Hello all, I've been reading these forums for a long time, having gone from Windows over to Mac last year, and have found them to be really valuable (as well as entertaining!). I have searched the forums but not found the answer, but apologies if it is there somewhere. Here is what I have: I have an iMac, MBP and MBA - a Time Capsule handles the backup for all of them. I have an external USB enclosure connected to my iMac (which I leave on all the time) which holds two hard disks. I have my iTunes library mirrored over these two disks using RAID 1 which I set up with Disk Utility. Because this is attached by USB, Time Machine includes the drive in backups. I put the iTunes library on the external drive so as not to clog up the drive on the iMac which I use for home photo editing, video editing etc. and to give the library breathing room to grow - its about 600gb at the moment. Additionally I have a ReadyNAS Duo - originally bought for backing up my old Windows desktop. I tried putting my iTunes library on this but as Time Capsule/Time Machine doesn't back up network attached disks, I now plan on using this as a periodic mirror of the Time Capsule disk to keep off-site. I also have a few SATA disks of varying sizes from 500gb to 1gb which I'd like to put to good use. I have it set up this way as it kinda grew organically, and the NAS and extra drives are left over from pre-Mac days. If there is a much more sensible way to do things, I'm all ears!! If it helps to know, I also have an Apple TV and airport express feeding music to a Zeppelin - hence why I leave the iMac on all the time. Here is what I want to achieve: The external USB enclosure is a few years old and has had its fan replaced twice. I am still a little uncomfortable about whether it is offering suitable ventilation for the drives in it. So I would like to replace this with something that gives me extra space and is quicker. Ideally I would like to connect to the iMac with Firewire to make use of the increased speed, and I would like to make use of a couple of my spare SATA disks. I would then look at freeing up some space on the iMac by moving photo libraries and video files over. So I've looked at a few 4-bay external drive enclosures, and found that they are pretty expensive for what they are (£200+ for one which supports firewire). Drobo do a unit I think, but the reviews were mixed and I don't need any of the bells and whistles it offers. I also considered getting a PC case and putting all the drives in there, but I don't know how to connect this to the iMac through USB or preferably Firewire, or what controllers I would need to put in the PC case as the interface. I know this would probably cost about the same but if I bought a big case I could fit more disks inside. I have built PCs from scratch before so am reasonably confident about being able to fit this out. Before it's rightly pointed out, I know that if my iTunes library grows so big as to actually use all the extra space, I will have outgrown the capacity on the Time Capsule! Problem for another day methinks. As the £ sign above will have indicated, I'm in the UK. So, if anyone has had a similar conundrum and managed to solve it, I'd be really interested to hear how; and if anyone can offer advice, I'd really appreciate hearing it. Thanks in advance.