Dell Compellent – Preallocating storage

In my first post on the Dell Compellent, I’d mentioned that it was possible to preallocate storage on the array, even though it was thin by default. I can’t really think of a reason why you’d want to do this on this particular array, but here’s how to do it.

Firstly, create the volume but don’t map it to anything. Then wait a little while. I can’t remember how long, but it’s a little while. Then right-click on the volume and the option to “Preallocate Storage” will be there.


You will be warned that you’ve basically turned your back on years of hard work by the Compellent developers. Think about that.


When it says it will take several minutes, it’s not lying.


It will probably take a lot longer than several minutes, particularly if you’re making a 20TB volume, like I am.


In fact, the array will get a bit concerned about how long it’s taking as well.


Five hours later, and about 7.5TB has been preallocated.


Here’s a picture of it when it’s finished. Note the lack of space.


You’ll also notice that the storage is in conservation mode now, basically because there’s not a lot of space left to work with.


You can right-click on these alerts to “Clear Emergency”. Note, however, that you need to have actually cleared the emergency (made space, for example), before you can, er, clear the emergency.


Note also that it takes a little while to delete a 20TB volume.



And there you have it. It is possible, and there might even be a reason for doing it. But then you might just have bought the wrong array for the job.