WAN accelerator sizing for 4 PB

Userlevel 1

Hi ,

1. How many WAN accelerators are needed for 4PB of data with 500Mbps bandwidth ? 

I have gone through the best practices as well.Didnt got a clear understanding.

2. Can we use WAN accelerators during backup and recovery 1DC or just for replication purpose ? 



Userlevel 7
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Are you sure 4 PB is not your total of the size of your backup? Could you estimate or know the size of a full backup?

Userlevel 7
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I’ll jump in one last time and say the theatrical max is not what you will get either.


I have a 10G link and Veeam does a really good job of pushing data but there are also other things to consider.   Is this your outbound connection for your business? is it a dedicated line? 

Our link between datacenters was getting pretty saturated and we had to limit Veeam to about 8Gbps as if that line gets saturated bad things will happen. (Working on ordering a second line now)


The nice thing is under the hamburger menu, you can go to Global Network Traffic rules and set different throttles for each network Veeam uses.  You can also select time frames if you are not 24/7.


As a 24/7 critical business unfortunately I don’t have the ability to push everything to the evening. 

Userlevel 7
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@Ash19 when working between 100Mbps & 1Gbps connection speeds, you can use WAN Accelerator in high bandwidth mode, which will reduce the actual consumed bandwidth VS the effective throughput.

There are some key differences in how this mode works, such as a lack of global cache. I’d suggest a quick read here:


Unfortunately 4PB of source data is not possible with 500Mbps, WAN Accelerator or not. As Veeam recommend direct connections without WAN accelerator for speeds 1Gbps+, we can assume we won’t see a higher effective throughout than 1Gbps, so taking @Scott’s calculations for 500Mbps and cutting them in half for the POTENTIAL doubling of throughput, you’re looking at a year for the initial upload.


Where are you sending this much data to? A private DC? A cloud object storage provider?

If it’s cloud object storage such as Azure or AWS, you’d benefit from looking at Azure Databox or AWS Snowball for the initial seed, then increase your WAN bandwidth for your incrementals.

Userlevel 7
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Check out the BP guide for WAN Accelerators:

In your situation, according to the guidelines, you would have both source and target set to high bandwidth mode in which case the global cache would not be used.

And, as @Scott calculated, this amount of data will take a long time even using the WAN Accelerators.

Userlevel 7
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I tried a second calculator to make sure I wasn’t out to lunch. This one accounted for 10% overhead. 


Here were the results


A file that is 4 PB would take at least 874 days, 21 hours, 37 minutes, 4 seconds to transfer over 500.000 MBit/s



Userlevel 7
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4PB at 500 Mbps or 62.5 MBps in absolute best case scenario is 740.7 DAYS. 

That is over 2 years!!!!!!


Are you sure you had it correct with Mpbs?


On a 10 Gbps link, it’s theoretical max totally saturating the link is 37 days at 4 PB which will be higher as you will never hit the full max sustained for that long.    


You will need to seed this in advance, but having 4PB, do you know what your daily change rate is going to be? 


For reference, 5TB on a 500 Mbps link is most likely going to run over 24 hours. If you get in to that situation you may never catch up as the jobs will continue to pile up. 




Userlevel 7
Badge +19

And with that amount of data, be aware of the Global Cache config for your Accelerators. You can read more about that here.

Nice find on the WAN Acc. Guide Chris. I wasn’t aware of that! 😊

Userlevel 7
Badge +21

This link should help with sizing - WAN Accelerator Sizing - User Guide for VMware vSphere (

Also this link - KB1877: WAN Accelerator Quick Reference (