If the bottleneck is your network, then increasing hardware (adding drives, cpu, or memory) will not have much of an affect, nor will segregating the data.  If the botteneck is network, then I would suggest utilizing FC.

There are several specifics to a configuration you have not mentioned which affect performance:

1. Speed at which data is delivered to the media server / How fast can the clients deliver data to the media server. (often limited by client disk speed)
2. Speed at which tape drives can ingest data / What is bandwidth of tape drives individually and collectively. (what method are you using to write to tape over ethernet?)
3. Influence of other (Non-Netbackup) I/O intesive work on the Media Server
4. Network configuration/congestion - Is this really a dedicated (direct) 1Gbps ethernet link or is it through a network of shared switches.
5. Netbackup configuration - Are you using multiplexing?

Basically, you have to specify details of your configuration in order allow hypothesis on your bandwitdth restrictions.

 There are some tweaks in the NBU tuning guide found on the support pages for download.  Mainly for network buffers...

You could trunk your Gb links on your media server for more bandwidth to receive more data in parallel.

Are you using jumbo frames on a dedicated backup network?  Perhaps think about it, since most servers have a 2nd NIC not in use in 75% of the customers I run into.

That is a goodly amount of data, how many files is it roughly?  Netbackup doesn't like millions of files at all.

Have you considered going with Synthetic backups?

Flash backup can do magic in backing up files more in count

check the admin guide to know about it

It's a separate solutions but you can performe all of them together:
1. Create a trunk on Media server no increase LAN speed.
2. Use SAN-clients for backup (it's a better solution)
3. Use DSSU to perform a bakcup during weekend and after that you can relocate this images to tape.
4. If you using LTO3  upgrade up to LTO4.
6. If you using 1G insure that you enable jumbo-frames.

According to my observation Gigabit Ether net trunking is not an option for backup. We tentatively installed this configuration on one of our Oracle DB clients, but that didn't helped to boost the backup performance.
I think the better solution is to :
a) convert your client to SAN media server
b) use 3-4 LTO3 or, better, LTO4 drives to backup this SAN media server.

Please don't forget to tweak NetBackup buffers on that SAN media server.
I presume you are already familiar with NetBackup Tuning Guide.

I agree with Garilov...
6 TB of data is quite a lot for any one client, no matter how large our NetBackup environments are.
If had to backup 6 TB every night, then I'd definitely be looking at adding some HBAs to the client, getting some NetBackup SSO licences and sharing with the normal media servers.

1 Gb/s
1000 Mb/s
125 MB/s
60% efficiency
75 MB/s max practical
 
6 TB
6,144 GB
6,291,456 MB
83,886 seconds
23 hours

Based on these numbers you'll be lucky to get the job completed in 35 hours, let alone 23 - as the above assumes that the disks + the client + the LAN + the media server + the SAN + the tape drives are all not busy doing other things - and it is highly unlikely that even just two of these components are idle at any given time.

Also consider, if it's 6 TB now, what will it be next year, and the year after that.

IMHO - a bigger box for the client, two HBA ports per fabric (e.g. two dual port cards), 4 x LTO4 (i.e. 2 x LTO4 per fabric), and very carefully balance the file systems and disk groups with your NetBackup policy path selections and/or database elections - you'll need to work very closely with your DBAs.

Pay careful attention to the "Backup Planning Guide" - and consider how busy the client hardware will be supporting all this additional work load - i.e. how much CPU, RAM and disk space you need just for NetBackup.

HTH,
Dave.

I would aim to complete the backup in under six hours, to allow for maintenance windows, down time, day to day problems, backup re-runs, restores, other works on either client, media server, LAN, SAN, library, tape drives, O/S upgrades, S/W patches, firmware updates, etc etc - i.e. someone else will always be delaying your backups!

90 MB/s per LTO4 practical
4 drives
360 MB/s
2880 Mb/s
2.81 Gb/s
 Therefore 2 x 4 Gb/s FC paths are required for redundancy
 
6 TB
6,144 GB
6,291,456 MB
360 MB/s
17,476 seconds
5 hours

Also, reading above, it still wasn't clear to me how many files are involved.  Someone else picked up on this too.  If this is one huge database server then it's probably not an issue, but if this is a file server with millions or even tens of millions of small files, then you will highly likely need to use the FlashBackup capabilities of the Snapshot Client option (which is within the "NetBackup Enterprise Client" licence).

HTH.

One final point - NetBackup does scale!  It just takes time to work it all out.

You will have to do your math for each stage of data producer (clients) and data consumers (media servers) - or in your case both in the same box (i.e. the client itself) - and think about the performance profile, capabilities and limititations of each single component/stage/hop along the entire data path end-to-end, e.g.:
disks - RAID - shelves/controllers/heads - storage HBAs - SAN path - switch - SAN path - client HBAs - CPU/memory - NetBackup buffers - client HBAs - SAN path - switch - SAN path - tape HBAs - tape drives - tapes.

A word of advice - do not be tempted to zone both your FC disk and your FC tape through the same HBAs.  I believe that the standard recommendations still are not to mix disk and tape traffic.  So, I recommend additional separate HBAs in the client specifically for backup traffic to tape.

An example of scaling, we have four media servers - each has:
NICs - Eight - in a 2 trunks of 4 Gb/s in IPMP failover config.
HBAs - Seven dual port HBAs - i.e. 14 FC connections per media server - thus 7 on each fabric.
Zoning - Carefully patched and zoned so that all backup SAN traffic always stays within the ASICs of the SAN switches - i.e. the backup FC traffic never enters the backplane of any SAN switch nor does the backup FC traffic traverse switch to switch.  We have disk storage arrays, VTLs and tape libraries connected to our media servers hence the number of FC connections in each.  There are four media servers as we determined that site resilience, site H/A and site DR were all important factors.

Your business requirements may well be different.
6 TB of data is not inconsequential.
Good luck.

Ok.
Look, you have 3  X 1G  NICs (3 VLANs). What speed do you get for this NICs? Something about 3X50(MB)=150 MB/sec. Speed between Media-server and TapeLibrary is 360 MB/s. As you understand speed between clients and mediaserver isn't enough. You have to increase a  LAN speed  for example by adding new NICs (Adding Quad Ethernet card is a cheapest way) or use SAN-client/SAN-media server  (it's more expensive).

P.S. Have you check your Pramble size?

The simples way to increase your perforance is sit down, draw your topology, mark every link (LAN/SAN) and write it's theoretically  speed. Most bottlenecks  will be filtered on this stage. Next step - begin test every link to understand is it new  bottlenecks? What is the way to make it better?
If you want us to do it draw the picture of your environment, mark the connection speeds and we'll look at it.
Now we are just cheating and do nothing :)

with LTO-4 it should be an achievable goal, you'll need to maximize I/O

we run netbackup on a Proliant DL380 G5 server. it's i/o is around 3gbps. g6 servers are double that. a cheapo G6 server will run $2500
we use 2 gigabit NIC's teamed together
for the clients teaming Gbps NIC's will also help a lot
we're an HP shop but the tech is pretty much all the same no matter who you buy from. G5 servers have much faster I/O than G4 or earlier generation. upgrading your clients to G6 servers which is what is out now will speed up your backup times.