Thank you! In the interests of full transparency, the blog post was a collaborative affair and was proof read and edited for clarity by several people at Backblaze.
> discussion about why it doesn't matter
One of the philosophies Backblaze uses is to build a reliable component out of several inexpensive and unrelated components. So combine 20 cheap drives into a ultra reliable vault. We have two or three inexpensive network connections into each datacenter instead of buying one REALLY expensive connection for 8x the price. Etc.
Personally, I recommend customers do the same. Instead of storing two copies of your data in two regions in Amazon for 2x the price, store your data in one region of Amazon and put one copy in Backblaze B2 for 1.25x the price. We believe this will result in higher availability and higher durability that two copies in Amazon because Amazon S3 and Backblaze B2 don't share datacenters in common (that we know of), don't share network links, don't share the software stack, etc. For bonus points, use different credit cards to pay for each, and have different IT people's credentials (alert email address) on each. That way if one IT person leaves your company and you don't get an alert that the credit card has expired, hopefully your other copy will be Ok.
> BB and S3 both have eleven 9 durability, how much does using both increase this?
Putting your data in either Backblaze B2 or Amazon S3 suffer from other failure modes outside of the durability of the raw system. For example, let's say your IT person is poking around in their Amazon S3 account and accidentally clicks the "delete" button and all your data is gone? Or what if your credit card has a transaction declined, and your IT guy has left your company or the emails from Amazon are being put in the "Spam" folder of your email program. Or maybe a malicious Amazon employee writes a program to delete all the data in Amazon S3 from all customers? What if one of your employees is really disgruntled and logs into your Amazon S3 account and just to spite you deletes all your data?
In every one of these situations, if you have a copy in Backblaze B2 and also another copy in Amazon S3, you can recover your data from the other vendor.
I recommend using a separate credit card to pay for your Amazon S3 account and your Backblaze B2 account. They should expire a year apart. And don't give the logins to both systems to one disgruntled employee in your organization. Only give that disgruntled employee access to one or the other.
Depends what you are modeling. The probabilities of random disk failures, are probably independent.
However, there are risks that are not necessarily independent such as the US Government ordering these two services to delete your data, or, as the article mentions, an armed conflict destroying data centers.
> well written and refreshingly transparent
Thank you! In the interests of full transparency, the blog post was a collaborative affair and was proof read and edited for clarity by several people at Backblaze.
> discussion about why it doesn't matter
One of the philosophies Backblaze uses is to build a reliable component out of several inexpensive and unrelated components. So combine 20 cheap drives into a ultra reliable vault. We have two or three inexpensive network connections into each datacenter instead of buying one REALLY expensive connection for 8x the price. Etc.
Personally, I recommend customers do the same. Instead of storing two copies of your data in two regions in Amazon for 2x the price, store your data in one region of Amazon and put one copy in Backblaze B2 for 1.25x the price. We believe this will result in higher availability and higher durability that two copies in Amazon because Amazon S3 and Backblaze B2 don't share datacenters in common (that we know of), don't share network links, don't share the software stack, etc. For bonus points, use different credit cards to pay for each, and have different IT people's credentials (alert email address) on each. That way if one IT person leaves your company and you don't get an alert that the credit card has expired, hopefully your other copy will be Ok.