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Dipbosse

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Dipbosse

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December 4th, 2017 23:00

Testing replicated NFS shares on Unity

Hi all,

IHAC who is looking for the following replication scenario -

They have a prod site and a DR site both with Unity arrays. The prod site has a production NAS server with a bunch of FS and NFS shares mounted on it. They want to replicate only two of the FS to their DR site and test the data from the replicated FS on their DR servers (read only, no writes). They don't want to bring down the prod nas server, simply pause the replication for the nas server and the two concerned FS. Is this something that could be done?

From my understanding of the way the replication works, you would ideally have to failover to the DR site - but since they are replicating only 2 FS, a failover would bring down all the FS mounted on that nas server. I remember there was a way we would do this for CIFS on the older VNXs (not recommended of course), but I'm not certain about the Unity. Any ideas?

Any help would be appreciated! Thanks!

Diptish

  • Rainer_EMC

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    Posted December 5th, 2017 04:00

    CIFS access to a destination mode (readonly target of an async replication) NAS server is currently not possible

    On VNX this was done via DM global CIFS server - which doesnt exist in the Unity multi-tenancy architecture of separate NAS servers

    After a failover of course the destination assumes the identity and you can access using CIFS

    What you can do with the current VNX OE in order to check the replication side or restore files is:

    - configure ftp/sftp and access via winscp - this way you can easily browse through all file systems and snapshots of a NAS server. since you cant authenticate using a CIFS account on the dst without a running CIFS server easiest way is to use local account via passwd file

    - use ndmpcopy if you want to restore/copy data to another Unity system or NAS server - especially useful since ndmcopy copies both CIFS and NFS attributes and ACLs.

    - access via NFS - but you first need to create a read-write snapshot before you can export it via NFS from the dst NAS server

    Remember that in order to access the dst NAS server you also need an active interface there.
    The way to get one is to configure an interface of the type "backup/DR" on the src NAS server - this config will replicate to the dst NAS server and the interface will work there when the dst NAS server is in destination mode

    For the next major release - currently in beta - a readonly CIFS access is planned via a new proxy NAS server functionality

  • Dipbosse

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    Posted December 5th, 2017 04:00

    Thanks so much for your reply Rainer!

    My scenario here involves only NFS and no CIFS. I was just trying to understand better.

    So if I understand correctly,

    I'm replicating the NFS file systems and the NAS server from one Unity to another Unity.

    On the source Unity I have an active backup/DR interface set up which replicates to the dest unity.

    I'll need to create a r/w snapshot which from the dst NAS server which I can export via NFS.

    Is that correct? Or am I missing something here?

    Also the winscp method, would that work with NFS as well, or is it just for CIFS?

    Thanks once again!

  • Rainer_EMC

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    Posted December 5th, 2017 06:00

    yes - for each file system or snapshot you want to make available you would have to manually create a protocol (read-write) snapshot before you can NFS export it

    reason is that on the DR side Unity will currently not allow you to NFS export a readonly object

    scp/ftp is a seperate protocol - it uses Unix attributes but you can access CIFS data through it as well

    see the VNX manuals - they explain it nicely and it mostly also applies to Unity

  • Rainer_EMC

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    Posted December 5th, 2017 06:00

    I would suggest to install two Unity VSA's and try it in your lab

    then it will become clearer than on paper

  • Dipbosse

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    Posted December 6th, 2017 07:00

    Thanks so much Rainer, I will try the VSAs in the lab. Really appreciate you on ECN all the time!

  • Rainer_EMC

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    Posted December 6th, 2017 08:00

    you're welcome