Re: [ClusterLabs] Two-node cluster fencing

2018-05-14 Thread Ken Gaillot 
On Sat, 2018-05-12 at 12:51 -0600, Casey & Gina Shobe wrote:
> Without fencing, if the primary is powered off abruptly (e.g. if one
> of your ESX servers crashes), the standby will not become primary,
> and you will need to promote it manually.  We had exactly this
> scenario happen last week with a 2-node cluster.  Without fencing,
> you don't have high availability.  If you don't need high
> availability, you probably don't need pacemaker.

To go into this a bit more, the reason it's not safe to operate without
fencing is the situation where the active node still has the IP, but
has stopped responding for whatever reason (crippling load, failed
disk, flaky network card, etc.). If the passive node brought up the IP
in this case without first fencing the active node, both VMs would
advertise the IP, and packets would (practically speaking) randomly go
to one or the other, making any sort of communication impossible.

> There are instructions for setting up fencing with vmware here:  http
> s://www.hastexo.com/resources/hints-and-kinks/fencing-vmware-
> virtualized-pacemaker-nodes/
> 
> One note - rather than the SDK, I believe you actually need the CLI
> package, which can be found here:  https://my.vmware.com/web/vmware/d
> etails?downloadGroup=VCLI600=491
> 
> Good luck - I haven't managed to get it to build yet - vmware gives
> you a black box installer script that compiles a bunch of dependent
> perl modules, and it ends up getting hung with 100% CPU usage for
> days - digging into this further with lsof and friends, it seems to
> be prompting for where your apache source code is to compile
> mod_perl.  Why does it need mod_perl for the CLI??  Anyways, I
> haven't managed to get past that roadblock yet.  I'm using Ubuntu 16
> so it may happen to just work better on your RHEL instances.  If you
> have a different ESX version than 6.0, you may have better luck as
> well.
> 
> Best wishes,
-- 
Ken Gaillot 
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[ClusterLabs] Two-node cluster fencing

2018-05-13 Thread Confidential Company 
Message: 2
Date: Sun, 13 May 2018 10:20:36 +0300
From: Andrei Borzenkov <arvidj...@gmail.com>
To: users@clusterlabs.org
Subject: Re: [ClusterLabs] Two-node cluster fencing
Message-ID: <f61a61bc-f618-bdb1-ee1a-bc5e856c8...@gmail.com>
Content-Type: text/plain; charset=utf-8

12.05.2018 07:31, Confidential Company ?:
> Hi,
>
> This is my setup:
>
> 1. I have Two vMware-ESXI hosts with one virtual machine (RHEL 7.4) on
each.
> 2. On my physical machine, I have four vmnic --> vmnic 0,1 for uplink
going
> to switchA and switchB --> vmnic 2,3 for heartbeat corosync traffic
(direct
> connect to other ESXI host)
> 3. I plan on clustering my two virtual machines via corosync and create a
> virtual-IP via pacemaker.
> 4. I plan on using the uplink interface for data and totem interface for
> corosync packets(heartbeat messages).
> 5. These two virtual machines doesnt need for a shared storage, or a
shared
> LUN because the application is, by nature, a standalone application that
> doesnt need to have a centralized location as it does not store any data
> that needs to be synchronized between two servers.

>Then why you need fialover cluster in the first place? Why cannot you
have both nodes running at the same time and use virtual server to let
clients connect to either of them?


*Reply to Andrei: *I want to it to be simple as possible. If I setup them
as active/active, i need a loadbalancer (nginx I assume). Or maybe you have
suggestions. Thanks bro




> 6. I have a PC that only needs to contact the Virtual IP of the rhel
> virtual servers.
> 7. Seamless failover from primary to secondary is not required.> 8.
Active/Passive setup
>
>
> Given the setup above,
> 1. Is there any drawbacks?
> 2. Do I need fencing? Can you explain me by giving a scenario on the above
> setup? What instances will occur if I didnt put a fence device?
> 3. If I need a fence device? what fence device you recommend? SAN, vmWare,
> or PDU?
>
>
> Thanks,
>
> imnotarobot
>
>
>
> ___
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Re: [ClusterLabs] Two-node cluster fencing

2018-05-13 Thread Andrei Borzenkov 
12.05.2018 07:31, Confidential Company пишет:
> Hi,
> 
> This is my setup:
> 
> 1. I have Two vMware-ESXI hosts with one virtual machine (RHEL 7.4) on each.
> 2. On my physical machine, I have four vmnic --> vmnic 0,1 for uplink going
> to switchA and switchB --> vmnic 2,3 for heartbeat corosync traffic (direct
> connect to other ESXI host)
> 3. I plan on clustering my two virtual machines via corosync and create a
> virtual-IP via pacemaker.
> 4. I plan on using the uplink interface for data and totem interface for
> corosync packets(heartbeat messages).
> 5. These two virtual machines doesnt need for a shared storage, or a shared
> LUN because the application is, by nature, a standalone application that
> doesnt need to have a centralized location as it does not store any data
> that needs to be synchronized between two servers.

Then why you need fialover cluster in the first place? Why cannot you
have both nodes running at the same time and use virtual server to let
clients connect to either of them?

> 6. I have a PC that only needs to contact the Virtual IP of the rhel
> virtual servers.
> 7. Seamless failover from primary to secondary is not required.> 8. 
> Active/Passive setup
> 
> 
> Given the setup above,
> 1. Is there any drawbacks?
> 2. Do I need fencing? Can you explain me by giving a scenario on the above
> setup? What instances will occur if I didnt put a fence device?
> 3. If I need a fence device? what fence device you recommend? SAN, vmWare,
> or PDU?
> 
> 
> Thanks,
> 
> imnotarobot
> 
> 
> 
> ___
> Users mailing list: Users@clusterlabs.org
> https://lists.clusterlabs.org/mailman/listinfo/users
> 
> Project Home: http://www.clusterlabs.org
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> Bugs: http://bugs.clusterlabs.org
> 

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Re: [ClusterLabs] Two-node cluster fencing

2018-05-12 Thread Casey & Gina Shobe 
Without fencing, if the primary is powered off abruptly (e.g. if one of your 
ESX servers crashes), the standby will not become primary, and you will need to 
promote it manually.  We had exactly this scenario happen last week with a 
2-node cluster.  Without fencing, you don't have high availability.  If you 
don't need high availability, you probably don't need pacemaker.

There are instructions for setting up fencing with vmware here:  
https://www.hastexo.com/resources/hints-and-kinks/fencing-vmware-virtualized-pacemaker-nodes/

One note - rather than the SDK, I believe you actually need the CLI package, 
which can be found here:  
https://my.vmware.com/web/vmware/details?downloadGroup=VCLI600=491

Good luck - I haven't managed to get it to build yet - vmware gives you a black 
box installer script that compiles a bunch of dependent perl modules, and it 
ends up getting hung with 100% CPU usage for days - digging into this further 
with lsof and friends, it seems to be prompting for where your apache source 
code is to compile mod_perl.  Why does it need mod_perl for the CLI??  Anyways, 
I haven't managed to get past that roadblock yet.  I'm using Ubuntu 16 so it 
may happen to just work better on your RHEL instances.  If you have a different 
ESX version than 6.0, you may have better luck as well.

Best wishes,
-- 
Casey

> On May 11, 2018, at 10:31 PM, Confidential Company  
> wrote:
> 
> Hi,
> 
> This is my setup:
> 
> 1. I have Two vMware-ESXI hosts with one virtual machine (RHEL 7.4) on each.
> 2. On my physical machine, I have four vmnic --> vmnic 0,1 for uplink going 
> to switchA and switchB --> vmnic 2,3 for heartbeat corosync traffic (direct 
> connect to other ESXI host)
> 3. I plan on clustering my two virtual machines via corosync and create a 
> virtual-IP via pacemaker. 
> 4. I plan on using the uplink interface for data and totem interface for 
> corosync packets(heartbeat messages).
> 5. These two virtual machines doesnt need for a shared storage, or a shared 
> LUN because the application is, by nature, a standalone application that 
> doesnt need to have a centralized location as it does not store any data that 
> needs to be synchronized between two servers.
> 6. I have a PC that only needs to contact the Virtual IP of the rhel virtual 
> servers.
> 7. Seamless failover from primary to secondary is not required. 
> 8. Active/Passive setup
> 
> 
> Given the setup above, 
> 1. Is there any drawbacks?
> 2. Do I need fencing? Can you explain me by giving a scenario on the above 
> setup? What instances will occur if I didnt put a fence device?
> 3. If I need a fence device? what fence device you recommend? SAN, vmWare, or 
> PDU?
> 
> 
> Thanks,
> 
> imnotarobot
> 
> ___
> Users mailing list: Users@clusterlabs.org
> https://lists.clusterlabs.org/mailman/listinfo/users
> 
> Project Home: http://www.clusterlabs.org
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> Bugs: http://bugs.clusterlabs.org

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[ClusterLabs] Two-node cluster fencing

2018-05-11 Thread Confidential Company 
Hi,

This is my setup:

1. I have Two vMware-ESXI hosts with one virtual machine (RHEL 7.4) on each.
2. On my physical machine, I have four vmnic --> vmnic 0,1 for uplink going
to switchA and switchB --> vmnic 2,3 for heartbeat corosync traffic (direct
connect to other ESXI host)
3. I plan on clustering my two virtual machines via corosync and create a
virtual-IP via pacemaker.
4. I plan on using the uplink interface for data and totem interface for
corosync packets(heartbeat messages).
5. These two virtual machines doesnt need for a shared storage, or a shared
LUN because the application is, by nature, a standalone application that
doesnt need to have a centralized location as it does not store any data
that needs to be synchronized between two servers.
6. I have a PC that only needs to contact the Virtual IP of the rhel
virtual servers.
7. Seamless failover from primary to secondary is not required.
8. Active/Passive setup


Given the setup above,
1. Is there any drawbacks?
2. Do I need fencing? Can you explain me by giving a scenario on the above
setup? What instances will occur if I didnt put a fence device?
3. If I need a fence device? what fence device you recommend? SAN, vmWare,
or PDU?


Thanks,

imnotarobot
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