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.
