I have been watching a few Storage Spaces threads on Microsoft’s support forums with interest. Storage Spaces is a new way to manage disk storage in Windows 8 and Server 2012. It lets you create a pool from two or more drives, create virtual drives on them with an option for RAID-like resilience, and add or remove physical drives as needed when drives fail or more storage is needed.

A great feature, and particularly since it comes from the server team you would expect it to be solid. Nobody can afford to use storage that is unreliable.

Look at this thread though, based on Windows 8 Enterprise Evaluation which should be the RTM code:

I had three empty discs which I used for it: 320 GB, 1 TB, 2 TB. The manager told me that the maximum capacity for this setup would be ~2 TB.

I then proceeded to fill the space up, resulting in a horrible write speed of ~20 MB/sec. Okay, that can be accepted, it is a software solution, after all.

Here’s the kicker, though: Upon reaching ~0.9 TB, the storage space vanished! Yes, vanished.

After invoking the Storage Space Manager, I discovered that the space was deemed “full” and that I was to add another disc. I also took a look at the volumes itself. Hmmh. The 320 GB disc was 100% filled, the 1 TB was at 32% and the 2 TB at 16%. And what are 32% of 1 TB and 16% of 2 TB? Why, 320 GB!

So, instead of creating a Parity storage space, it simply downsized every hard disc to the lowest denominator, i.e. 320 GB.

Which means that there are two massive problems here:

1. It’s lying about the remaining capacity (which is confusing in itself: The manager talks about the storage space having a 2 TB capacity, but directly above it talks about a 3.01 pool capacity?)
2. It also gives no warning when the real capacity is reached and the pool is deemed “full”. It simply takes the pool offline (instead of, say, reverting to a “read-only” mode with a warning) and you have to bring it online manually. Not fun.

and later, from another user:

Today while I copied data over to it, it once again reached “full” status and turned itself “offline” – but this time it won’t come back “online” – it changes right back to “offline” as soon as I try to bring it online…  So essentially I cannot access any of the data on the drive anymore.

or this (which likely refers to the RP) – the article to which it comments is worth a read too.

I’ve run into a major problem with storage spaces. My storage space is full. Having a full storage space puts it into an error state, and it goes offline. You can click “Bring online” but it immediately goes offline again.

So, I can’t free space on it, because I can’t get it online to delete stuff. And, more importantly, I can’t get anything off of it because it won’t stay online.

It seems my only option is to add three drives, as I had it set to parity. The only problem? I don’t have three more drives to add.

Even bugs in in the RP worry me. Storage is so fundamental that I would expect a feature like this to be 100% solid early in the release cycle, or pulled.

Update: It now seems to me that Storage Spaces is working as designed (phew!) though it is understandable that users are confused. See the new post here.