1. In Navisphere Express click snapshots on the menu then Prepare New Snapshot.
2. In step 1, select the virtual disk you want to backup, in step 2 select the backup server, and click apply.
3. Clcik View all snapshots and wait until the snapshot's state is Ready.
4. On the production server use the Navisphere Server Utility GUI and Start a Snapshot, you will need to specify the source virtual disk
5. On the Backup server use the Navisphere Server Utility and Allow Access to a Snapshot, you will need to specify the virtual disk and assign it a drive letter.
6. The Backup server will now have access to the snapshot.  The production server will be able to continue writing to the virtual disk, and the backup server will be able to back up the data at the point in time you started the snapshot on the production server.
7. After the backup is complet; on the Backup server use the Navisphere Server Utility and Remove Access to a Snapshot, you will need to specify the virtual disk.
8. On the production server use the Navisphere Server Utility GUI and Stop a Snapshot, you will need to specify the source virtual disk

You would perform steps 4-8 each time you want to perform a backup.  There is another option to script the commands these have been posted in the FAQ section of the website.  Here is a direct link to the procedure.

Your wording worries me a bit. I hope you're not trying to say that you're using the AX150i SAN with 1 virtual disk and having 5 servers attached to share this 1 virtual disk?

If so, unless you have a 5-node cluster, you'll need that backup more and more likely the longer you wait.

A SAN isn't the same as a NAS. You can give the disk space to a server, which in turn can share the disk space to multiple systems/users using shares (sometimes referred to as NAS-on-SAN), but you cannot have the AX150i give disk space to multiple servers unless they are clustered (the warning that comes up when you select a 2nd server or multiple servers when you try to assign disk space is for a reason).

Unless there is a piece of software that regulates who (which server) writes to the disk at which time, you'll run into a point where 2 servers are overwriting eachother's data changes and your data will be gone.

This is NOT a NAS. It is a SAN. It may be the same 3 letters, but they have a completely different meaning.

A NAS gives file level access to data using a sharing protocol (e.g. SMB or NFS). The OS of the NAS controls which user can access the file (2nd user to access a file at the same time would get read-only access at best).

A SAN gives block level access, which means the server that's been given the disk space can do whatever it wants with the diskspace (e.g. format the whole disk) without any reservations.

If you want to read more details about the differences between NAS and SAN, you may want to consider checking this book out.

In your case your SAN goes over ethernet instead of fibre channel, but that's just the carrier of the signal, it doesn't change the SAN into a NAS.

Each server should have it's own dedicated disk space unless the servers are clustered. If you then want to do backups using the snapshots (and you have the 20% unused space needed/recommended for snapshots), you'd present the snapshots to the backup server. Changes that are made to the snapshot aren't pushed to the production virtual disks, which is why it's safe (and required) to give snapshots to a server other than the server that owns the original virtual disk.

When you select to create a snapshot, the system will take the virtual disk size, then take 20% of this and reserve this from the diskpools (not from the existing virtual disk(s)). It actually creates mini virtual disks of 10GB each and puts these in a pool called Snapcache (check the EMC documentation about Snapview). These won't take away from the diskspace you've opted to create, but they do take away from the disk space you will have available to create virtual disks for your server(s).

Example:
- AX150
- 4 x 500GB drives
You create a single diskpool of these first 4 drives and make it a raid 5. This yields about 1337GB's worth of space. You create 5 x 200GB of virtual disks. You want to be able to snap all 5 of these. This means you need 5 x 20% x 200GB = 200GB for snapcache.

If, however, you were to create 5 x 250GB in virtual disks, you use 1250GB, leaving about 87GB (really just 80GB as snapview uses 10GB snapcache luns). This could still work, but it may be better not to run 5 snapshots simultaniously.

• How many and what size hard drives are in your AX150i?
• How many and what size virtual disks have been created?
• What size is the virtual disk you are trying to create a snapshot of?