Thanks for your clarification. I see now. You were referring to a networking
problem where one host could not see the storage (but the storage was still up
and running).
On 3/13/17, 10:31 PM, "Jeromy Grimmett" <jer...@cloudbrix.com> wrote:
I apologize for the delay on the response, let me clarify the points
requested:
Mike asked:
"What I was curious about is if you plan to exclusively build your feature
as a set of scripts and/or if you plan to update the CloudStack code base, as
well."
JG: My idea was to do this separately as a plugin, then add it to the code
base down the road.
"Also, if a primary storage actually goes offline, I'm not clear on how
starting an impacted VM on a different compute host would help. Could you
clarify this for me?"
JG: The VM would be started on another host that still has access to the
storage. Individually a host can have problems and lose its connectivity to a
primary storage device. The solution we are working on would help to get the
VM back and up running much faster than waiting for Cloudstack to make a
decision to restart the VM on a different host.
Paul asked:
" 1. We can't/don't run scripts on vSphere hosts (not sure about Hyper-V)"
JG: I should have been more clear, this is for KVM hosts.
"2. I know of one failure scenario (which happened) where MTU issues in
intermediate switches meant that small amounts of data could pass, but anything
that was passed as jumbo frames then failed. So it would be important to
exercise that."
JG: I have faced this Jumbo Frame issue as well, perhaps we need to have
an option that would indicate Jumbo Frames are being used to access that
storage and the test result would reflect a failure to access using Jumbo
Frames.
"3. You need to be very sure of failures before shutting hosts down. Also
a host is likely to be connected to multiple storage pools, so you wouldn't
want to shut down a host due to one pool becoming unavailable."
JG: The script wouldn’t shut down any hosts at all. Just force stop the
affected VMs on that specific host and then start them on a host that is not
having the issue with storage.
"4. Environments can have hundreds of storage pools, so watch out for
spamming the logs with updates."
JG: The polling/testing time increments are configurable, so I am hoping
that can help with that. The results are pretty small and should be relatively
negligible.
"5. The primary storage pools have a 'state' which should get updated and
used by the deployment planners"
JG: I have copied Alex on this email to make sure he sees this suggestion.
We will figure out how to incorporate that 'state' field.
"6. Secondary storage pools don't have a 'state' - but it would be great
if that were added in the DB and reflected in the UI."
JG: For now, I think this might be a feature request that maybe we should
submit through the normal Cloudstack request process. Otherwise, we can
definitely include that into our work when we start to add it into the code
base.
To take this a step further, we are also working on a KVM host load
balancer that will be used as a factor when moving the VMs. We have a number
of little projects we are working on.
Thank you all for reviewing the information. All suggestions are welcome.
Jeromy Grimmett
P: 603.766.3625
jer...@cloudbrix.com
www.cloudbrix.com
-----Original Message-----
From: Paul Angus [mailto:paul.an...@shapeblue.com]
Sent: Saturday, March 11, 2017 2:43 AM
To: dev@cloudstack.apache.org
Subject: RE: [Proposal] - StorageHA
Hi Jeromy,
I love the idea, I'm not really a developer, so those guys will look at
things a different way, but...
These would be by my initial comments:
1. We can't/don't run scripts on vSphere hosts (not sure about Hyper-V)
2. I know of one failure scenario (which happened) where MTU issues in
intermediate switches meant that small amounts of data could pass, but anything
that was passed as jumbo frames then failed. So it would be important to
exercise that.
3. You need to be very sure of failures before shutting hosts down.
Also a host is likely to be connected to multiple storage pools, so you
wouldn't want to shut down a host due to one pool becoming unavailable.
4. Environments can have hundreds of storage pools, so watch out for
spamming the logs with updates.
5. The primary storage pools have a 'state' which should get updated and
used by the deployment planners
6. Secondary storage pools don't have a 'state' - but it would be great
if that were added in the DB and reflected in the UI.
Kind regards,
Paul Angus
paul.an...@shapeblue.com
www.shapeblue.com
53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue
From: Jeromy Grimmett [mailto:jer...@cloudbrix.com]
Sent: 10 March 2017 15:28
To: dev@cloudstack.apache.org
Subject: [Proposal] - StorageHA
Hello,
I am new to the mailing list, and we are glad to be a part of the
CloudStack community. We are looking to develop plugins and modules that will
help grow and expand the adoption and use of CloudStack. So as part of my
introductory email, I'd like to introduce a little project we have been working
on; a StorageHA Monitor. The Monitor would allow CloudStack and the hosts to
test, communicate and resolve VM availability issues when storage (primary
and/or secondary) availability becomes apparent. This is a small write up
about how it would work:
Consists of two scripts/programs:
The host script runs on the host servers and checks to see if the primary
and secondary storage is available by doing a read/write test then reports to
the master script that runs on the Cloudstack server. The host script will test
a read and a write to the storage every 5 seconds (configurable), and if it
fails 3 times (configurable) then it will be recorded by the master script.
The master script will monitor the results of the host script. If the test
is good, nothing happens and the results are logged and so that we can track
the history of the test results. If the test reports back as failed, then it
will perform the following actions:
* Secondary Storage - It will simply generate and send an alert that
the failure has occurred.
* Primary Storage - The script will perform the following tasks:
* Generate and send an alert that the failure has occurred.
* Force the VMs on that host to shutdown.
* Determine which host to move the VMs to.
* Start the VMs on the healthy host.
We have already started working on some code, and the solution seems to be
testing well. Any thoughts/ideas/input are(is) welcome. Should there are a
solution out there already, then please forgive our ignorance, and point us in
the right direction. We look forward to further collaboration with you all.
Regards,
j
Jeromy Grimmett
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155 Fleet Street
Portsmouth, NH 03801
Direct: 603.766.3625
Office: 603.766.4908
Fax: 603.766.4729
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