FlexClone Query

[ittechnical]

Hi, we have a document management system and I want to make a copy of the physical datastore which is created as a volume on our netapp.

If I use flexclone do I run any risk of losing any data from the existing volume

Many thanks

[ASHWINPAWARTESL]

No. There are no risks. As you may be aware behind FlexCone it's the NetApp's unique (Redirect-on-wrte) ROW  snapshot technology that is being used, which creates an online, read-only copy of the entire file system. In other words, the existing data remains read-only and hence secured. FlexClone volume (based on the snapshot) and its parent volume share the same disk space for any common data. This means that creating a FlexClone volume is instantaneous and requires no additional disk space (until changes are made to the FlexClone volume or its parent).

TR3347 is a good read in this context.

or,

http://hd.kvsconsulting.us/netappdoc/801docs/html/ontap/smg/GUID-284A0B23-DE4D-4E97-B333-EF4646D2CB1D.html

[ittechnical]

Thanks for the reply, sounds good, I made the flexclone and pointed our test dms at it which works fine thanks

Does this mean now the original volume becomes read only? It still allows me to create documents which is good because otherwise this would have stopped it working properly, the live DMS..

Also does this mean when data is accessed from the flexclone it pulls data from the original and stores it separately in the cloned volume?

Many thanks

[ASHWINPAWARTESL]

You'r welcome. Well, I think the TR I pointed to you is good starting point. It covers all the queries you have in your mind. Coming specific to your question -

Does original volume becomes read-only ?

Answer :NO! Both the parent (flexvol-original) and the cloned (flexclone) volume is read/writeable. Cloned volume is nothing but a point in time copy (snapshot) of the parent volume. When you attempt to add or modify/update the existing data on the original (flexvol) or the cloned (flexclone) volume that it will start consuming the disk space. From this point onwards, both volumes functions independently.

Does this mean when data is accessed from the flexclone it pulls data from the original and stores it separately in the cloned volume?

Answer: No! Cloned volume does not require any extra space, at the time of creation, both flexvol and flexcloned volumes are looking at the same data blocks. (This is block sharing NOT block copying).

I suggest you to look at this post - how "snapshot technology" works, I suppose you will be able to better understand/appreciate flexclone technology:

please read this, how snapshot works: (My favorite)
https://communities.netapp.com/community/netapp-blogs/the-it-corner/blog/2012/03/13/are-all-snapshots-created-equal

Because snapshots share blocks with the active file system data, the clone does not require any additional disk space .The clone occupies the same blocks as the active file system data. When new data is written new blocks are allocated and used to store the new data. The clone and parent share common data blocks, but from that point forward, each functions independently.

[RAVI_PALADUGU]

That's a very good description from Ashwin. But when he said "read-only" it mean the parent volume is not going to get affected due to the writes performed on flexclone. Please find the link for better understanding of flexclone technology

https://communities.netapp.com/docs/DOC-10323