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

[Andrew Lau]

Interesting, which files did you modify to lower the log levels?

On Tue, Jun 3, 2014 at 12:38 AM,  <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. 11.44.33 combuster 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
>> >
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