Test scale_vm_vm needs fixing for XenServer/XCP-ng

[andrijapanicsb]

Running Marvin test test_scale_vm (test_01_scale_vm) on any version of XenServer/XCP-ng fails due to:

2020-07-24 21:17:10,550 ERROR [c.c.v.VirtualMachineManagerImpl] (Work-Job-Executor-137:ctx-a555852b job-1829/job-1830 ctx-ac21684e) (logid:59af6655) Unable to scale vm due to Catch exception com.cloud.utils.exception.CloudRuntimeException when scaling VM:i-160-204-VM due to com.cloud.utils.exception.CloudRuntimeException: Cannot scale up the vm because of memory constraint violation: 0 <= memory-static-min(268435456) <= memory-dynamic-min(536870912) <= memory-dynamic-max(536870912) <= memory-static-max(268435456)
For more log information, see any of the failed tests from PR #4068

[andrijapanicsb]

cc @DaanHoogland @Spaceman1984

(reminds of the similar issue in VMware where the calculated target RAM size was 0, so a divide by 0 failed etc...)

[yadvr]

cc @shwstppr

[DaanHoogland]

cc @DaanHoogland @Spaceman1984

(reminds of the similar issue in VMware where the calculated target RAM size was 0, so a divide by 0 failed etc...)

It rings no bell @andrijapanicsb . also ram being 0 w/should not lead to devide by zero as deviding something by the amount of ram makes no sense to me. Any more hints? @rhtyd are you familiar with the issue?

[yadvr]

Nope I'm not that's why I pinged @shwstppr

[yadvr]

cc @Spaceman1984 can you look into this after the cluster/deploying planning investigation, thnx

[shwstppr]

@rhtyd @DaanHoogland @Spaceman1984
Dynamic scaling for running VM is failing here,
https://github.com/apache/cloudstack/blob/master/plugins/hypervisors/xenserver/src/main/java/com/cloud/hypervisor/xenserver/resource/CitrixResourceBase.java#L4606

I checked with xcp-ng and tried to change compute offering for a Macchinina VM (memory 512mb to 768mb).
memory-static-min and memory-static-max for VM remains the same as initial offering value (512mb in my case) and hence the check fails. I checked with hypervisor itself.

[12:50 xcp-ng-monkeybox ~]# xe vm-param-get param-name=memory-static-min uuid=4af04114-a83b-c8ba-1002-005bb11c4b35
536870912
[12:51 xcp-ng-monkeybox ~]# xe vm-param-get param-name=memory-static-max uuid=4af04114-a83b-c8ba-1002-005bb11c4b35
536870912

When I update these values to some appropriate range (512-1024 as I wanted to scale my VM's memory from 512 to 768mb) dynamic scaling works fine.

[12:51 xcp-ng-monkeybox ~]# xe vm-shutdown uuid=4af04114-a83b-c8ba-1002-005bb11c4b35
[12:51 xcp-ng-monkeybox ~]# xe vm-memory-static-range-set uuid=4af04114-a83b-c8ba-1002-005bb11c4b35 min=536870912 max=1073741824
[12:51 xcp-ng-monkeybox ~]# xe vm-start uuid=4af04114-a83b-c8ba-1002-005bb11c4b35
[12:51 xcp-ng-monkeybox ~]# xe vm-param-get param-name=memory-static-min uuid=4af04114-a83b-c8ba-1002-005bb11c4b35
536870912
[12:51 xcp-ng-monkeybox ~]# xe vm-param-get param-name=memory-static-max uuid=4af04114-a83b-c8ba-1002-005bb11c4b35
1073741824

So, should we be setting this memory-static range for the VM during deployment or before actual scaling? I also checked with a CentOS7 VM so this doesn't seem to a problem with guest OS.
https://docs.citrix.com/en-us/citrix-hypervisor/vms/vm-memory.html#memory-constraints

[yadvr]

@shwstppr can you discuss this with @andrijapanicsb if it's a hypervisor limitation to scale for a running VM then there's hardly anything we can do

[andrijapanicsb]

static min/max is set in a silly way when a VM is created - and that is done by ACS as far as I can remember.
Static min needs to be set to i.e. 1MB or 16 MB or some very low value that we will never reach, and same goes for the static max value. Beside that, the template should be marked as Dynamically Scallable, otherwise it won't work.

i.e. the"dynamic values" (min/max) can be changed in the range defined by statix min/max.