/etc/libvirt/libvirtd.conf and /etc/vdsm/logger.conf

, but unfortunately maybe I've jumped to conclusions, last weekend, that very same thin provisioned vm was running a simple export for 3hrs before I've killed the process. But I wondered:

1. The process that runs behind the export is qemu-img convert (from raw to raw), and running iotop shows that every three or four seconds it reads 10-13 MBps and then idles for a few seconds. Run the numbers on 100GB (why is he covering the entire 100 of 15GB used on thin volume I still don't get it) and you get precisely 3-4 hrs estimated time remaining. 2. When I run export with SPM on a node that doesn't have any vm's running, export finishes for aprox. 30min (iotop shows 40-70MBps read speed constantly) 3. Renicing I/O priority of the qemu-img process as well as the CPU priority gave no results, it was still runing slow beyond any explanation.

Debug logs showed nothing of interest, so I disabled anything above warning and it suddenly accelerated the export, so I've connected the wrong dots.

On 06/10/2014 11:18 AM, Andrew Lau wrote:
Interesting, which files did you modify to lower the log levels?

On Tue, Jun 3, 2014 at 12:38 AM,  <combus...@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,  <combus...@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.



On Sunday, 1. June 2014. 11.44.33 combus...@archlinux.us wrote:

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
NFS based NAS device. I want to setup export and ISO domain on the NAS
there are no issues or questions regarding those two. I wasn't aware of
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
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
Gluster based domain with blocks for each partition. I guess it can be
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
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
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
but only the node wich is currently the SPM for the cluster can see
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
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,

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