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https://issues.apache.org/jira/browse/CLOUDSTACK-7857?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14209545#comment-14209545
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Joris van Lieshout commented on CLOUDSTACK-7857:
------------------------------------------------
Hi Rohit, I did some digging around in the XenCenter code and found a possible
solution there. But there is a challenge I think. The overhead is dynamic
based on the instances running on the host, and, at the moment, ACS calculates
this overhead at host thread startup.
This is what I found in the XenCenter code:
https://github.com/xenserver/xenadmin/blob/a0d31920c5ac62eda9713228043a834ba7829986/XenModel/XenAPI-Extensions/Host.cs#L1071
======
public long xen_memory_calc
{
get
{
if (!Helpers.MidnightRideOrGreater(Connection))
{
Host_metrics host_metrics =
Connection.Resolve(this.metrics);
if (host_metrics == null)
return 0;
long totalused = 0;
foreach (VM vm in Connection.ResolveAll(resident_VMs))
{
VM_metrics vmMetrics =
vm.Connection.Resolve(vm.metrics);
if (vmMetrics != null)
totalused += vmMetrics.memory_actual;
}
return host_metrics.memory_total - totalused -
host_metrics.memory_free;
}
long xen_mem = memory_overhead;
foreach (VM vm in Connection.ResolveAll(resident_VMs))
{
xen_mem += vm.memory_overhead;
if (vm.is_control_domain)
{
VM_metrics vmMetrics =
vm.Connection.Resolve(vm.metrics);
if (vmMetrics != null)
xen_mem += vmMetrics.memory_actual;
}
}
return xen_mem;
}
}
=====
We can skip the first part because, if I'm not mistaking, ACS only supports
XS5.6 and up. XS5.6 = MidnightRide
In short the formula is something like this: xen_mem = host_memory_overhead +
residentVMs_memory_overhead + dom0_memory_actual
Here is a list of xe commands that will get you the correct numbers to
summarize.
host_mem_overhead
xe host-list name-label=$HOSTNAME params=memory-overhead --minimal
residentVMs_memory_overhead
xe vm-list resident-on=$(xe host-list name-label=$HOSTNAME --minimal)
params=memory-overhead --minimal
dom0_memory_actual
xe vm-list resident-on=$(xe host-list name-label=$HOSTNAME --minimal)
is-control-domain=true params=memory-actual --minimal
> CitrixResourceBase wrongly calculates total memory on hosts with a lot of
> memory and large Dom0
> -----------------------------------------------------------------------------------------------
>
> Key: CLOUDSTACK-7857
> URL: https://issues.apache.org/jira/browse/CLOUDSTACK-7857
> Project: CloudStack
> Issue Type: Bug
> Security Level: Public(Anyone can view this level - this is the
> default.)
> Affects Versions: Future, 4.3.0, 4.4.0, 4.5.0, 4.3.1, 4.4.1, 4.6.0
> Reporter: Joris van Lieshout
> Priority: Blocker
>
> We have hosts with 256GB memory and 4GB dom0. During startup ACS calculates
> available memory using this formula:
> CitrixResourceBase.java
> protected void fillHostInfo
> ram = (long) ((ram - dom0Ram - _xs_memory_used) *
> _xs_virtualization_factor);
> In our situation:
> ram = 274841497600
> dom0Ram = 4269801472
> _xs_memory_used = 128 * 1024 * 1024L = 134217728
> _xs_virtualization_factor = 63.0/64.0 = 0,984375
> (274841497600 - 4269801472 - 134217728) * 0,984375 = 266211892800
> This is in fact not the actual amount of memory available for instances. The
> difference in our situation is a little less then 1GB. On this particular
> hypervisor Dom0+Xen uses about 9GB.
> As the comment above the definition of XsMemoryUsed allready stated it's time
> to review this logic.
> "//Hypervisor specific params with generic value, may need to be overridden
> for specific versions"
> The effect of this bug is that when you put a hypervisor in maintenance it
> might try to move instances (usually small instances (<1GB)) to a host that
> in fact does not have enought free memory.
> This exception is thrown:
> ERROR [c.c.h.HighAvailabilityManagerImpl] (HA-Worker-3:ctx-09aca6e9
> work-8981) Terminating HAWork[8981-Migration-4482-Running-Migrating]
> com.cloud.utils.exception.CloudRuntimeException: Unable to migrate due to
> Catch Exception com.cloud.utils.exception.CloudRuntimeException: Migration
> failed due to com.cloud.utils.exception.CloudRuntim
> eException: Unable to migrate VM(r-4482-VM) from
> host(6805d06c-4d5b-4438-a245-7915e93041d9) due to Task failed! Task record:
> uuid: 645b63c8-1426-b412-7b6a-13d61ee7ab2e
> nameLabel: Async.VM.pool_migrate
> nameDescription:
> allowedOperations: []
> currentOperations: {}
> created: Thu Nov 06 13:44:14 CET 2014
> finished: Thu Nov 06 13:44:14 CET 2014
> status: failure
> residentOn: com.xensource.xenapi.Host@b42882c6
> progress: 1.0
> type: <none/>
> result:
> errorInfo: [HOST_NOT_ENOUGH_FREE_MEMORY, 272629760, 263131136]
> otherConfig: {}
> subtaskOf: com.xensource.xenapi.Task@aaf13f6f
> subtasks: []
> at
> com.cloud.vm.VirtualMachineManagerImpl.migrate(VirtualMachineManagerImpl.java:1840)
> at
> com.cloud.vm.VirtualMachineManagerImpl.migrateAway(VirtualMachineManagerImpl.java:2214)
> at
> com.cloud.ha.HighAvailabilityManagerImpl.migrate(HighAvailabilityManagerImpl.java:610)
> at
> com.cloud.ha.HighAvailabilityManagerImpl$WorkerThread.runWithContext(HighAvailabilityManagerImpl.java:865)
> at
> com.cloud.ha.HighAvailabilityManagerImpl$WorkerThread.access$000(HighAvailabilityManagerImpl.java:822)
> at
> com.cloud.ha.HighAvailabilityManagerImpl$WorkerThread$1.run(HighAvailabilityManagerImpl.java:834)
> at
> org.apache.cloudstack.managed.context.impl.DefaultManagedContext$1.call(DefaultManagedContext.java:56)
> at
> org.apache.cloudstack.managed.context.impl.DefaultManagedContext.callWithContext(DefaultManagedContext.java:103)
> at
> org.apache.cloudstack.managed.context.impl.DefaultManagedContext.runWithContext(DefaultManagedContext.java:53)
> at
> com.cloud.ha.HighAvailabilityManagerImpl$WorkerThread.run(HighAvailabilityManagerImpl.java:831)
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