[aklug] Re: need a way to communicate 10TB of storage

From: Shane R. Spencer <shane@bogomip.com>
Date: Thu Mar 31 2011 - 15:37:50 AKDT

I've had to describe this as well to companies because of a disaster recovery product I'm
building. I'm using time deltas to help people realize the incredible slowness their cloud
based backup and restore solutions will achieve over the fast network they rely on so
much. (Stupid lower 48 and their super high speed connection grubbing)

Assuming 1 megabit full duplex and TCP all the way (just assume 20% flies out the window
as a worst case scenario):

  (((1 * terabyte) / ((1 * megabit) / second)) / 0.8) = (x * day) = approx. x = 115.74074

This doesn't fit into most peoples time budget for time it takes to get back important
data. This is where off-site backups come in handy... however small businesses are
storing a heck of a lot of information lately and would like an option other than bogging
down their home DSL with nightly backups.. which is what I'm working on at the moment. To
me it's faster to use the USPS than it is to restore this amount of information over the
Internet. However many companies now have 10mb/s lines that average around 8mb/s on a
stream.. lets see what Mr Math says.

  (((1 * terabyte) / ((8 * megabit) / second)) / 0.8) = (x * day) = approx. x = 14.467593

Ok.. 14 days is a lot better than 115 days. Still not enough however.

In order to beat the USPS you would need approximately 60mbit dedicated and fully
available to your restore process for 1.92 days. For an overnight curiour (16 hours) you
would need a 200mbit connection.

Using UDP however and a transport layer I'm working on you can take that 20% packet waste
and bump it down to around 1% for arguments sake and shave a few days off. It's
impressive thinking about transfers in days.

  (((1 * terabyte) / ((1 * megabit) / second)) / 0.99) = (x * day) = approx. x = 93.527871
  (((1 * terabyte) / ((8 * megabit) / second)) / 0.99) = (x * day) = approx. x = 11.690984
  (((1 * terabyte) / ((60 * megabit) / second)) / 0.99) = (x * day) = approx. x = 1.5587979
  (((1 * terabyte) / ((200 * megabit) / second)) / 0.99) = (x * day) = approx. x = 0.46763936

On 03/31/2011 12:26 PM, Jason McEachen wrote:
> So a reporter asked me for a way to explain what 10TB of storage is.
>
> Got any cool "conversational analogies" for that amount of data?
>
> I found in various places:
> 800,000 phone books
> 16,000 music CDs
> the library of congress (books)
> 1400 movies (assume 700M)
>
> Thanks for any better illustrations,
>
> --Jason
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Received on Thu Mar 31 15:38:00 2011

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