ONTAP Hardware

Backing up 32TB to a Tape Library



One of our partners is aksing the following technical question that I need help with:

They need to spec a tape backup for a FAS3240AE with 240x300Gb drives and Complete Bundle.  There is 32Tb data with a backup window of 12 hours. The backup software will be BackupExec 2010 with the NDMP Option.

Do we have any information on the throughput for the controller or how to work it out in this situation?





Wow, that's a tight schedule.

Considering LTO5 and its very theoretical speed of 140 MB/s you get 500GB/h, that's about 5.8TB in 12 hours.

And this is very, very, very theoretical.

Some thoughts:

- Does your partner need full backups every night?

- Is the full backup window really only 12 hours?

- Quit backing up via tape. Consider backing up to a remote filer (ProtectionManager, SnapVault, DeDup, etc.). This is probably much less expensive than a large library running LTO5 tape drives plus maintenance costs for hard- and software.

That's all I can think of right now. Hey, it's friday afternoon...




Thank you for your answer.

The plan is to use 6 LTO-5 drives split between two controllers but we need the figures to work out what throughput we can get.

As they have a FAS3240 with 240 drives I thought I would run the PQR report on the FAS3210 as this is limited to 240 drives, so I know the backend specification would be the same, and I know that the 3240 has more core and memory, so “in theory” the throughput levels should be achievable by the FAS3240.  This is what I got:

==>Large Sequential Read IO (in MB/sec), Flexible Volumes - Protocol FCP - Transfer Size 64KB - FAS3210c 1712

This is a very nice figure but do you think it would be reality if they were attaching half the LTO drives to one controller then the other half to the other controller?



Go back and ask how many files are in the 32Tb.  If it is millions you have no chance as NDMP will still be cataloging the directory for 12+ hours!  {You could also look at splitting up the data into qtrees so that you can run multiple simultaneous backup jobs.}

You could also ask them to NDMP dump to null.  This will tell you how fast the filer could send the data to tape, in a perfect world.  If the system can do it in 12 hours it is time to start looking for fast tape drive and possible multiplexing.  But if the system can not read the data fast enough, there is no point looking at writing to tape.

We have tight windows here so we changed to Snapvault and then NDMP in the background with no time limit.  Much happier now.

Hope it helps



Hi Brendon,

First of all -- Thank you ver much for helping me with this ...

Before I received your last reply the customer sent me the following. => I will send them the information on your last reply and ask them how many files in 32TB.


I'll just add a little here so that we can work out how many Tape Drives we need to supply to exceed the 12 hour backup window here.

We have 32TB of data to be backed up which equates to 2.67TB per hour to achieve a 12 hour backup window.

Each LTO5 drive operates at a maximum transfer rate of 140MB/s which give a throughput of up to 504GB per hour.

Realistically we need to be backing up data at a rate of around 3TB per hour which equates to approx 6 tape devices, taking approx 10 hours to back up these devices.

The FAS3240 has 2 x 4GB/s FC Ports on the controllers, effectively giving you 2 x 400Mb/s connections to the tape devices. So each controller will be able to stream to 4 tape devices simultaneously (4 x 140MB/s = 560MB/s, allowing for tape changes etc), so potentially we could stream to 8 tape devices via the FC HBA ports on the controllers, assuming the tape devices were connected to a dedicated tape SAN. If we use this configuration we need to provide Host FC HBA Ports in one of the expansion slots to ensure we have host connectivity, as we can't use the onboard ports if these are used for Tape connectivity. (Elias - Hence the need for 4 x FC Ports per controller, not the 2 we have to use on the FAS3200 series, and Ideally running at 8GB/s as most new devices such as LTO5 Drives and now available with 8GB/s fibre - Subtle dig over Matey 🙂 )

So to back up the 32TB of data we need the following additions:-

2 x Brocade 320E SAN switches with at least 8 ports licensed, Full Fabric Licensing

Tape Library with 6 x LTO5 FC Attached drives. Needs to be expandable above 6 drives.

Selection of blank media (each backup will use approx 22 tapes [assuming 1.5TB per tape])

2 x LTO5 Cleaning tapes.

2 x Dual Port 8Gb/s Target Host adapter cards for FAS3240's - To provide Host Connectivity for the FAS3240.

10 x 5m LC/LC Multimode Fibre Patch cables (OM3 - 125/50)

Thank you very much for your assistance,



I was wonder whether SnapMirror to tape/over FC will be another option?

Good luck