[ovirt-users] Recommended setup for a FC based storage domain

[combuster]

Bad news happens only when running a VM for the first time, if it helps...

On 06/09/2014 01:30 PM, combuster wrote:
> OK, I have good news and bad news :)
>
> Good news is that I can run different VM's on different nodes when all 
> of their drives are on FC Storage domain. I don't think that all of 
> I/O is running through SPM, but I need to test that. Simply put, for 
> every virtual disk that you create on the shared fc storage domain, 
> ovirt will present that vdisk only to the node wich is running the VM 
> itself. They all can see domain infrastructure (inbox,outbox,metadata) 
> but the LV for the virtual disk itself for that VM is visible only to 
> the node that is running that particular VM. There is no limitation 
> (except for the free space on the storage).
>
> Bad news!
>
> I can create the virtual disk on the fc storage for a vm, but when I 
> start the VM itself, node wich hosts the VM that I'm starting is going 
> non-operational, and quickly goes up again (ilo fencing agent checks 
> if the node is ok and bring it back up). During that time, vm starts 
> on another node (Default Host parameter was ignored - assigned Host 
> was not available). I can manualy migrate it later to the intended 
> node, that works. Lucky me, on two nodes (of the four) in the cluster, 
> there were no vm's running (i tried this on both, with two different 
> vm's created from scratch and i got the same result.
>
> I've killed everything above WARNING because it was killing the 
> performance of the cluster. vdsm.log :
>
> [code]
> Thread-305::WARNING::2014-06-09 
> 12:15:53,236::persistentDict::256::Storage.PersistentDict::(refresh) 
> data has no embedded checksum - trust it as it is
> 55809e40-ccf3-4f7c-aeec-802bc1c326a7::WARNING::2014-06-09 
> 12:17:25,013::utils::129::root::(rmFile) File: 
> /rhev/data-center/a0500f5c-e8d9-42f1-8f04-15b23514c8ed/55338570-e537-412b-97a9-635eea1ecb10/images/90659ad8-bd90-4a0a-bb4e-7c6afe90e925/242a1bce-a434-4246-ad24-b62f99c03a05 
> already removed
> 55809e40-ccf3-4f7c-aeec-802bc1c326a7::WARNING::2014-06-09 
> 12:17:25,074::blockSD::761::Storage.StorageDomain::(_getOccupiedMetadataSlots) 
> Could not find mapping for lv 
> 55338570-e537-412b-97a9-635eea1ecb10/242a1bce-a434-4246-ad24-b62f99c03a05
> Thread-305::WARNING::2014-06-09 
> 12:20:54,341::persistentDict::256::Storage.PersistentDict::(refresh) 
> data has no embedded checksum - trust it as it is
> Thread-305::WARNING::2014-06-09 
> 12:25:55,378::persistentDict::256::Storage.PersistentDict::(refresh) 
> data has no embedded checksum - trust it as it is
> Thread-305::WARNING::2014-06-09 
> 12:30:56,424::persistentDict::256::Storage.PersistentDict::(refresh) 
> data has no embedded checksum - trust it as it is
> Thread-1857::WARNING::2014-06-09 
> 12:32:45,639::libvirtconnection::116::root::(wrapper) connection to 
> libvirt broken. ecode: 1 edom: 7
> Thread-1857::CRITICAL::2014-06-09 
> 12:32:45,640::libvirtconnection::118::root::(wrapper) taking calling 
> process down.
> Thread-17704::WARNING::2014-06-09 
> 12:32:48,009::libvirtconnection::116::root::(wrapper) connection to 
> libvirt broken. ecode: 1 edom: 7
> Thread-17704::CRITICAL::2014-06-09 
> 12:32:48,013::libvirtconnection::118::root::(wrapper) taking calling 
> process down.
> Thread-17704::ERROR::2014-06-09 
> 12:32:48,018::vm::2285::vm.Vm::(_startUnderlyingVm) 
> vmId=`2bee9d79-b8d1-4a5a-a4f7-8092d1c803d9`::The vm start process failed
> Traceback (most recent call last):
>   File "/usr/share/vdsm/vm.py", line 2245, in _startUnderlyingVm
>     self._run()
>   File "/usr/share/vdsm/vm.py", line 3185, in _run
>     self._connection.createXML(domxml, flags),
>   File "/usr/lib64/python2.6/site-packages/vdsm/libvirtconnection.py", 
> line 110, in wrapper
>     __connections.get(id(target)).pingLibvirt()
>   File "/usr/lib64/python2.6/site-packages/libvirt.py", line 3389, in 
> getLibVersion
>     if ret == -1: raise libvirtError ('virConnectGetLibVersion() 
> failed', conn=self)
> libvirtError: internal error client socket is closed
> Thread-1857::WARNING::2014-06-09 
> 12:32:50,673::vm::1963::vm.Vm::(_set_lastStatus) 
> vmId=`2bee9d79-b8d1-4a5a-a4f7-8092d1c803d9`::trying to set state to 
> Powering down when already Down
> Thread-1857::WARNING::2014-06-09 
> 12:32:50,815::utils::129::root::(rmFile) File: 
> /var/lib/libvirt/qemu/channels/2bee9d79-b8d1-4a5a-a4f7-8092d1c803d9.com.redhat.rhevm.vdsm 
> already removed
> Thread-1857::WARNING::2014-06-09 
> 12:32:50,816::utils::129::root::(rmFile) File: 
> /var/lib/libvirt/qemu/channels/2bee9d79-b8d1-4a5a-a4f7-8092d1c803d9.org.qemu.guest_agent.0 
> already removed
> MainThread::WARNING::2014-06-09 
> 12:33:03,770::fileUtils::167::Storage.fileUtils::(createdir) Dir 
> /rhev/data-center/mnt already exists
> MainThread::WARNING::2014-06-09 
> 12:33:05,738::clientIF::181::vds::(_prepareBindings) Unable to load 
> the json rpc server module. Please make sure it is installed.
> storageRefresh::WARNING::2014-06-09 
> 12:33:06,133::fileUtils::167::Storage.fileUtils::(createdir) Dir 
> /rhev/data-center/hsm-tasks already exists
> Thread-35::ERROR::2014-06-09 
> 12:33:08,375::sdc::137::Storage.StorageDomainCache::(_findDomain) 
> looking for unfetched domain 55338570-e537-412b-97a9-635eea1ecb10
> Thread-35::ERROR::2014-06-09 
> 12:33:08,413::sdc::154::Storage.StorageDomainCache::(_findUnfetchedDomain) 
> looking for domain 55338570-e537-412b-97a9-635eea1ecb10
> Thread-13::WARNING::2014-06-09 
> 12:33:08,417::fileUtils::167::Storage.fileUtils::(createdir) Dir 
> /rhev/data-center/a0500f5c-e8d9-42f1-8f04-15b23514c8ed already exists
> [/code]
>
> libvirt breaks and I guess that it would bring down all of VM's if 
> there were any on that node.
>
> Anybody have an idea why this happens ?
>
> TIA,
>
> Ivan
>
> On 06/02/2014 04:38 PM, combuster at archlinux.us wrote:
>> One word of caution so far, when exporting any vm, the node that acts as SPM
>> is stressed out to the max. I releived the stress by a certain margin with
>> lowering libvirtd and vdsm log levels to WARNING. That shortened out the
>> export procedure by at least five times. But vdsm process on the SPM node  is
>> still with high cpu usage so it's best that the SPM node should be left with a
>> decent CPU time amount to spare. Also, export of VM's with high vdisk capacity
>> and thin provisioning enabled (let's say 14GB used of 100GB defined) took
>> around 50min over a 10Gb ethernet interface to a 1Gb export NAS device that
>> was not stressed out at all by other processes. When I did that export with
>> debug log levels it took 5hrs :(
>>
>> So lowering log levels is a must in production enviroment. I've deleted the
>> lun that I exported on the storage (removed it first from ovirt) and for the
>> next weekend I am planing to add a new one, export it again on all the nodes
>> and start a few fresh vm installations. Things I'm going to look for are
>> partition alignment and running them from different nodes in the cluster at
>> the same time. I just hope that not all I/O is going to pass through the SPM,
>> this is the one thing that bothers me the most.
>>   
>> I'll report back on these results next week, but if anyone has experience with
>> this kind of things or can point  to some documentation would be great.
>>
>> On Monday, 2. June 2014. 18.51.52 you wrote:
>>> I'm curious to hear what other comments arise, as we're analyzing a
>>> production setup shortly.
>>>
>>> On Sun, Jun 1, 2014 at 10:11 PM,<combuster at archlinux.us>  wrote:
>>>> I need to scratch gluster off because setup is based on CentOS 6.5, so
>>>> essential prerequisites like qemu 1.3 and libvirt 1.0.1 are not met.
>>> Gluster would still work with EL6, afaik it just won't use libgfapi and
>>> instead use just a standard mount.
>>>
>>>> Any info regarding FC storage domain would be appreciated though.
>>>>
>>>> Thanks
>>>>
>>>> Ivan
>>>>
>>>> On Sunday, 1. June 2014. 11.44.33combuster at archlinux.us  wrote:
>>>>> Hi,
>>>>>
>>>>> I have a 4 node cluster setup and my storage options right now are a FC
>>>>> based storage, one partition per node on a local drive (~200GB each) and
>>>>> a
>>>>> NFS based NAS device. I want to setup export and ISO domain on the NAS
>>>>> and
>>>>> there are no issues or questions regarding those two. I wasn't aware of
>>>>> any
>>>>> other options at the time for utilizing a local storage (since this is a
>>>>> shared based datacenter) so I exported a directory from each partition
>>>>> via
>>>>> NFS and it works. But I am little in the dark with the following:
>>>>>
>>>>> 1. Are there any advantages for switching from NFS based local storage to
>>>>> a
>>>>> Gluster based domain with blocks for each partition. I guess it can be
>>>>> only
>>>>> performance wise but maybe I'm wrong. If there are advantages, are there
>>>>> any tips regarding xfs mount options etc ?
>>>>>
>>>>> 2. I've created a volume on the FC based storage and exported it to all
>>>>> of
>>>>> the nodes in the cluster on the storage itself. I've configured
>>>>> multipathing correctly and added an alias for the wwid of the LUN so I
>>>>> can
>>>>> distinct this one and any other future volumes more easily. At first I
>>>>> created a partition on it but since oVirt saw only the whole LUN as raw
>>>>> device I erased it before adding it as the FC master storage domain. I've
>>>>> imported a few VM's and point them to the FC storage domain. This setup
>>>>> works, but:
>>>>>
>>>>> - All of the nodes see a device with the alias for the wwid of the
>>>>> volume,
>>>>> but only the node wich is currently the SPM for the cluster can see
>>>>> logical
>>>>> volumes inside. Also when I setup the high availability for VM's residing
>>>>> on the FC storage and select to start on any node on the cluster, they
>>>>> always start on the SPM. Can multiple nodes run different VM's on the
>>>>> same
>>>>> FC storage at the same time (logical thing would be that they can, but I
>>>>> wanted to be sure first). I am not familiar with the logic oVirt utilizes
>>>>> that locks the vm's logical volume to prevent corruption.
>>>>>
>>>>> - Fdisk shows that logical volumes on the LUN of the FC volume are
>>>>> missaligned (partition doesn't end on cylindar boundary), so I wonder if
>>>>> this is becuase I imported the VM's with disks that were created on local
>>>>> storage before and that any _new_ VM's with disks on the fc storage would
>>>>> be propperly aligned.
>>>>>
>>>>> This is a new setup with oVirt 3.4 (did an export of all the VM's on 3.3
>>>>> and after a fresh installation of the 3.4 imported them back again). I
>>>>> have room to experiment a little with 2 of the 4 nodes because currently
>>>>> they are free from running any VM's, but I have limited room for
>>>>> anything else that would cause an unplanned downtime for four virtual
>>>>> machines running on the other two nodes on the cluster (currently highly
>>>>> available and their drives are on the FC storage domain). All in all I
>>>>> have 12 VM's running and I'm asking on the list for advice and guidance
>>>>> before I make any changes.
>>>>>
>>>>> Just trying to find as much info regarding all of this as possible before
>>>>> acting upon.
>>>>>
>>>>> Thank you in advance,
>>>>>
>>>>> Ivan
>>>> _______________________________________________
>>>> Users mailing list
>>>> Users at ovirt.org
>>>> http://lists.ovirt.org/mailman/listinfo/users
>

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