Re: Ceph mount rbd

[Jason Dillaman <jdillama@xxxxxxxxxx>]

... additionally, the forthcoming 4.12 kernel release will support non-cooperative exclusive locking. By default, since 4.9, when the exclusive-lock feature is enabled, only a single client can write to the block device at a time -- but they will cooperatively pass the lock back and forth upon write request. With the new "rbd map" option, you can map a image on exactly one host and prevent other hosts from mapping the image. If that host should die, the exclusive-lock will automatically become available to other hosts for mapping.

Of course, I always have to ask the use-case behind mapping the same image on multiple hosts. Perhaps CephFS would be a better fit if you are trying to serve out a filesystem?

On Wed, Jun 28, 2017 at 6:25 PM, Maged Mokhtar <mmokhtar@xxxxxxxxxxx> wrote:

On 2017-06-28 22:55, lista@xxxxxxxxxxxxxxxxx wrote:

Hi People,

I am testing the new enviroment, with ceph + rbd with ubuntu 16.04, and i have one question.

I have my cluster ceph and mount the using the comands to ceph in my linux enviroment :

rbd create veeamrepo --size 20480
rbd --image veeamrepo info
modprobe rbd
rbd map veeamrepo
rbd feature disable veeamrepo exclusive-lock object-map fast-diff deep-flatten
mkdir /mnt/veeamrepo
mount /dev/rbd0 /mnt/veeamrepo

The comands work fine, but i have one problem, in the moment, i can mount the /mnt/veeamrepo in the same time in 2 machines, and this is a bad option for me in the moment, because this could generate one filesystem corrupt.

I need only one machine to be allowed to mount and write at a time.

Example if machine1 mount the /mnt/veeamrepo and machine2 try mount, one error would be displayed, show message the machine can not mount, because the system already mounted in machine1.

Someone, could help-me with this or give some tips, for solution my problem. ?

Thanks a lot

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You can use Pacemaker to map the rbd and mount the filesystem on 1 server and in case of failure switch to another server.

 

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--

Jason

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