Question

I think we have gone slightly wrong on the way we have used Azure storage in a SAAS system. We created a storage account per client (Securtiy was prime consideration) and containers per system area e.g. Vehicle, Work etc

Having done further reading it seems a suggestion would be that we should have used one account for all clients. Each client should have a container (so we can programmatically create it) which we then secure. Then files should just be structured using “virtual” folder structure e.g. Container called “Client A”. Then Files for the Jobs (in Work area of system) stored like Work/Jobs/{entity id}/blah.pdf. Does this sound sensible?

If so we now have about 10 accounts that we need to restructure. Are there any tools that will let us easily copy one accounts contents to another containers account? I appreciate we probably can’t move the files between accounts (as we set them up ages ago so can’t use native copy function) so I guess some sort of copy. There are GB of files across all the accounts.

Answer 1

It may not be such a bad idea to keep different storage accounts per client. The benefits of doing that (to me) are:

1. Better security as mentioned by you.
2. You’ll be able to achieve better throughput / client as each client will have their own storage account. If you keep one storage account for all clients, and if one client starts hitting that account badly other clients will be impacted.
3. Better scalability. Each storage account can hold up to 200 TB of data. So if you keep just one storage account and assuming each client consumes 100 GB of data, you’ll be able to accommodate only 2000 clients (I hope my math is right :)). With individual storage accounts, you won’t be restricted in that sense.

There’re some downsides as well. Some of them are:

1. Management would be a nightmare. Imagining you have 2000 customers then you would end up managing 2000 storage accounts.
2. You may be limited by Windows Azure. Currently by default you get about 10 or 20 storage accounts per subscription and you would need to contact support to manually up that limit. They can do that for you but I would imagine you would want this to be a self-service model where you would be able to create as many storage accounts as you want without contacting support.

Now coming to your question about tooling, you could possibly write something on your own which makes use of Copy Blob functionality. This functionality allows you to copy blob data across storage accounts asynchronously. Basically this is what you would do is:

1. First create a blob container for each client in the target storage account.
2. Enumerate all blob containers in source storage account.
3. For each blob container in source storage account, enumerate the blobs.
4. Copy each blob asynchronously to target storage account in the client’s blob container.

If you’re a PowerShell fan, you can look into Cerebrata’s Azure Management Cmdlets (http://www.cerebrata.com/Products/AzureManagementCmdlets) as well which wraps this functionality. I could have recommended Cerebrata’s Azure Management Studio as well but I haven’t tried this functionality just yet there [Disclosure: I’m one of the devs on Cerebrata team].

Hope this helps.