Re: [ceph-users] Two clusters on same hosts - mirroring

[David Turner]

Having a live disk and a DR disk in each node doesn't work.  Ceph places
its data very differently than to expect that the 2 drives in each node
would be a copy of each other.  I'm realizing now that you were talking
about rbd mirroring as being something that would keep a second copy of an
OSD disk on another disk.  RBD mirroring is a very different feature to
that and has nothing to do with physical hardware.

Ceph has redundancy by keeping multiple copies of data and keeping each
copy as far away from the others as you tell it.  The default is to have 3
copies of your data and to keep each copy on a different server.  You can
change that to more copies of your data being kept.  You can also change
that so that each copy will be kept in a different rack from the other
copies.  You can do this in the inverse where it will only keep your copies
on separate disks and can have multiple copies in the same host... just
whatever you need.

There is no such thing as a DR copy of a disk in Ceph.  Ceph is built to be
able to recover from its own disasters by keeping enough copies of your
data separate from each other in different hosts.  Recovering from the loss
of a data drive in Ceph is common and handled very well.  Some people use
RAID 1 to mitigate the need to rebalance, but I see that as waste of space
(at least for all of my use cases).

On Mon, Aug 14, 2017 at 5:15 PM Oscar Segarra 
wrote:

> Hi,
>
> In my test/lab I'm working with a single node just for testing
> functionality... once it works, I will expand this configuration up to 10
> nodes.
>
> I'd like all hosts having a drive for live data and the other for DR and
> backup to tape.
>
> Thanks a lot.
>
> 2017-08-14 22:27 GMT+02:00 Jason Dillaman :
>
>> Personally, I didn't quite understand your use-case. You only have a
>> single host and two drives (one for live data and the other for DR)?
>>
>> On Mon, Aug 14, 2017 at 4:09 PM, Oscar Segarra 
>> wrote:
>> > Hi,
>> >
>> > Anybody has been able to work with mirroring?
>> >
>> > does has any sense the scenario I'm proposing?
>> >
>> > Thanks a lot.
>> >
>> > 2017-08-08 20:05 GMT+02:00 Oscar Segarra :
>> >>
>> >> Hi,
>> >>
>> >> I'd like to use the mirroring feature
>> >>
>> >> http://docs.ceph.com/docs/master/rbd/rbd-mirroring/
>> >>
>> >> In my environment I have just one host (at the moment for testing
>> purposes
>> >> before production deployment).
>> >>
>> >> I want to dispose:
>> >>
>> >> /dev/sdb for standard operatoin
>> >> /dev/sdc for mirror
>> >>
>> >> Of course, I'd like to create two clusters, each cluster with a pool
>> >> "mypool" and enable mirror.
>> >>
>> >> The final idea is using CephFS for exporting to tape my VMs in
>> consistent
>> >> state without affecting production OSD /dev/sdb.
>> >>
>> >> http://docs.ceph.com/docs/master/cephfs/createfs/
>> >>
>> >> Anybody has tried something similar? can anybody explain his
>> experience?
>> >>
>> >> Thanks a lot.
>> >>
>> >>
>> >>
>> >
>> >
>> > ___
>> > ceph-users mailing list
>> > ceph-users@lists.ceph.com
>> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>> >
>>
>>
>>
>> --
>> Jason
>>
>
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Re: [ceph-users] Two clusters on same hosts - mirroring

[Oscar Segarra]

Hi,

In my test/lab I'm working with a single node just for testing
functionality... once it works, I will expand this configuration up to 10
nodes.

I'd like all hosts having a drive for live data and the other for DR and
backup to tape.

Thanks a lot.

2017-08-14 22:27 GMT+02:00 Jason Dillaman :

> Personally, I didn't quite understand your use-case. You only have a
> single host and two drives (one for live data and the other for DR)?
>
> On Mon, Aug 14, 2017 at 4:09 PM, Oscar Segarra 
> wrote:
> > Hi,
> >
> > Anybody has been able to work with mirroring?
> >
> > does has any sense the scenario I'm proposing?
> >
> > Thanks a lot.
> >
> > 2017-08-08 20:05 GMT+02:00 Oscar Segarra :
> >>
> >> Hi,
> >>
> >> I'd like to use the mirroring feature
> >>
> >> http://docs.ceph.com/docs/master/rbd/rbd-mirroring/
> >>
> >> In my environment I have just one host (at the moment for testing
> purposes
> >> before production deployment).
> >>
> >> I want to dispose:
> >>
> >> /dev/sdb for standard operatoin
> >> /dev/sdc for mirror
> >>
> >> Of course, I'd like to create two clusters, each cluster with a pool
> >> "mypool" and enable mirror.
> >>
> >> The final idea is using CephFS for exporting to tape my VMs in
> consistent
> >> state without affecting production OSD /dev/sdb.
> >>
> >> http://docs.ceph.com/docs/master/cephfs/createfs/
> >>
> >> Anybody has tried something similar? can anybody explain his experience?
> >>
> >> Thanks a lot.
> >>
> >>
> >>
> >
> >
> > ___
> > ceph-users mailing list
> > ceph-users@lists.ceph.com
> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >
>
>
>
> --
> Jason
>
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Re: [ceph-users] Two clusters on same hosts - mirroring

[Jason Dillaman]

Personally, I didn't quite understand your use-case. You only have a
single host and two drives (one for live data and the other for DR)?

On Mon, Aug 14, 2017 at 4:09 PM, Oscar Segarra  wrote:
> Hi,
>
> Anybody has been able to work with mirroring?
>
> does has any sense the scenario I'm proposing?
>
> Thanks a lot.
>
> 2017-08-08 20:05 GMT+02:00 Oscar Segarra :
>>
>> Hi,
>>
>> I'd like to use the mirroring feature
>>
>> http://docs.ceph.com/docs/master/rbd/rbd-mirroring/
>>
>> In my environment I have just one host (at the moment for testing purposes
>> before production deployment).
>>
>> I want to dispose:
>>
>> /dev/sdb for standard operatoin
>> /dev/sdc for mirror
>>
>> Of course, I'd like to create two clusters, each cluster with a pool
>> "mypool" and enable mirror.
>>
>> The final idea is using CephFS for exporting to tape my VMs in consistent
>> state without affecting production OSD /dev/sdb.
>>
>> http://docs.ceph.com/docs/master/cephfs/createfs/
>>
>> Anybody has tried something similar? can anybody explain his experience?
>>
>> Thanks a lot.
>>
>>
>>
>
>
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>



-- 
Jason
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Re: [ceph-users] Two clusters on same hosts - mirroring

[David Turner]

I'm sure you can set up 2 different clusters in the same machine and
configure them to mirror RBD's between them.  I do not believe that this
has any usefulness other than learning the commands and testing scripts.
No benchmarking will be useful at all and any problems you run into might
just be because of your configuration as opposed to the actual mirroring.
You probably won't find many people that have done this method to be able
to troubleshoot problems with it.  You are intending to use mirroring
between multiple locations and not just in the same building/data center,
correct?  If you are intending to use 2 clusters in the same building (or
on the same hardware), then mirroring will gain you nothing and just
configuring more replicas will give you the same resiliency.

RBDs have nothing to do with CephFS.  CephFS has no visibility of what RBDs
you are using for VMs so you can't use it to back up RBD data to an
external source.  Ceph's backup solution for RBDs is snapshotting the RBD
and being able to clone the snapshot or restore the RBD to a snapshot.
This doesn't remove the cluster as a whole from being the single point
where your data is, but it is an actual backup of the VM data.  I haven't
heard of anyone backing up RBDs to tape backups before.  My only guess as
to how that would be done would be to create a snapshot of the RBD, cloning
the snapshot, mapping the cloned RBD to a machine that you then back up to
tape.

On Mon, Aug 14, 2017 at 4:09 PM Oscar Segarra 
wrote:

> Hi,
>
> Anybody has been able to work with mirroring?
>
> does has any sense the scenario I'm proposing?
>
> Thanks a lot.
>
> 2017-08-08 20:05 GMT+02:00 Oscar Segarra :
>
>> Hi,
>>
>> I'd like to use the mirroring feature
>>
>> http://docs.ceph.com/docs/master/rbd/rbd-mirroring/
>>
>> In my environment I have just one host (at the moment for testing
>> purposes before production deployment).
>>
>> I want to dispose:
>>
>> /dev/sdb for standard operatoin
>> /dev/sdc for mirror
>>
>> Of course, I'd like to create two clusters, each cluster with a pool
>> "mypool" and enable mirror.
>>
>> The final idea is using CephFS for exporting to tape my VMs in consistent
>> state without affecting production OSD /dev/sdb.
>>
>> http://docs.ceph.com/docs/master/cephfs/createfs/
>>
>> Anybody has tried something similar? can anybody explain his experience?
>>
>> Thanks a lot.
>>
>>
>>
>>
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Re: [ceph-users] Two clusters on same hosts - mirroring

[Oscar Segarra]

Hi,

Anybody has been able to work with mirroring?

does has any sense the scenario I'm proposing?

Thanks a lot.

2017-08-08 20:05 GMT+02:00 Oscar Segarra :

> Hi,
>
> I'd like to use the mirroring feature
>
> http://docs.ceph.com/docs/master/rbd/rbd-mirroring/
>
> In my environment I have just one host (at the moment for testing purposes
> before production deployment).
>
> I want to dispose:
>
> /dev/sdb for standard operatoin
> /dev/sdc for mirror
>
> Of course, I'd like to create two clusters, each cluster with a pool
> "mypool" and enable mirror.
>
> The final idea is using CephFS for exporting to tape my VMs in consistent
> state without affecting production OSD /dev/sdb.
>
> http://docs.ceph.com/docs/master/cephfs/createfs/
>
> Anybody has tried something similar? can anybody explain his experience?
>
> Thanks a lot.
>
>
>
>
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