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Question about limitations of NDMP policies for Replication Director

Created: 10 Oct 2012 • Updated: 12 Oct 2012 | 6 comments
ddm2's picture

Hello,

on the Replication Director guide, pag 114, I read:

"Volume snapshot replication of qtree and non-qtree data is not supported."

Can someone explain what does it mean?

 

Thanks

 

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Nicolai's picture

Source: http://www-01.ibm.com/support/docview.wss?uid=swg21125802

 

A qtree is a special subdirectory of the root directory of a volume that gives greater flexibility when storage needs do not demand multiple volumes. Volumes are themselves considered a qtree and can be the target of qtree commands. Therefore, it is recommended to use qtrees from the start.

For more information, refer to the following url, http://www.netapp.com/library/tr/3111.pdf.

Assumption is the mother of all mess ups.

If this post answered your'e qustion -  Please mark as a soloution.

ddm2's picture

Thanks for your answer.

I have a little or no knowledge of NetApp technologies, but I have an ideda of what a qtree is. This explanation is very clear:

http://www.wafl.co.uk/qtree/

But I can't understand the meaning of the sentence in the guide.

"replication of qtree and non-qtree data is not supported".

What does it mean?

Can't I replicate source volume of mixed type?

Can't I replicate from a qtree volume to a non-qtree one?

Thanks. 

RLeon's picture

Essentially, with Replication Director, you can create NetApp snapshots through two ways. The first way is through OST, and the second way is through the NDMP host (that is itself part of the nas).

The OST method do things from the mount point's perspective. I.e., you have to specify a client with Netbackup 7.5.x installed in the client tab.
The NDMP method do things from the NAS/NDMP perspective. I.e., you specify the NDMP host in the client tab.

The OST method snapshots do not have as many limitations as those created using the NDMP method.
One of this limitation is "replication of qtree and non-qtree data is not supported".
This is just a long winded way of saying that NDMP based snapshots cannot be replicated using a "replication operation" in a SLP.
NDMP based snapshot backups also have some annoying restore limitations.

About the only good reason I could think of for using NDMP based snapshots would be that you want the NAS to write the backup directly to tapes, and not having to go through a Nbu media server.
With the OST method snapshots, you cannot tell the NAS to write directly to tape. Only a NDMP host has that ability. But then, you can tell it to replicate its snapshots to another NetApp NAS without having to go through a Nbu media server.

RLeon

ddm2's picture

Thanks for your answer.

Are you saying that NDMP policy type doen't support snapshot replication?

How can I repicate a snapshot to the destination target if I can't use a replication operation?

Thanks.

RLeon's picture

Are you saying that NDMP policy type doen't support snapshot replication?

I think that is what the document is saying.
"qtree and non-qtree" might as well be "every type of volumes".

How can I repicate a snapshot to the destination target if I can't use a replication operation?

As I said, if you are using the OST method, you will be able to use the "replication" operation as one of your SLP steps. If you are using the NDMP method, the "replication" operation in your SLP won't work.

ddm2's picture

Hello RLeon,

 

a customer reported he was able to run a snapshot replication using NDMP policy type. I think this operation is supported but not yet well documented. 

Is there any Symantec employ who can confirm it?

Thanks and regards.