Internal vs. External RAID

So a recent thread in the Creative Cow Final Cut Pro forum about Internal vs. External RAID's got me thinking more about the subject. I'm a firm believer in external RAID's and really don't have any desire to install 3 or 4 drives inside my Mac Pro tower.

Let's think about this. Companies like LaCie, Ciprico, Medéa, CalDigit, Facilis and others spend a lot of time in research and development to produce storage solutions that are not only fast, but reliable. Every board, every drive, every switch, everything about that storage solution has been drawn up, assembled and tested by engineers who know a heckuva lot more than me about the inner workings of computer storage.

The hard drive units themselves are rigorously tested and "beat up" to figure out which manufacturer and model should be installed in a particular RAID unit. Drive reliability is different among manufacturers and even among individual models of the same manufacturer. Company X may have a killer 500GB model but the 750GB model may have issues. RAID companies will discover this issue much faster than I ever will and adjust their products accordingly.

RAID companies that I've dealt with have had very good tech support teams both for generaly questions and in the event of a failure. This is invaluable because when something goes wrong and a deadline is looming, the last thing I want to do is become a hardware engineer and try to figure out exactly where something might be wrong. I have enough trouble just keeping up with all the formats and software we run, I really don't care to become a computer engineer too.

Expansion is so much easier with an external RAID than internal. I mean, what do you do if you have maxed out your internal RAID and now you need another 2TB of storage? I guess you're going to connect an external RAID device? So now you're working with internal AND external media storage, at the same time? That doesn't sound like a very stable solution in my book. Start external, expand external. Keep everything coming down one or two pipes from the outside.

Speed is very limiting when it comes to internal RAID. Four drives striped together are going to be slower than say a 10 drive Ciprico Fibre Array, or maybe two arrays striped together. Heck stripe four of the new CalDigit 4:4:4 arrays together and you're pushing upwards of 900MB/s. You're not going to touch that with and internal RAID and you're certainly not going to stripe and internal AND external RAID together to gain more speed.

Zero protection is had by current internal RAID's as RAID 0 and 1 are the only supported formats right now. With External RAID's you have a multitude of protection options which gives you real control over speed vs. protection. Granted, right now I run an external SATA Array in RAID 0, but I also run another external backup device. But that will change in the next few months and we migrate potentially back to Fibre Channel.

I figured I'd ask an engineer I know about this debate and he said external is always the preferred way to go when working with high volume media storage. It's generally faster, more stable and a much more proven technology.

There you go, my reasoning for working with and recommending external RAID storage. You're free to do what you want, but this is where I stand on all this.

Well, surfing around the net the other day I found Peter Wiggins' blog and funny how the same thread I referred to above, also got him to post his thoughts on the subject of Internal vs. External RAID's. It appears that I got under his skin a little. An excerpt:

Now, what really got my goat was the fact that a well known forum host was saying that he didn't recommend internal RAIDs.

Now Peter is a fantastic guy and really knows his stuff and I just wanted to say 'Peter, I've got your goat and I've taken really good care of it, but I think he wants to go home. So meet me in Vegas and I'll hand him back to you.'

That's the fun part about our business, there are so many varied opinions and if we all agreed to everything all the time, how boring would that be? Here's Peter's entry if you want to read his easy to follow instructions on installing an internal RAID.

http://peterwiggins.com/content/view/12/33/

As long as you're stuck with the Mac Pro enclosure, I agree. I run a Windows workstation in a Thermaltake Stacker case with 8 drives in RAID 5, on an Areca 1120 PCI-X hardware RAID adapter. Easily runs over 250 MB/s throughout 85% of the drive capacity, and no heat problems.  The most cost-effective high-performance RAID solution I could come up with 18 months ago. And since it's hardware RAID there's hardly any CPU load. 

The main problem with internal Raid arrays is, from our standpoint, resource allocation.  In order to have an efficient Raid 5 (for example) setup, you really need to have at least 5 drives in the array.  That's too much of a load for internal resources (space, heat, power) in most cases.

We much prefer external SATA arrays interfaced to the computer thru dual-channel U320 SCSI (or 4 Gb Fibre).  A little more expensive than straight SATA, but so much more versatile and more reliable.  One of our HD systems, for example, regularly uses 16 SATA drives (RAID5) to provide dual stream, uncompressed 1080i along with hot swap, hot spare(s), and full data security (no backup needed).

It's pretty much a no-brainer if multi-terabyte capacity is required.