Cloud Backup

[Shachar Shemesh]

On 17/05/13 11:43, Oleg Goldshmidt wrote:
> Shachar Shemesh <shachar at shemesh.biz> writes:
>
>> On 17/05/13 10:13, Ghiora Drori wrote:
>>     
>>     https://aws.amazon.com/glacier/#highlights
>>     Quote: "Amazon Glacier is designed to provide average annual
>>     durability of 99.999999999% " 
>>     
>>     If this is not good enough for you too bad.
>>     
>>     
>> When you see someone, anyone, saying such a thing, run. As fast and as
>> far as you can.
>>
>> This level of assurance is called "nine nines"(henceforth 9*9). It
>> amounts to one thousandth of a second of downtime a year.
> I think you are misreading the claim, Shachar. It is not about
> availablity, it is about "durability". I read it as a measure of the
> probability that your data will not be lost before a year passes.
You are right that this is not about availability. The previous response
was my fuse jumping because of the pure ludiciority of people claiming
9*9 availability. After reading the actual text, however, it is not
clear what it is about.

It is possible that this means that they will lose (on average) ten bits
per Terabyte per year. If that is the case, honestly, this does not
sound very good. Assuming they have several exabytes of customers data,
this means that they have several actual cases of customer data lose all
the time. Not a particularly good track record.

Or, and this is the more likely scenario, they are talking out of their
asses, and put the number in because it sounds impressive.

Omer Zak wrote:
> IMO, the quote does not promise a nine nines assurance.
> It only says that Amazon Glacier WAS DESIGNED to provide this kind of
> assurance.
See my previous comment for why this is equally ludicrous.

Shachar
>
> Disclaimer: I have never used the service and th above is my "common
> sense and reading comprehension" take on what is written in the above
> website.
>

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