Re: [devel] Review Request for doc: update overview PR for split brain prevention with consensus service [#64]

2018-02-15 Thread Ravi Sekhar Reddy Konda 

Thanks Gary,

Also I asked for the sample configuration of raft cluster when raft servers are 
part of OpenSAF cluster 

A Raft(etcd) cluster should use different interface other then what OpenSAF is 
using, so it will better to document this.
In general it will be good to have sample configuration about how to farm a 
raft cluster in the README as well as PR doc. 

Thanks,
Ravi
 


- Original Message -
From: gary@dektech.com.au
To: anders.wid...@ericsson.com, ravisekhar.ko...@oracle.com, 
hans.nordeb...@ericsson.com
Cc: opensaf-devel@lists.sourceforge.net
Sent: Monday, February 12, 2018 2:48:15 PM GMT +05:30 Chennai, Kolkata, Mumbai, 
New Delhi
Subject: Re: Review Request for doc: update overview PR for split brain 
prevention with consensus service [#64]

Hi Ravi/Anders

AndersW> This is slightly out of scope since there are many RAFT 
implementations, but I agree it could be a good idea to provide a sample 
configuration for etcd along with the sample etcd plugin.

 I will try to provide a sample plugin for an external etcd server, and maybe a 
sample plugin for another RAFT based key-value store.

Thanks
Gary



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Re: [devel] Review Request for doc: update overview PR for split brain prevention with consensus service [#64]

2018-02-15 Thread Ravi Sekhar Reddy Konda 
Hi Anders,

In case where Raft Cluster is outside the OpenSAF Cluster 
Then how can the quorum concept applies to OpenSAF cluster, because raft 
servers are outside the OpenSAF Cluster
they wont be able to determine which OpenSAF partition has more no of nodes 

Thanks,
Ravi

- Original Message -
From: anders.wid...@ericsson.com
To: ravisekhar.ko...@oracle.com, gary@dektech.com.au, 
hans.nordeb...@ericsson.com
Cc: opensaf-devel@lists.sourceforge.net
Sent: Thursday, February 8, 2018 3:21:15 PM GMT +05:30 Chennai, Kolkata, 
Mumbai, New Delhi
Subject: Re: Review Request for doc: update overview PR for split brain 
prevention with consensus service [#64]

See my comments inline, marked AndersW>

regards,

Anders Widell


On 02/08/2018 10:36 AM, Ravi Sekhar Reddy Konda wrote:
> Hi Gary,
>
> Have query regarding quorum selection when raft servers are external to the 
> OpenSAF Cluster
>
> In the document we are saying  "The consensus service uses quorum to prevent 
> state changes in network partitions that don't include more than half of the 
> nodes in the cluster"
>
> => This is possible if the raft server is installed on the OpenSAF Cluster 
> Nodes, as Raft decides which partition has more no of nodes.
> but in the case where raft servers run on external nodes outside of the 
> OpenSAF Cluster, how the quorum is decided

AndersW> If the consensus service is running on external servers then 
you need to have an appropriate number of them (probably three or five). 
Quorum is determined as the majority of these external servers, and is 
not in any way related to majority of the OpenSAF nodes. The consensus 
service will prevent split-brain within the OpenSAF cluster, but in case 
of a network partition it will not guarantee that the active system 
controller will be located in the largest partition. This situation is 
actually similar to the situation when you use TIPC for internal OpenSAF 
communication. You can have a split-brain in the TIPC network (for 
example due to misconfiguration or a bug in TIPC), but at the same time 
have full connectivity on the IP network which is used by RAFT. I think 
there were some review comments about this for ticket [#64] and I will 
write a follow-up ticket where we can address the possibility of moving 
the active system controller to a node in the largest network partition.

>
>
> => If the Raft Servers are external to OpenSAF Cluster, do we need to make 
> any configuration so that etcd client on the OpenSAF nodes
> communicates with Raft Leader
> Also it will be good if we give some details about how to install and 
> configure raft(raft servers within and external to the opensaf cluster)

AndersW> This is slightly out of scope since there are many RAFT 
implementations, but I agree it could be a good idea to provide a sample 
configuration for etcd along with the sample etcd plugin.

>
> Thanks,
> Ravi
>
> -Original Message-
> From: Gary Lee [mailto:gary@dektech.com.au]
> Sent: Friday, January 26, 2018 11:28 AM
> To: Hans Nordebäck ; Anders Widell 
> ; Ravi Sekhar Reddy Konda 
> 
> Cc: opensaf-devel@lists.sourceforge.net
> Subject: Review Request for doc: update overview PR for split brain 
> prevention with consensus service [#64]
>
> Hi
>
> I have updated the OpenSAF Overview PR document for ticket #64.
>
> Please have a look.
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__sourceforge.net_p_opensaf_tickets_-5Fdiscuss_thread_0d47d4b9_5489_attachment_OpenSAF-5FOverview-5FPR.odt=DwICaQ=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE=xBh_3WtlS1YjXd3Bui_nVjh5qwhU2UamdAhSfqynLU4=xCEIb5x0gLGfoZW5uOWz23MZa6HzmOa6Vhywz3WeIQs=RF6RsX3xhby4k4PnwA8WEXCWKg0JbFyGNgaiery9iDk=
>
> Thanks
> Gary
>



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Re: [devel] Review Request for doc: update overview PR for split brain prevention with consensus service [#64]

2018-02-12 Thread Gary Lee 
Hi Ravi/Anders

AndersW> This is slightly out of scope since there are many RAFT 
implementations, but I agree it could be a good idea to provide a sample 
configuration for etcd along with the sample etcd plugin.

 I will try to provide a sample plugin for an external etcd server, and maybe a 
sample plugin for another RAFT based key-value store.

Thanks
Gary



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Re: [devel] Review Request for doc: update overview PR for split brain prevention with consensus service [#64]

2018-02-08 Thread Anders Widell 

See my comments inline, marked AndersW>

regards,

Anders Widell


On 02/08/2018 10:36 AM, Ravi Sekhar Reddy Konda wrote:

Hi Gary,

Have query regarding quorum selection when raft servers are external to the 
OpenSAF Cluster

In the document we are saying  "The consensus service uses quorum to prevent state 
changes in network partitions that don't include more than half of the nodes in the 
cluster"

=> This is possible if the raft server is installed on the OpenSAF Cluster 
Nodes, as Raft decides which partition has more no of nodes.
but in the case where raft servers run on external nodes outside of the OpenSAF 
Cluster, how the quorum is decided


AndersW> If the consensus service is running on external servers then 
you need to have an appropriate number of them (probably three or five). 
Quorum is determined as the majority of these external servers, and is 
not in any way related to majority of the OpenSAF nodes. The consensus 
service will prevent split-brain within the OpenSAF cluster, but in case 
of a network partition it will not guarantee that the active system 
controller will be located in the largest partition. This situation is 
actually similar to the situation when you use TIPC for internal OpenSAF 
communication. You can have a split-brain in the TIPC network (for 
example due to misconfiguration or a bug in TIPC), but at the same time 
have full connectivity on the IP network which is used by RAFT. I think 
there were some review comments about this for ticket [#64] and I will 
write a follow-up ticket where we can address the possibility of moving 
the active system controller to a node in the largest network partition.





=> If the Raft Servers are external to OpenSAF Cluster, do we need to make any 
configuration so that etcd client on the OpenSAF nodes
communicates with Raft Leader
Also it will be good if we give some details about how to install and configure 
raft(raft servers within and external to the opensaf cluster)


AndersW> This is slightly out of scope since there are many RAFT 
implementations, but I agree it could be a good idea to provide a sample 
configuration for etcd along with the sample etcd plugin.




Thanks,
Ravi

-Original Message-
From: Gary Lee [mailto:gary@dektech.com.au]
Sent: Friday, January 26, 2018 11:28 AM
To: Hans Nordebäck ; Anders Widell 
; Ravi Sekhar Reddy Konda 
Cc: opensaf-devel@lists.sourceforge.net
Subject: Review Request for doc: update overview PR for split brain prevention 
with consensus service [#64]

Hi

I have updated the OpenSAF Overview PR document for ticket #64.

Please have a look.

https://urldefense.proofpoint.com/v2/url?u=https-3A__sourceforge.net_p_opensaf_tickets_-5Fdiscuss_thread_0d47d4b9_5489_attachment_OpenSAF-5FOverview-5FPR.odt=DwICaQ=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE=xBh_3WtlS1YjXd3Bui_nVjh5qwhU2UamdAhSfqynLU4=xCEIb5x0gLGfoZW5uOWz23MZa6HzmOa6Vhywz3WeIQs=RF6RsX3xhby4k4PnwA8WEXCWKg0JbFyGNgaiery9iDk=

Thanks
Gary





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Re: [devel] Review Request for doc: update overview PR for split brain prevention with consensus service [#64]

2018-02-08 Thread Ravi Sekhar Reddy Konda 
Hi Gary,

Have query regarding quorum selection when raft servers are external to the 
OpenSAF Cluster

In the document we are saying  "The consensus service uses quorum to prevent 
state changes in network partitions that don't include more than half of the 
nodes in the cluster"

=> This is possible if the raft server is installed on the OpenSAF Cluster 
Nodes, as Raft decides which partition has more no of nodes.
but in the case where raft servers run on external nodes outside of the OpenSAF 
Cluster, how the quorum is decided


=> If the Raft Servers are external to OpenSAF Cluster, do we need to make any 
configuration so that etcd client on the OpenSAF nodes
communicates with Raft Leader
Also it will be good if we give some details about how to install and configure 
raft(raft servers within and external to the opensaf cluster)

Thanks,
Ravi

-Original Message-
From: Gary Lee [mailto:gary@dektech.com.au] 
Sent: Friday, January 26, 2018 11:28 AM
To: Hans Nordebäck ; Anders Widell 
; Ravi Sekhar Reddy Konda 

Cc: opensaf-devel@lists.sourceforge.net
Subject: Review Request for doc: update overview PR for split brain prevention 
with consensus service [#64]

Hi

I have updated the OpenSAF Overview PR document for ticket #64.

Please have a look.

https://urldefense.proofpoint.com/v2/url?u=https-3A__sourceforge.net_p_opensaf_tickets_-5Fdiscuss_thread_0d47d4b9_5489_attachment_OpenSAF-5FOverview-5FPR.odt=DwICaQ=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE=xBh_3WtlS1YjXd3Bui_nVjh5qwhU2UamdAhSfqynLU4=xCEIb5x0gLGfoZW5uOWz23MZa6HzmOa6Vhywz3WeIQs=RF6RsX3xhby4k4PnwA8WEXCWKg0JbFyGNgaiery9iDk=

Thanks
Gary


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Re: [devel] Review Request for doc: update overview PR for split brain prevention with consensus service [#64]

2018-01-30 Thread Anders Widell 

Ack.

regards,

Anders Widell


On 01/26/2018 06:57 AM, Gary Lee wrote:

Hi

I have updated the OpenSAF Overview PR document for ticket #64.

Please have a look.

https://sourceforge.net/p/opensaf/tickets/_discuss/thread/0d47d4b9/5489/attachment/OpenSAF_Overview_PR.odt 



Thanks
Gary




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[devel] Review Request for doc: update overview PR for split brain prevention with consensus service [#64]

2018-01-25 Thread Gary Lee 

Hi

I have updated the OpenSAF Overview PR document for ticket #64.

Please have a look.

https://sourceforge.net/p/opensaf/tickets/_discuss/thread/0d47d4b9/5489/attachment/OpenSAF_Overview_PR.odt

Thanks
Gary


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