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MSDP Configuration.

Created: 29 Oct 2012 • Updated: 12 Dec 2012 | 7 comments
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I am planning for taking backups through MSDP. But need your inputs on below points before finalizing,

1) How to Share MSDP storage server? Ex: If i take backup through Media Server (M1) and then it crashes, is there any way to restore it without making M1 server up and running.  As in tape there was an option to change to restore after bpmedia -movedb.

2) In our setup there are many Media Servers. Do i need to assign individual storages to each and every Media Servers?


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Nicolai's picture

1: You will need to setup replication between MSDP servers before going into production. Do not rely on a single copy - If a MSDP crashes badly you don't have any backup data at all.

2: See . Yes you do - unless there are details to the qustion I don't know. Since MSDP is very I/O intensive make you use hardware that do the job.

Assumption is the mother of all mess ups.

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Mark_Solutions's picture

MSDP is not like PureDisk in that it does not have a global de-dupe pool

Each Media Server holds its own de-dupe database and as such holds its own disk area that it is contained on

So if you lost a media server you would not have access to the data held on it and would have to get it back up and running to access it again

You would need to assign a storage unit (de-dupe disk pool) to each media server but you could back up to a storage unit group that included them all - the exception being if you plan to use AIR to duplicate between Master Servers in which case you cannot use Storage Units groups

So a summary .. each is independant and owns the disk and database so there is no failover in the way you are thinking

Hope this helps

Authorised Symantec Consultant

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Sahil Joshi's picture

Thanks Nicolai and Mark..! Now things are getting more clear.

Two more questions,

For AIR, can i perform AIR for multiple media servers on to a single Media Server on a Remote Netbackup Domain. Meaning Source Media Servers would be many and Target Media Server would be One. Is it possible?

And, can MSDP be created for a FT Media Server. (We do not have any FT media Server in our setup but if it supports i can think of exploring that option).


Mark_Solutions's picture

No problem with many to one using AIR - but do remember if using AIR you cannot use storage unit groups in the source domain so jobs will have to be targetted at particular media servers

Also no problem with your media server supporting FT as long as the usual pre-reqs are met

Authorised Symantec Consultant

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Nicolai's picture

There are some recommendation for using AIR  - below is taken from "Best practices for using Storage Lifecycle Policies and Auto Image Replication in NetBackup 7.1".

Auto Image Replication is primarily intended to provide a level of site disaster recovery by allowing selected, mission critical backups to be copied between sites electronically. This feature can handily replace previous site disaster methods, which can be cumbersome and limited: 
· Physically moving media (tapes) to off-site storage. 
· Performing a catalog recovery at a remote site. (Does not support spoke-hub environments.) 
· Writing scripts to import images that have been sent by various means such as physical tape or disk replication. 
All of the best practice considerations for SLPs also apply when using Auto Image Replication but there are also some additional factors to bear in mind and these are discussed in the following sections. 
In particular it is important to remember that there are limits to the amount of data that can be copied between domains. Do not use Auto Image Replication to duplicate and replicate all of your data offsite unless you have done a thorough study and upgrade of your storage and network bandwidth requirements in order to support such a load. 
As with SLPs in general it is essential that you ramp up slowly, starting with only a portion of your backups and slowly adding more. 

Assumption is the mother of all mess ups.

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

RLeon's picture

How to Share MSDP storage server?

Multiple Media Servers can send deduplicated data to the same Storage Server.
But that's not what you mean.
You are asking whether it is possible for a Media Server to fail (say the host hardware exploded) and yet its Deduplication Storage Server could still be accessed by other surviving Media Servers for backups and restores.
It is possible, but not when the Deduplication Storage Server is running on the same host as a Media Server.

To understand what that means, know that a "Storage Server" is logically a separate server from the traditional Media Server. Symantec just so happens to make it share the same host with the Media Server; regardless if the host is physical or a VM.
(There are exceptions, however. Please read further down.)
The "MSDP" you query about is called MSDP (Media Server Deduplication Pool) because the Storage Server shares the same host with the Media Server, which makes it looks as if the Media Server manages the Deduplication Pool.
But it doesn't. The Deduplication Storage Server does.
It is just that this Storage Server resides on the same host as a Media Server that they call it MSDP.

I'm sure you know what a Media Server does, but what about a Storage Server, and why is it logically separated from the Media Server?
Well, its only purpose is to manage "special" data storage; in this case, we are talking about deduplicated-data storage.
A Storage Server has its components, db and services. But just know that its only job is to manage the deduplicated data that it receives.
A Media Server or Nbu Client communicates with a Storage Server through the OST API. (Important)

It should be pointed out that a Storage Server does not deduplicate the data that it receives.
To put it in another way, you can only send already-deduplicated data to the Storage Server.
So who deduplicates the data and send it to the Storage Server?
  - The Media Server does, when you use the default mode which is Media Server Deduplication.
  - The Nbu Client does, when you use Client Side Deduplication.
Note that the 1GB memory per 1TB deduplicated data requirement mentioned in the Dedup Guide applies to the Storage Server only.
It does not apply to the Media Servers or Nbu Clients that deduplicate data. (Although a little bit more RAM would be nice).
It is the processor resources that get used up on the deduplication hosts, during, well, data deduplication.

With the above points made clear, it is not difficult to see that, if the Storage Server could somehow be detached from the Media Server and put on to its own dedicated host, you could achieve what you are essentially asking for:
If one Media Server fails, other Media Servers could still read/write the Deduplication Pool, which is managed by a dedicated Storage Server.

Currently, with the software based Netbackup installer, Symantec has not provide a way to install the Storage Server as a dedicated entity on its own host. The Storage Server has to exist together with a Media Server.
I'm not sure if this capability will be provided in the future.
A dedicated Storage Server is certainly beneficial, and it is not impossible to implement; in fact, it already exists in the form of the 50xx Netbackup Appliance and other OST compatible storage devices.
I think it can be unlikely that Syamntec will let you deploy manually a dedicated Storage Server for that exact reason: that this feature already exists in the form of the 50xx Netbackup Appliance and OST compatible storages device.
Note: I'm not talking about the 52xx Appliance, which is very different.

Essentially, the Netbackup 50xx Appliance (and other OST compatible storage devices) is a dedicated Deduplication Storage Server with its own disks (Deduplication Pool).
You can associate multiple Media Servers with it; if one Media Server fails, other Media Servers would still be able to access the Deduplication Pool. Which is basically what you are looking for.
The 1GB memory per 1TB deduplicated data requirement does not apply to the Media Servers in this case, because they are not "together with" the Storage Server anymore.
When you use Client Side Deduplication, the clients will send data directly to the Appliance, skipping the Media Servers. (Remember the part I said about both Media Servers and Nbu Clients could send deduplicated data to the Storage Server via the OST API? This rule applies here nicely.)
You have to make sure that the Client Side Deduplication clients have a network path to the Appliance because of this.

Unless you are using the 50xx Appliance, PureDisk PDDO Mode (phasing out), or other OST compatible storage devices, to achieve some form of high availability, you just have to optimized-duplicate backup images from one MSDP to another, as others have already pointed out.

Marianne's picture

MSDP images can be imported. 

See my own experience:

Please bear in mind that each media server can only have one MSDP disk volume. So, you will not be able to import on another MSDP media server.

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