Re: [ceph-users] Monitor question

[Fran Barrera]

Ok, I understand, so I'll create a new mon to permit me stop the mon.a.

Thanks,
Fran.

2016-07-07 17:46 GMT+02:00 Joao Eduardo Luis :

> On 07/07/2016 04:39 PM, Fran Barrera wrote:
>
>> Yes, this is the problem.
>>
>
> Well, you lose quorum once you stop A.
>
> As the docs clearly state, you cannot tolerate failures if you have just
> two monitors.
>
> If your cluster only has two monitors, you cannot form quorum with just
> one monitor: you need a majority up, running and able to communicate among
> themselves.
>
> Simply put, you need at least (n+1)/2 monitors up for a quorum to be
> formed, 'n' being the total number of monitors in the cluster (i.e., in the
> monmap).
>
> You either need A and B to be running to be able to use the quorum, or you
> need to add another monitor (call it C) so that you can stop A and still
> have the cluster working.
>
>   -Joao
>
>
>> 2016-07-07 17:34 GMT+02:00 Joao Eduardo Luis > >:
>>
>> On 07/07/2016 04:31 PM, Fran Barrera wrote:
>>
>> Hello,
>>
>> Yes I've added two monitors but the error persist. In the error
>> I see
>> only the IP of the first mon, why not appears the second?
>>
>>
>> The description you offered on the initial email appears to state
>> the following:
>>
>> - You initially had one monitor (let's call it A)
>> - You added a second monitor (let's call it B)
>> - Everything works while A and B are running
>> - Nothing works if you stop A
>>
>> Did I understand your problem correctly?
>>
>>-Joao
>>
>>
>> I had only one monitors before and running good because I have
>> installed
>> AIO.
>>
>> Thanks.
>>
>> 2016-07-07 17:22 GMT+02:00 Joao Eduardo Luis > 
>> >>:
>>
>>
>>
>>  On 07/07/2016 04:17 PM, Fran Barrera wrote:
>>
>>  Hi all,
>>
>>  I have a cluster setup AIO with only one monitor and
>> now I've
>>  created
>>  another monitor in other server following this doc
>> http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/
>> but
>>  my
>>  problem is if I stop the AIO monitor, the cluster stop
>> working.
>>  It seems
>>  like the ceph is not updated with the new mon or
>> something
>>
>>
>>  In the doc you quoted, one can read:
>>
>>  "Due to the nature of Paxos, Ceph requires a majority of
>> monitors
>>  running to establish a quorum (thus establishing consensus).
>>
>>  [...]
>>
>>  For instance, on a 2 monitor deployment, no failures can be
>>  tolerated in order to maintain a quorum; with 3 monitors, one
>>  failure can be tolerated; [...]"
>>
>>  And in a box beneath, you also see
>>
>>  "Note:  A majority of monitors in your cluster must be able
>> to reach
>>  each other in order to establish a quorum."
>>
>>
>>  So, say you have 2 monitors and you need a majority of them
>> to be
>>  up, running, and able to communicate with each other in
>> order to
>>  form quorum. What's a majority of 2? How many failures can
>> you tolerate?
>>
>> -Joao
>>
>>
>>
>>
>>  ___
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>> > >
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>>
>>
>>
>>
>>
>
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Re: [ceph-users] Monitor question

[Joao Eduardo Luis]

On 07/07/2016 04:39 PM, Fran Barrera wrote:

Yes, this is the problem.


Well, you lose quorum once you stop A.

As the docs clearly state, you cannot tolerate failures if you have just 
two monitors.


If your cluster only has two monitors, you cannot form quorum with just 
one monitor: you need a majority up, running and able to communicate 
among themselves.


Simply put, you need at least (n+1)/2 monitors up for a quorum to be 
formed, 'n' being the total number of monitors in the cluster (i.e., in 
the monmap).


You either need A and B to be running to be able to use the quorum, or 
you need to add another monitor (call it C) so that you can stop A and 
still have the cluster working.


  -Joao



2016-07-07 17:34 GMT+02:00 Joao Eduardo Luis >:

On 07/07/2016 04:31 PM, Fran Barrera wrote:

Hello,

Yes I've added two monitors but the error persist. In the error
I see
only the IP of the first mon, why not appears the second?


The description you offered on the initial email appears to state
the following:

- You initially had one monitor (let's call it A)
- You added a second monitor (let's call it B)
- Everything works while A and B are running
- Nothing works if you stop A

Did I understand your problem correctly?

   -Joao


I had only one monitors before and running good because I have
installed
AIO.

Thanks.

2016-07-07 17:22 GMT+02:00 Joao Eduardo Luis 
>>:


 On 07/07/2016 04:17 PM, Fran Barrera wrote:

 Hi all,

 I have a cluster setup AIO with only one monitor and
now I've
 created
 another monitor in other server following this doc
http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/ but
 my
 problem is if I stop the AIO monitor, the cluster stop
working.
 It seems
 like the ceph is not updated with the new mon or something


 In the doc you quoted, one can read:

 "Due to the nature of Paxos, Ceph requires a majority of
monitors
 running to establish a quorum (thus establishing consensus).

 [...]

 For instance, on a 2 monitor deployment, no failures can be
 tolerated in order to maintain a quorum; with 3 monitors, one
 failure can be tolerated; [...]"

 And in a box beneath, you also see

 "Note:  A majority of monitors in your cluster must be able
to reach
 each other in order to establish a quorum."


 So, say you have 2 monitors and you need a majority of them
to be
 up, running, and able to communicate with each other in
order to
 form quorum. What's a majority of 2? How many failures can
you tolerate?

-Joao




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 ceph-users mailing list
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>
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Re: [ceph-users] Monitor question

[Fran Barrera]

Yes, this is the problem.

2016-07-07 17:34 GMT+02:00 Joao Eduardo Luis :

> On 07/07/2016 04:31 PM, Fran Barrera wrote:
>
>> Hello,
>>
>> Yes I've added two monitors but the error persist. In the error I see
>> only the IP of the first mon, why not appears the second?
>>
>
> The description you offered on the initial email appears to state the
> following:
>
> - You initially had one monitor (let's call it A)
> - You added a second monitor (let's call it B)
> - Everything works while A and B are running
> - Nothing works if you stop A
>
> Did I understand your problem correctly?
>
>   -Joao
>
>
>> I had only one monitors before and running good because I have installed
>> AIO.
>>
>> Thanks.
>>
>> 2016-07-07 17:22 GMT+02:00 Joao Eduardo Luis > >:
>>
>>
>> On 07/07/2016 04:17 PM, Fran Barrera wrote:
>>
>> Hi all,
>>
>> I have a cluster setup AIO with only one monitor and now I've
>> created
>> another monitor in other server following this doc
>> http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/
>> but
>> my
>> problem is if I stop the AIO monitor, the cluster stop working.
>> It seems
>> like the ceph is not updated with the new mon or something
>>
>>
>> In the doc you quoted, one can read:
>>
>> "Due to the nature of Paxos, Ceph requires a majority of monitors
>> running to establish a quorum (thus establishing consensus).
>>
>> [...]
>>
>> For instance, on a 2 monitor deployment, no failures can be
>> tolerated in order to maintain a quorum; with 3 monitors, one
>> failure can be tolerated; [...]"
>>
>> And in a box beneath, you also see
>>
>> "Note:  A majority of monitors in your cluster must be able to reach
>> each other in order to establish a quorum."
>>
>>
>> So, say you have 2 monitors and you need a majority of them to be
>> up, running, and able to communicate with each other in order to
>> form quorum. What's a majority of 2? How many failures can you
>> tolerate?
>>
>>-Joao
>>
>>
>>
>>
>> ___
>> ceph-users mailing list
>> ceph-users@lists.ceph.com 
>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>>
>>
>
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Re: [ceph-users] Monitor question

[Joao Eduardo Luis]

On 07/07/2016 04:31 PM, Fran Barrera wrote:

Hello,

Yes I've added two monitors but the error persist. In the error I see
only the IP of the first mon, why not appears the second?


The description you offered on the initial email appears to state the 
following:


- You initially had one monitor (let's call it A)
- You added a second monitor (let's call it B)
- Everything works while A and B are running
- Nothing works if you stop A

Did I understand your problem correctly?

  -Joao



I had only one monitors before and running good because I have installed
AIO.

Thanks.

2016-07-07 17:22 GMT+02:00 Joao Eduardo Luis >:

On 07/07/2016 04:17 PM, Fran Barrera wrote:

Hi all,

I have a cluster setup AIO with only one monitor and now I've
created
another monitor in other server following this doc
http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/ but
my
problem is if I stop the AIO monitor, the cluster stop working.
It seems
like the ceph is not updated with the new mon or something


In the doc you quoted, one can read:

"Due to the nature of Paxos, Ceph requires a majority of monitors
running to establish a quorum (thus establishing consensus).

[...]

For instance, on a 2 monitor deployment, no failures can be
tolerated in order to maintain a quorum; with 3 monitors, one
failure can be tolerated; [...]"

And in a box beneath, you also see

"Note:  A majority of monitors in your cluster must be able to reach
each other in order to establish a quorum."


So, say you have 2 monitors and you need a majority of them to be
up, running, and able to communicate with each other in order to
form quorum. What's a majority of 2? How many failures can you tolerate?

   -Joao




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Re: [ceph-users] Monitor question

[Fran Barrera]

Hello,

Yes I've added two monitors but the error persist. In the error I see only
the IP of the first mon, why not appears the second?

I had only one monitors before and running good because I have installed
AIO.

Thanks.

2016-07-07 17:22 GMT+02:00 Joao Eduardo Luis :

> On 07/07/2016 04:17 PM, Fran Barrera wrote:
>
>> Hi all,
>>
>> I have a cluster setup AIO with only one monitor and now I've created
>> another monitor in other server following this doc
>> http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/ but my
>> problem is if I stop the AIO monitor, the cluster stop working. It seems
>> like the ceph is not updated with the new mon or something
>>
>
> In the doc you quoted, one can read:
>
> "Due to the nature of Paxos, Ceph requires a majority of monitors running
> to establish a quorum (thus establishing consensus).
>
> [...]
>
> For instance, on a 2 monitor deployment, no failures can be tolerated in
> order to maintain a quorum; with 3 monitors, one failure can be tolerated;
> [...]"
>
> And in a box beneath, you also see
>
> "Note:  A majority of monitors in your cluster must be able to reach each
> other in order to establish a quorum."
>
>
> So, say you have 2 monitors and you need a majority of them to be up,
> running, and able to communicate with each other in order to form quorum.
> What's a majority of 2? How many failures can you tolerate?
>
>   -Joao
>
>
>
>
> ___
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> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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Re: [ceph-users] Monitor question

[Joao Eduardo Luis]

On 07/07/2016 04:17 PM, Fran Barrera wrote:

Hi all,

I have a cluster setup AIO with only one monitor and now I've created
another monitor in other server following this doc
http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/ but my
problem is if I stop the AIO monitor, the cluster stop working. It seems
like the ceph is not updated with the new mon or something


In the doc you quoted, one can read:

"Due to the nature of Paxos, Ceph requires a majority of monitors 
running to establish a quorum (thus establishing consensus).


[...]

For instance, on a 2 monitor deployment, no failures can be tolerated in 
order to maintain a quorum; with 3 monitors, one failure can be 
tolerated; [...]"


And in a box beneath, you also see

"Note:  A majority of monitors in your cluster must be able to reach 
each other in order to establish a quorum."



So, say you have 2 monitors and you need a majority of them to be up, 
running, and able to communicate with each other in order to form 
quorum. What's a majority of 2? How many failures can you tolerate?


  -Joao



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Re: [ceph-users] Monitor question

[Matyas Koszik]

Hi,

That error message is normal, it just says your monitor is down (which it
is). If you have added the second monitor in your ceph.conf, then it'll
try contacting that, and if it's up and reachable, this will succeed, so
after that scary error message you should see the normal reply as well.

The important thing is to keep a consistent ceph.conf accross the cluster.

Matyas

On Thu, 7 Jul 2016, Fran Barrera wrote:

> Hi all,
>
> I have a cluster setup AIO with only one monitor and now I've created
> another monitor in other server following this doc
> http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/ but my
> problem is if I stop the AIO monitor, the cluster stop working. It seems
> like the ceph is not updated with the new mon or something
>
> Here I can see two monitors:
> $ ceph -s
> cluster 0817ef6e-233d-41cc-801c-cfb90ed9597a
>  health HEALTH_OK
>  monmap e2: 2 mons at {ceph-monitor-2=
> 192.168.1.10:6789/0,ceph-monitor=192.168.1.11:6789/0}
> election epoch 40, quorum 0,1 ceph-monitor-2,ceph-monitor
>  osdmap e400: 4 osds: 4 up, 4 in
> flags sortbitwise
>   pgmap v832123: 684 pgs, 7 pools, 291 GB data, 38993 objects
> 303 GB used, 3420 GB / 3724 GB avail
>  684 active+clean
>
> But If I stop the ceph-monitor I can see this error:
>
> 2016-07-07 17:11:52.287879 7fc04c1fa700  0 -- 192.168.1.10:0/3737104056 >>
> pipe(0x7fc03c000cc0 sd=3 :0 s=1 pgs=0 cs=0 l=1 c=0x7fc03c002000).fault
>
> Any help?
>
> Thanks,
> Fran.
>


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[ceph-users] Monitor question

[Fran Barrera]

Hi all,

I have a cluster setup AIO with only one monitor and now I've created
another monitor in other server following this doc
http://docs.ceph.com/docs/master/rados/operations/add-or-rm-mons/ but my
problem is if I stop the AIO monitor, the cluster stop working. It seems
like the ceph is not updated with the new mon or something

Here I can see two monitors:
$ ceph -s
cluster 0817ef6e-233d-41cc-801c-cfb90ed9597a
 health HEALTH_OK
 monmap e2: 2 mons at {ceph-monitor-2=
192.168.1.10:6789/0,ceph-monitor=192.168.1.11:6789/0}
election epoch 40, quorum 0,1 ceph-monitor-2,ceph-monitor
 osdmap e400: 4 osds: 4 up, 4 in
flags sortbitwise
  pgmap v832123: 684 pgs, 7 pools, 291 GB data, 38993 objects
303 GB used, 3420 GB / 3724 GB avail
 684 active+clean

But If I stop the ceph-monitor I can see this error:

2016-07-07 17:11:52.287879 7fc04c1fa700  0 -- 192.168.1.10:0/3737104056 >>
pipe(0x7fc03c000cc0 sd=3 :0 s=1 pgs=0 cs=0 l=1 c=0x7fc03c002000).fault

Any help?

Thanks,
Fran.
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