is it secure?
In the era of API keys and security compromises it seems a lot safer if you actually want to retain that data to store at least a copy of it OFFLINE, where something like a compromised API key(or admin website login) can't be used to magically wipe out all your data. Most people don't realize this for some reason or another.
Restoring from offline tape(or disk) would often require some human intervention to get the right tape(s) into the tape drive before they could be messed with.
In just doing a brief web search I see there is a WORM storage provider for Azure but the big catch from what I read on their blog is you have to give them all of your data and access it through their interfaces only, they admit if you had direct access to the azure controls you could bypass all of their controls and wipe out the data. Perhaps there are other solutions I haven't looked too closely but in my own conversations with folks over the years there doesn't appear to be any awareness of this critical shortfall of most cloud storage solutions for archiving data. WORM isn't quite the same thing as offline storage but it's as close of a term as I could come up with to search by.
Some enterprise storage arrays have similar built in retention stuff, though I've never used any of it. I remember when 3PAR came out with VirtualLock, where you can lock volumes and not even storage admins can bypass the lock preventing you from removing the volume(in most(all?) cases I assume it would be a read only snapshot so you couldn't modify it either). I suspect support could not either, though they could wipe the data by wiping the underlying drives.
Also don't forget about the bandwidth required to retrieve the data if it is any significant volume. Perhaps there is a cloud->tape/disk service as well which would accelerate that.
I see some WORM like storage on amazon cloud but the doc implies it is easily overridden if you have admin access to adjust the policies.