

Thoughts on Glacier pricing - cperciva
http://www.daemonology.net/blog/2012-09-04-thoughts-on-glacier-pricing.html

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jedberg
My favorite part of this whole writeup was:

"Epilogue: They each blame the other for the increased bill they're receiving
from Amazon, leading to a breakdown in their relationship, and they get
divorced a few months later. It was inevitable anyway: Cryptographers never
really trust anyone."

Other than that, I think this whole post is spot on. The product pricing is
clearly not in line with everything else they do.

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cperciva
I had fun writing that paragraph. :-)

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daave
I got so confused by this retrieval pricing scheme I decided to make a
spreadsheet to calculate the bill for various usage patterns, feel free to
fork it and edit the numbers/scenarios:

[https://docs.google.com/spreadsheet/ccc?key=0AnYE99fIo31idFd...](https://docs.google.com/spreadsheet/ccc?key=0AnYE99fIo31idFdudy1QMGRJUFpDWVJ4VzFaTUJ5Ync)

In short, the scheme very heavily penalises doing a large restore from backup,
but it's quite cheap if you just spread your restores gracefully across the
month.. which makes a lot of sense if they're using tape drives.

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cperciva
I find that an easier way to think about the the retrieval pricing is
"bandwidth overage times peakiness", where "bandwidth overage" is the amount
of data retrieved in the day minus [5% of data stored]/[length of month], and
"peakiness" is the proportion of the day's data which was retrieved in the
peak hour (somewhere between 1/24 and 1).

~~~
daave
Right.. and it's that peakiness factor that really kills you.

PS: If you were 'anonymous user 21' looking at the spreadsheet around 20 mins
ago, sorry I was screwing with things, making all the bills look like $0, it's
fixed again now.

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jmount
The hidden strictnesses (triggering per-day costs even when you are below what
is described as a per-month allowance) make me think of "glacier pricing"
where glacier is a common noun instead of a proper noun. I.e. 90% of the costs
being hidden below the water.

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ufo
Those are icebergs. Glaciers are inland ;)

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tedunangst
Is this actually a case for tarsnap support? If you aggregate lots of people's
data but only some of them access it, it's cheaper.

The common use I see for glacier is store something, but retrieve all of it
only once per year. Everybody storing their own data pays in that case. But if
you get 1/(5%) == 20 people to pool equal amounts, every one of them gets a
free retrieval every month.

~~~
cperciva
Yes, in the common case there's an arbitrage potential here -- but as the
story of Alice and Bob illustrates, it's possible for the arbitrage to
backfire.

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arasmussen
User A stores 1 TB and can get out 1.7 GB for free per day. User B stores 100
GB and can get out .17 GB for free per day.

It doesn't make sense to me why this free read amount should be higher for
User A than it is for User B, since Amazon is such a "pay for what you use"
service. If they both read the exact same amount (read 1 GB), User A gets it
for free and User B pays.

I understand that this is paid for from your monthly fee from how much you're
storing, but then (again) this isn't "pay for what you use".

