Decision 7: Which Type of Drive?
Hard drives have their own complexity, but the choices offered may make a difference to you. Let’s break this down.
Capacity: first, you need to decide how big a hard drive you need. With external storage, this isn’t a life or death decision because you can always add more drives later (actually that’s true with internal storage too, but you still have to consider whether you want music data and the OS on the same drive).
We’ll get into music storage formats later, but for now you should know that these formats affect how much capacity you need. To be conservative, if we assume everything will be stored as uncompessed (e.g. .wav) files and if we assume the average CD has 400MB of data on it, you need about 500GB per 1000 CDs (or 10,000 songs). That amount will give you a little extra capacity. 1000 CDs is a lot, but not uncommon for avid music collectors.
I was surprised when I counted the CDs in the lab and found the count at 1600. Not all of those are keepers, but then again I’d like some headroom. Since 1TB is not much more expensive than 500GB, we’ll use that as a base capacity for the system we’re building.
Interface: you’ll need to determine which interface to use for the hard drive. On a Mac Mini (or iMac) this means choosing between Firewire and USB. USB is the slightly less expensive way to go. Firewire is slightly higher performance (Firewire 800 has higher transfer rates than USB 2.0 and this is rendered even more relevant in practice because Firewire is not CPU dependent as USB is).
You will want to consider at this point which DAC interface you plan to use. Firewire is also a better DAC port to use for the reasons stated above, but there are far fewer Firewire DACs than USB DACs. There is debate about this, but my feeling at this point is that I would ideally (cost no object) get the DAC interface right and live with the lesser drive interface (one could put DAC and drive on the same interface too, but that seems risky).
That said, I plan to use the Firewire port for the hard drive on our project server. Why? The key reason is that we will be testing a lot of USB DACs. I also think that a focus on USB parallels the current focus of users on USB DACs.
Backup Scheme: there are a lot of choices here. First, given the effort to rip a big library, combined with the cost of losing downloads, most users will want a back-up scheme. In other words, you could have the backup scheme called “none” but I can’t recommend it.
One basic backup approach is to have a RAID drive as your external drive. This will be RAID level 1, which means you will have two drives in one cabinet and each drive will automatically be written to identically mirror the other. If one drive fails, you have the second drive. To me that is comforting, and RAID raises the price of 1Tb of capacity by only about $100 so the cost isn’t horrendous (but it’s your money, so don’t let me spend it). Note: remember that you’ll have to buy a 2TB RAID drive to get 1TB of effective capacity.
Drives can fail, so you might want to backup your music to a NAS (Network Attached Storage) drive. This is just another external disc with an interface to your network router rather than directly attached to your PC/Mac. Even RAID drives can fail, so NAS backup can be a good idea either way.
Quietness: if your external storage is going to be in a listening area, you will want a drive that is quiet. This can be hard to assess, but there are fan-less drives. You could also address this by putting the server in an enclosure.
Speed: Presumably lower seek times and faster transfer rates are advantageous. Since the transfer rate of a typical hard drive exceeds the data rate needed for music by a factor of 50-100, at this stage I’m willing to assume it is a minor factor. Seek time could matter and we may get to roughly test this if we can use an SSD (solid-state drive) in another project. Again, I’m not sure if the small seek time differences among traditional hard drives matter, nor do I know if quoted specs are a reliable indicator of actual speed.
In the end, given these criteria, I chose a LaCie 2Big Quadra 2TB RAID drive. This gives us 1TB effective capacity. It has Firewire 800 ports (as well as USB, eSATA and Firewire 400). The LaCie has hot-swappable drives which seems convenient. And it is partially passively cooled which I hope makes it quiet enough to have in the listening space.
The LaCie costs $295 (street), so to this point I’ve spent $1143 of my allotment (we could add $100 if you need a monitor and subtract the $58 I spent on needlessly fancy hard drive and processor, for a total of $1185 all-in).