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Re: [libvirt-users] [libvirt] Host OS, Storage Info



On Fri, May 30, 2014 at 07:31:28AM -0400, Ainsworth, Thomas wrote:
Martin,

Thanks for the information.  That makes sense.  I *believe* we are good
there.

I noticed something weird yesterday.  After a clone (via the virt-manager
GUI) it seems libvirtd locked up.   A force quit pop up appeared - I had to
kill it.  Then I restarted libvirtd.  Then I did a "ps -edf | grep libvirt"
and there were three (3) libvirtd --daemon processes.  Then any virsh
commands or virt-manager GUI (when it finally would come up) was very
sluggish.  By the end of the day I had four (4) of the processes running.
Keep in mind, whilst all of this is going on the VM's were just cranking
along fine.  I could not find any dead PID files elated to the processes to
kill...

...we rebooted the server at the end of the day.  It should be fine until
the next time I attempt a clone operation - which I am hesitant to do for
obvious reasons...

Any ideas?


I'd definitely try looking at the debug logs to see what the daemon is
doing, when there are more processes I'd try looking what the others
are doing by attaching with strace/gdb/whatever.

As a way out you can always stop the daemon, (kill all remaining ones
in your case) and start the daemon again.

Martin

Thanks,

Tom




On Fri, May 30, 2014 at 5:12 AM, Martin Kletzander <mkletzan redhat com>
wrote:

On Thu, May 29, 2014 at 01:31:13PM -0400, Ainsworth, Thomas wrote:

Martin, et al,

Sorry for the lag in response.

So I started playing with the various virsh commands.  Awesome.
Been doing some reading and I believe I have some things configured not so
well.
As I stated earlier in the thread, we have all of the VM image files on
one
RAID5.  Very fast machine.

When using top, the load average is a stable "5.xx".  No I/O wait. GB's of
free memory.  Swap has not been touched.
Using vmstat, I am writing to the RAID5 volume at a constant 150MB/s and
reading at a constant 275MB/s.

With all of that said, here are some results from virsh commands:

# virsh pool-list --all
Name                 State      Autostart
------------------------------------------------------
default              active     yes


# virsh pool-info default
Name:           default
UUID:            xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
State:          running
Persistent:     yes
Autostart:      yes
Capacity:       30.76 GiB
Allocation:     2.10 GiB
Available:      28.66 GiB


Now, is that ok to have all of the VM's using a default pool?
Or should a pool be created for each VM instance.
I honestly am not even sure what a pool references...?...


Pool is a set of volumes of the same type (iscsi, LVs, files in a
folder, etc.) in the same place.  Example is the default pool which is,
by default, in /var/lib/libvirt/images and volumes there are files
(pool type is "dir").  If you want to have all the domain disks in
that place and all the disks (volumes) should be files then default
pool is enough.


 The more I read, the more I am moving away from thinking something in the
OS is the cause of my sluggishness.


I haven't read your previous mail before, so I've found that now.  How
often are you dropping those caches?  That won't help you not to use
swap.  Having memory occupied by buffers and caches is good if you
read/write from/to disks.  Even when the reads/writes are as fast as
you mentioned, reading/writing from/to RAM is way faster and until
there's some free memory, why not use that?

Martin


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