6:05 a.m.
Hi all,
In the last 2.5 days I was exploring if and how we can integrate collectd and Vdsm.
The final picture could look like:
1. collectd does all the monitoring and reporting currently Vdsm does
2. Engine consumes data from collectd
3. Vdsm consumes *notifications* from collectd - for few but important tasks like Drive
high water mark monitoring
Benefits (aka: why to bother?):
1. less code in Vdsm / long-awaited modularization of Vdsm
2. better integration with the system, reuse of well-known components
3. more flexibility in monitoring/reporting: collectd is special purpose existing
solution
4. faster, more scalable operation because all the monitoring can be done in C
At first glance, Collectd seems to have all the tools we need.
1. A plugin interface (https://collectd.org/wiki/index.php/Plugin_architecture and
https://collectd.org/wiki/index.php/Table_of_Plugins)
2. Support for notifications and thresholds
(https://collectd.org/wiki/index.php/Notifications_and_thresholds)
3. a libvirt plugin https://collectd.org/wiki/index.php/Plugin:virt
So, the picture is like
1. we start requiring collectd as dependency of Vdsm
2. we either configure it appropriately (collectd support config drop-ins:
/etc/collectd.d) or we document our requirements (or both)
3. collectd monitors the hosts and libvirt
4. Engine polls collectd
5. Vdsm listens from notifications
Should libvirt deliver us the event we need (see
https://bugzilla.redhat.com/show_bug.cgi?id=1181659),
we can just stop using collectd notifications, everything else works as previously.
Challenges:
1. Collectd does NOT consider the plugin API stable
(https://collectd.org/wiki/index.php/Plugin_architecture#The_interface.27s...)
so the plugins should be inclueded in the main tree, much like the modules of the linux
kernel
Worth mentioning that the plugin API itself has a good deal of rough edges.
we will need to maintain this plugin ourselves, *and* we need to maintain our thin API
layer, to make sure the plugin loads and works with recent versions of collectd.
2. the virt plugin is out of date, doesn't report some data we need: see
https://github.com/collectd/collectd/issues/1945
3. the notification message(s) are tailored for human consumption, those messages are not
easy
to parse for machines.
4. the threshold support in collectd seems to match values against constants; it
doesn't seem possible
to match a value against another one, as we need to do for high water monitoring
(capacity VS allocation).
How I'm addressing, or how I plan to address those challenges (aka action items):
1. I've been experimenting with out-of-tree plugins, and I managed develop, build,
install and run
one out-of-tree plugin: https://github.com/mojaves/vmon/tree/master/collectd
The development pace of collectd looks sustainable, so this doesn't look such a big
deal.
Furthermore, we can engage with upstream to merge our plugins, either as-is or to
extend existing ones.
2. Write another collectd plugin based on the Vdsm python code and/or my past accelerator
executable project
(https://github.com/mojaves/vmon)
3. patch the collectd notification code. It is yet another plugin
OR
4. send notification from the new virt module as per #2, bypassing the threshold system.
This move could preclude
the new virt module to be merged in the collectd tree.
Current status of the action items:
1. done BUT PoC quality
2. To be done (more work than #1/possible dupe with github issue)
3. need more investigation, conflicts with #4
4. need more investigation, conflicts with #3
All the code I'm working on will be found on https://github.com/mojaves/vmon
Comments are appreciated
--
Francesco Romani
RedHat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani
6:46 a.m.
On Tue, Oct 11, 2016 at 2:05 PM, Francesco Romani <fromani(a)redhat.com> wrote:
Hi all,
In the last 2.5 days I was exploring if and how we can integrate collectd and Vdsm.
Some comments regarding storage high watermarks only. I will comment later
on other aspects.
The final picture could look like:
1. collectd does all the monitoring and reporting currently Vdsm does
2. Engine consumes data from collectd
3. Vdsm consumes *notifications* from collectd - for few but important tasks like Drive
high water mark monitoring
Drive high watermark is our core business, we cannot outsource
it to collectd.
Vdsm will always monitor high watermarks directly from libvirt.
Benefits (aka: why to bother?):
1. less code in Vdsm / long-awaited modularization of Vdsm
2. better integration with the system, reuse of well-known components
3. more flexibility in monitoring/reporting: collectd is special purpose existing
solution
4. faster, more scalable operation because all the monitoring can be done in C
If the problem in monitoring is python, we can have small and simple
helper doing the monitoring (for storage), like ioprocess.
At first glance, Collectd seems to have all the tools we need.
1. A plugin interface (https://collectd.org/wiki/index.php/Plugin_architecture and
https://collectd.org/wiki/index.php/Table_of_Plugins)
2. Support for notifications and thresholds
(https://collectd.org/wiki/index.php/Notifications_and_thresholds)
Setting threshhold and getting notifications when treshold is reached
sounds like the best design for monitoring drive high watermarks.
But I would like to depend on component that does *only* this task, and
service only vdsm.
3. a libvirt plugin https://collectd.org/wiki/index.php/Plugin:virt
So, the picture is like
1. we start requiring collectd as dependency of Vdsm
2. we either configure it appropriately (collectd support config drop-ins:
/etc/collectd.d) or we document our requirements (or both)
3. collectd monitors the hosts and libvirt
4. Engine polls collectd
5. Vdsm listens from notifications
Sounds good
Should libvirt deliver us the event we need (see
https://bugzilla.redhat.com/show_bug.cgi?id=1181659),
we can just stop using collectd notifications, everything else works as previously.
Challenges:
1. Collectd does NOT consider the plugin API stable
(https://collectd.org/wiki/index.php/Plugin_architecture#The_interface.27s...)
so the plugins should be inclueded in the main tree, much like the modules of the
linux kernel
Worth mentioning that the plugin API itself has a good deal of rough edges.
we will need to maintain this plugin ourselves, *and* we need to maintain our thin
API
layer, to make sure the plugin loads and works with recent versions of collectd.
2. the virt plugin is out of date, doesn't report some data we need: see
https://github.com/collectd/collectd/issues/1945
3. the notification message(s) are tailored for human consumption, those messages are not
easy
to parse for machines.
4. the threshold support in collectd seems to match values against constants; it
doesn't seem possible
to match a value against another one, as we need to do for high water monitoring
(capacity VS allocation).
How I'm addressing, or how I plan to address those challenges (aka action items):
1. I've been experimenting with out-of-tree plugins, and I managed develop, build,
install and run
one out-of-tree plugin: https://github.com/mojaves/vmon/tree/master/collectd
The development pace of collectd looks sustainable, so this doesn't look such a
big deal.
Furthermore, we can engage with upstream to merge our plugins, either as-is or to
extend existing ones.
2. Write another collectd plugin based on the Vdsm python code and/or my past accelerator
executable project
(https://github.com/mojaves/vmon)
3. patch the collectd notification code. It is yet another plugin
OR
4. send notification from the new virt module as per #2, bypassing the threshold system.
This move could preclude
the new virt module to be merged in the collectd tree.
Current status of the action items:
1. done BUT PoC quality
2. To be done (more work than #1/possible dupe with github issue)
3. need more investigation, conflicts with #4
4. need more investigation, conflicts with #3
All the code I'm working on will be found on https://github.com/mojaves/vmon
Comments are appreciated
--
Francesco Romani
RedHat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani
3:31 p.m.
On Tue, Oct 11, 2016 at 2:05 PM, Francesco Romani <fromani(a)redhat.com>
wrote:
Hi all,
In the last 2.5 days I was exploring if and how we can integrate collectd
and Vdsm.
The final picture could look like:
1. collectd does all the monitoring and reporting currently Vdsm does
2. Engine consumes data from collectd
3. Vdsm consumes *notifications* from collectd - for few but important
tasks like Drive high water mark monitoring
Benefits (aka: why to bother?):
1. less code in Vdsm / long-awaited modularization of Vdsm
2. better integration with the system, reuse of well-known components
3. more flexibility in monitoring/reporting: collectd is special purpose
existing solution
4. faster, more scalable operation because all the monitoring can be done
in C
At first glance, Collectd seems to have all the tools we need.
1. A plugin interface (https://collectd.org/wiki/
index.php/Plugin_architecture and https://collectd.org/wiki/
index.php/Table_of_Plugins)
2. Support for notifications and thresholds (https://collectd.org/wiki/
index.php/Notifications_and_thresholds)
3. a libvirt plugin https://collectd.org/wiki/index.php/Plugin:virt
So, the picture is like
1. we start requiring collectd as dependency of Vdsm
2. we either configure it appropriately (collectd support config drop-ins:
/etc/collectd.d) or we document our requirements (or both)
3. collectd monitors the hosts and libvirt
4. Engine polls collectd
5. Vdsm listens from notifications
Should libvirt deliver us the event we need (see
https://bugzilla.redhat.com/show_bug.cgi?id=1181659),
we can just stop using collectd notifications, everything else works as
previously.
Challenges:
1. Collectd does NOT consider the plugin API stable (
https://collectd.org/wiki/index.php/Plugin_architecture#
The_interface.27s_stability)
so the plugins should be inclueded in the main tree, much like the
modules of the linux kernel
Worth mentioning that the plugin API itself has a good deal of rough
edges.
we will need to maintain this plugin ourselves, *and* we need to
maintain our thin API
layer, to make sure the plugin loads and works with recent versions of
collectd.
2. the virt plugin is out of date, doesn't report some data we need: see
https://github.com/collectd/collectd/issues/1945
3. the notification message(s) are tailored for human consumption, those
messages are not easy
to parse for machines.
4. the threshold support in collectd seems to match values against
constants; it doesn't seem possible
to match a value against another one, as we need to do for high water
monitoring (capacity VS allocation).
How I'm addressing, or how I plan to address those challenges (aka action
items):
1. I've been experimenting with out-of-tree plugins, and I managed
develop, build, install and run
one out-of-tree plugin: https://github.com/mojaves/
vmon/tree/master/collectd
The development pace of collectd looks sustainable, so this doesn't
look such a big deal.
Furthermore, we can engage with upstream to merge our plugins, either
as-is or to extend existing ones.
2. Write another collectd plugin based on the Vdsm python code and/or my
past accelerator executable project
(https://github.com/mojaves/vmon)
3. patch the collectd notification code. It is yet another plugin
OR
4. send notification from the new virt module as per #2, bypassing the
threshold system. This move could preclude
the new virt module to be merged in the collectd tree.
Current status of the action items:
1. done BUT PoC quality
2. To be done (more work than #1/possible dupe with github issue)
3. need more investigation, conflicts with #4
4. need more investigation, conflicts with #3
All the code I'm working on will be found on https://github.com/mojaves/
vmon
Comments are appreciated
This generally sounds like a good idea - and I hope it is coordinated with
our efforts for monitoring (see [1], [2]).
Note that ages ago, ovirt-node actually had it already[3].
Few notes:
- I think the most compelling reason to move to collectd is actually to
benefit from the already existing plugins that it already has, which will
cover
a lot of the missing monitoring requirements and wishes we have (example:
local disk usage on the host), as well as integrate it into
Engine monitoring (example: postgresql performance monitoring).
- You can't remove monitoring from VDSM - as it new VDSM may work against
older Engine setups. You can gradually remove them.
I'd actually begin with cleanup - there are some 'metrics' that are simply
not needed and should not be reported in the first place and
are there for historic reasons only. Remove them - from Engine first, from
the DB and all, then later we can either send fake values or remove
from VDSM.
- If you are moving to collectd, as you can see from the metrics effort,
we'd really want to send it elsewhere - and Engine should consume it from
there.
Metrics storages usually have a very nice REST UI with the ability to bring
series with average, with different criteria (such as per hour, per minute
or what not stats), etc.
- I agree with Nir about separating between our core business and the
monitoring we do for extra. Keep in mind that some of the stats are for SLA
and critical scheduling decisions as well.
- The libvirt collectd plugin is REALLY outdated. I think it may require
significant work to bring it up to speed with our existing capabilities.
Y.
[1] https://sradcoblog.wordpress.com/2016/07/19/ovirt-metrics-elk/
[2] https://bronhaim.wordpress.com/2016/06/26/ovirt-metrics/
[3] https://github.com/oVirt/ovirt-node/blob/master/scripts/collectd.conf.in
--
Francesco Romani
RedHat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani
_______________________________________________
Devel mailing list
Devel(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/devel
2:29 a.m.
----- Original Message -----
From: "Yaniv Kaul" <ykaul(a)redhat.com>
To: "Francesco Romani" <fromani(a)redhat.com>
Cc: "devel" <devel(a)ovirt.org>
Sent: Tuesday, October 11, 2016 10:31:14 PM
Subject: Re: [ovirt-devel] [vdsm] exploring a possible integration between collectd and
Vdsm
On Tue, Oct 11, 2016 at 2:05 PM, Francesco Romani <fromani(a)redhat.com>
wrote:
> Hi all,
>
> In the last 2.5 days I was exploring if and how we can integrate collectd
> and Vdsm.
[...]
This generally sounds like a good idea - and I hope it is coordinated
with
our efforts for monitoring (see [1], [2]).
Sure it will. I played a couple of days with collectd to "just" see
a. how hard is to write a collectd plugin, and/or if it is feasible to
ship ot out-of-tree for the initial few releases, until it stabilizes
so it can be submitted upstream
b. if we can get events/notifications from collectd
c. if we can integrate those notifications with Vdsm
And turns out we *can* do all of the above, with various degrees of difficulty.
Few notes:
- I think the most compelling reason to move to collectd is actually to
benefit from the already existing plugins that it already has, which will
cover
a lot of the missing monitoring requirements and wishes we have (example:
local disk usage on the host), as well as integrate it into
Engine monitoring (example: postgresql performance monitoring).
Agreed
- You can't remove monitoring from VDSM - as it new VDSM may work
against
older Engine setups. You can gradually remove them.
Yes, for example we can make Vdsm poll collectd and act as facade to old Engines,
while new one should skip this step and ask collectd or the metrics aggregator
service you mention below.
I'd actually begin with cleanup - there are some
'metrics' that are simply
not needed and should not be reported in the first place and
are there for historic reasons only. Remove them - from Engine first, from
the DB and all, then later we can either send fake values or remove
from VDSM.
Yes, this is the first place where we need to coordinate with the metrics effort.
- If you are moving to collectd, as you can see from the metrics
effort,
we'd really want to send it elsewhere - and Engine should consume it from
there.
Metrics storages usually have a very nice REST UI with the ability to bring
series with average, with different criteria (such as per hour, per minute
or what not stats), etc.
Fully agreed
- I agree with Nir about separating between our core business and
the
monitoring we do for extra. Keep in mind that some of the stats are for SLA
and critical scheduling decisions as well.
Yes, of course adding a dependency for core monitoring is risky.
So far the bottom line is that relying on collectd for this is just one more
option on the table now.
[mostly brainstorming from now on]
However, I'd like highlight that is not just risky: is a different tradeoff.
Doing the core monitoring in Vdsm (so in python, essentially in a single threaded server)
is not a free lunch, because this has a quite high price on performance level.
If the main Vdsm process is overloaded, then the polling cycle can get longer, and the
overall response time of processing system events (e.g. disk detected full) can get
longer as well.
We've observed in not-so-distant past high response time from heavily loaded Vdsm.
I think the idea of having different instances for different monitoring purposes
(credit to Nir) is the best shot at the moment.
We could maybe have one standard system collectd for regular monitoring,
and perhaps one special purpose, very limited collectd instance for critical information.
On top of that, Vdsm could double-checl and keep doing the core monitoring itself,
albeit at lower rate (e.g. every 10s instead of every 2s; every 60s instead of every
15s).
Leveraging libvirt events is *the* right thing, no doubt about that, but it would be very
nice
to have a dependable external service which can generate the events we need based on
libvirt data, and move the notification logic on top of it.
Something like (final picture, excluding intermediate compatibility layers)
[data source]
-----+-------
|
`-> [monitoring/metrics collection]
-------------+---------------
|
+--> [metrics store] -{data}-> [Engine]
|
`--> [notification service] -{events}-> [Vdsm]
Not all the "boxes" need to be separate processes, for example collectd has
some
support for thresholds and notifications which is ~80% of what Vdsm needs (again not
considering reliability, just feature-wise).
[end brainstorm]
- The libvirt collectd plugin is REALLY outdated. I think it may
require
significant work to bring it up to speed with our existing capabilities.
Yep I looked briefly at that code. It is REALLY outdated :)
Besides some information just not reported (easy to fix),
we will most likely need to have here some logic to deal with stuck VMs,
much like we do in Vdsm.
In the past I ported some Vdsm monitoring code to C[1], this could perhaps help now.
Bests,
+++
[1] https://github.com/mojaves/vmon/tree/master/src
--
Francesco Romani
Red Hat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani
2:34 a.m.
----- Original Message -----
From: "Francesco Romani" <fromani(a)redhat.com>
To: "devel" <devel(a)ovirt.org>
Sent: Wednesday, October 12, 2016 9:29:37 AM
Subject: Re: [ovirt-devel] [vdsm] exploring a possible integration between collectd and
Vdsm
----- Original Message -----
> From: "Yaniv Kaul" <ykaul(a)redhat.com>
> To: "Francesco Romani" <fromani(a)redhat.com>
> Cc: "devel" <devel(a)ovirt.org>
> Sent: Tuesday, October 11, 2016 10:31:14 PM
> Subject: Re: [ovirt-devel] [vdsm] exploring a possible integration between
> collectd and Vdsm
>
> On Tue, Oct 11, 2016 at 2:05 PM, Francesco Romani <fromani(a)redhat.com>
> wrote:
>
> > Hi all,
> >
> > In the last 2.5 days I was exploring if and how we can integrate collectd
> > and Vdsm.
[...]
> This generally sounds like a good idea - and I hope it is coordinated with
> our efforts for monitoring (see [1], [2]).
Sure it will.
Sure it will be coordinated with the monitoring efforts*.
--
Francesco Romani
Red Hat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani
2761
days inactive
2762
days old
4 comments
3 participants
participants (3)
-
Francesco Romani -
Nir Soffer -
Yaniv Kaul