained below. If an allocator is not
suppose to handle a particular scenario how should it deal with the avoid set.
Should it put all available pools in the avoid set. In that case subsequent
allocators won't get a chance to do anything as all pools are in avoid set. If
more than one allocator can operate on a particular pool then the situation
becomes tricky.
To give an example, if there is a request for volume on shared storage and
first allocator to get called is the local allocator. Since it is not going to
handle this case it will return empty/null list. Now should it put all the
other shared pools in avoid set or only the local pools in avoid set? Similarly
if the request is for a local volume and the request first goes to zone or
cluster-wide storage allocator what should be there in the avoid set?
[Prachi] I see the bug you are thinking about - deploymentPlanningManager ::
canAvoidCluster is only checking the shared storages and thus does not put the
cluster in avoid set in case the local storage is not a match for the host.
I think the storage allocators should put the resources not considered, in
avoid set, that are within their scope. Also they should do so only when they
are supposed to handle the request. Thus local allocator sees only local pools,
so it should place them into avoid set if not considered and only when this
allocator is supposed to handle the scenario. While the zone-wide/cluster-wide
should set those within their scope.
Also, the allocators have a defined order in which they get invoked and we need
to maintain the order defined in the componentContext.xml
Now to solve the bug, the deploymentPlanningManager :: canAvoidCluster needs
to consider which scenario applies for the given vmprofile - i.e whether its
local storage or shared to correctly figure out if cluster can be avoided by
considering applicable pools only.
Does this work fine for your scenario?
[Koushik] Not sure if canAvoidCluster() is the right place. Shared and local
pools can belong to the same cluster, so the cluster cannot be put in avoid
set. Only the pools needs to be selectively added to avoid set.
[Prachi] Allocators add the resources to avoid set and then DPM can figure out
if a cluster is done searching looking at the avoid set, so that the planner
need not choose that cluster on next try.
So two changes are needed: Storage Allocators should set resources in avoid set
within their scope and DPM should check if a cluster is done accordingly.
Can you let me know the specific bug you want to change allocators for? I will
add the above change in a separate ticket if already not done for your bug.
On 15-Oct-2013, at 11:31 PM, Prachi Damle
<prachi.da...@citrix.com<mailto:prachi.da...@citrix.com>>
wrote:
Koushik,
The deployment planning process is divided between DeploymentPlanners and
Allocators. The planners are supposed to feed a list of clusters the allocators
should look into to find a potential destination. While the allocators should
provide a avoid set back to the planners consisting of any resource not
considered.
Reasoning how the planners work:
Planners can set/reset clusters into avoid set depending on the heuristics they
implement and the order in which they want the clusters to be traversed.
When all options of the planner are exhausted they should return an empty
cluster list halting the search.
What should the allocators do?
Iterate over the given cluster list and in each cluster find out suitable
resources - all other resources not considered AND not suitable MUST be added
to the avoid set so that the planners get the correct avoid input.
This is necessary for the logic to not enter an infinite loop.
As you see, only planners can halt the search process by referring to the avoid
set provided by the allocators. If you see any case not following this, that
needs to be fixed.
Also, I do think in general it will be safe to add a configurable retry limit
on this loop to have control in case any new logic in allocators don't follow
this reasoning. I will add that limit.
Thanks,
Prachi
-----Original Message-----
From: Koushik Das [mailto:koushik....@citrix.com<http://citrix.com>]
Sent: Tuesday, October 15, 2013 9:19 AM
To: <dev@cloudstack.apache.org<mailto:dev@cloudstack.apache.org>>
Subject: Possible bug in DeploymentPlanner?
I was making some changes in the storage pool allocators related to some bug
fix and came across this code snippet in planDeplyment() method of
DeploymentPlanningManagerImpl.java.
In this if the checkClustersforDestination() returns null and the 'avoids'
parameter is not correctly updated (one such place can be the storage
allocators) then the while loop will never terminate. Is there any assumption
about how the 'avoids' parameter needs to be updated? From the code it is not
very intuitive. I saw some places in the storage pool allocators where this
will not get updated.
Wanted to understand the reason for doing it this way? Can the while (true)
condition be replaced with something more intuitive?
while (true) {
if (planner instanceof DeploymentClusterPlanner) {
ExcludeList plannerAvoidInput = new
ExcludeList(avoids.getDataCentersToAvoid(),
avoids.getPodsToAvoid(), avoids.getClustersToAvoid(),
avoids.getHostsToAvoid(),
avoids.getPoolsToAvoid());
clusterList = ((DeploymentClusterPlanner)
planner).orderClusters(vmProfile, plan, avoids);
if (clusterList != null && !clusterList.isEmpty()) {
// planner refactoring. call allocators to list hosts
ExcludeList plannerAvoidOutput = new
ExcludeList(avoids.getDataCentersToAvoid(),
avoids.getPodsToAvoid(),
avoids.getClustersToAvoid(), avoids.getHostsToAvoid(),
avoids.getPoolsToAvoid());
resetAvoidSet(plannerAvoidOutput, plannerAvoidInput);
dest = checkClustersforDestination(clusterList, vmProfile,
plan, avoids, dc,
getPlannerUsage(planner, vmProfile, plan, avoids),
plannerAvoidOutput);
if (dest != null) {
return dest;
}
// reset the avoid input to the planners
resetAvoidSet(avoids, plannerAvoidOutput);
} else {
return null;
}
} else {
............
............
}
}
