Question: I have a Dell PowerEdge R300 with a Dell SAS 6/iR Internal Controller RAID PCIe and two 250GB SATA HDDs in RAID1 configuration. One of the HDDs has died so I want to swap it out for another. At the same time I'd like to increase storage to 500 or 750GB. Can I just plug in say a 500GB HDD, wait for it to sync, then swap out the other old drive for another 500GB drive? 

Or, how do I find out if this is possible - i.e. what's the terminology for this if I want to search around in manuals etc?

Also, I'm assuming that I can get any 3.5" SATA (or SATA II) drive and it'll work and be hot-pluggable. Is this correct?

many thanks!

Answer: 
The feature term you are looking for is *"Online Capacity Extension"*. Dell SAS iR controllers [do not support it](http://lists.us.dell.com/pipermail/linux-poweredge/2011-February/044279.html), the [PERC and CERC controllers do](http://support.dell.com/support/edocs/storage/RAID/PERC6/en/UG/HTML/chapterd.htm). So with the iR controller, you would have to insert your two new disks, create a new large container and copy the data over from the old one.

> 
> Also, I'm assuming that I can get any 3.5" SATA (or SATA II) drive and it'll work and be hot-pluggable. Is this correct?
> 
> 
> 

Basically yes, although controller-specific limitations may apply (like a 2TB volume limit). You should make sure that you use "24/7" rated drives - the appropriate models also usually come with larger caches, higher MTBF ratings and a longer manufacturer warranty (3 to 5 years).
1. When you replace disks one by one and sync, you'll end up with a new RADI1 array, with the size of 250Gb, and the rest of the space on the disks will be unused, but available, for creating another raid array on the rest of the space available.
If you want the entire space in a single radi1, you need to backup, test backup, create a new large array, and restore the system to the new array.
2. Only Dell HDDs will be supported in a Dell server. They are the onyl drives that were tested to work in this machine, and if something goes wrong, support will ask you tyo remove any non-Dell kit before proceeding with testing your machine for errors. Obviously, without drives, it will not be a simple task to reproduce most of the issues that can occur.