libvirt users - May 2014 - Re: [libvirt] Host OS, Storage Info

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...?...

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

Suggestions?

Many thanks in advance,

Tom






On Thu, May 22, 2014 at 9:16 AM, Martin Kletzander <mkletzan@redhat.com>
wrote:
> On Thu, May 22, 2014 at 12:16:17PM +0530, Sijo Jose wrote:
>
>> Hi,
>> Is there any way to get host OS information and host Storage in
formations
>> using libvirt API...?
>> Rgds
>> -Sijo
>>
>
> Check virsh help (most of the commands you probably want start with
> 'node' or 'vol'/'pool') or have a look at our
hvsupport page [1] for
> virNode* and virStorage* functions.
>
> If this isn't what you're looking for, specify your question in a
> better way.
>
> Martin
>
> [1] http://libvirt.org/hvsupport.html
>
> _______________________________________________
> libvirt-users mailing list
> libvirt-users@redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users
>

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

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?

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
>