If you didn't realize by now, storage is all about the price you pay for what you get. Well, I suppose that's true for just about anything, but especially for storage. It sounded profound when I said it in my head earlier. Essentially, there are several things that I think about when looking at storage options in any case, and even when buying something for my home:
- Capacity
- How much usable storage do I need, and how much will a product give me?
- Speed
- This is less important for a home system, but still important. What are the drive interfaces? What is the host interface?
- Redundancy
- Yes, even with home systems, you need redundancy. It might not ruin my business if I have a multi-drive failure at home, but it sure will ruin my month.
- Expandibility
- Think about your needs on down the road, is what you buy going to last you?
NAS
At the bottom end of home storage, there are devices like the LaCie Ethernet Disk and the Buffalo TeraStation. I generally don't care for any of these devices because they're usually very Windows-centric and run proprietary OSs. What happens if I want to connect my Ethernet Disk to my LDAP system, or use it in a different way than the manufacturer intended? Too bad. Plus, for any sort of RAID5-level redundancy, you're going to be paying a bit of money.
Let's instead look at the bottom end of enterprise storage, where we have a few NAS devices that work quite nicely. The two that come to mind off-hand are the Dell PowerVault 715N and the Iomega NAS p4XX. Both of these are pretty similar, 4x PATA drives in the front, 2 10/100 NICs, standard PC guts. Are the drives very big? No, but they're easily upgradable. Is the OS very good? No, but it's just a PC, so load whatever you want.
This brings us to another point, hardware RAID or software RAID? Years ago, hardware RAID had it's place. Systems were too slow to keep up with all of the RAID calculations, so a dedicated hardware RAID controller took care of that by offloading the RAID calculations from your CPU. They also added large amounts of cache to speed up transactions. Now, for small setups like what we're talking, hardware RAID would be a waste of time and money. If your controller fails in some way, how will you get your data back? (Hint: You won't. It's gone. Bye-Bye.) Software RAID transcends hardware, so just pull those drives and mount them in another system.
But what OS? In a previous article, I discussed my decision making process for what to run on my Iomega unit. ZFS is certainly the best thing going, if you can get it to run. Barring that, FreeNAS or OpenFiler would make nice alternatives, or just using FreeBSD with vinum, which I did for some time as well. Linux and EVMS would also work nicely.
SAN
Oh, but you want more, huh? You say, "Zach, this just isn't enough, I crave real enterprise hardware!" Well, the best game in town are Fibre drives. Yes, that's right, Fibre. Think about it, who wants a Fibre drive? Who do you know that needs a Fibre drive? More importantly, who in their right mind would buy a Fibre drive and array off of eBay? We would, that's who.
It won't cost you much to get started with Fibre. First you'll need a cabinet. Being a Sun guy myself, I like the A5200 or the T3/T3+. They're available pretty cheaply on eBay, I've seen A5200s for around $50. You need an HBA, this is the part that connects your computer to your cabinet. A qlogic 2100F is about $10 on eBay. Now you need drives. A 73.4gb drive sells on eBay for about $50. Oh, and don't forget, you don't just have a big array now, you have a SAN. The A5200 will accept 2 HBAs, and you can plug them into a Fibre switch and connect even more systems. Need a little extra space on your server? No problem, carve out a LUN on the SAN and map it to the server in question. Want to learn about HA Clustering and Failover? Again, not a problem. Map a LUN to 2 hosts, install Sun Cluster, and go to town. Maybe you just want to run filesystem performance tests? You have a wad of drives at your disposal. And expandable? Hey, you've set everything up now, just buy another cabinet.
