So, I'm collecting parts for a new server (web/db/mail/NAS). Among other things, I'm looking to get two 2.5" drives to be mirrored (ZFS mirroring specifically, comparable to RAID1) for the system to be installed on - the data will be on a ZRAID2 (like RAID6) array of 3.5" WD RED disks that I have already started purchasing.

Now, I know WD do have 2.5" drives in the RED series, but while the smallest at 750 GB would more than satisfy the storage I need (as mentioned, it's really only for the base system driving the hardware), I do wonder if there are other options regarding 2.5" drives built for RAID and continuous usage (SSD and HDD are both applicable). Seagate have (or had?) their NAS series, but that's only 3.5" drives as far as I can figure out.

Beyond that I really only require a PSU before I can start building the thing, but that's a later concern.

Aren't you really just looking for a NAS case with a RAID controller? It sounds like you should be able to use almost any off-the-shelf hardware like this, unless you're specifically wanting to handle the redundancy outside the case.

[url= But, assuming I'm not missing the point entirely, you might be best served with a thing like that - it seems to allow you to RAID mirror a pair of drives, while keeping a striped or JBOD volume separately for storage and more NAS-sy behaviour. Heh. NAS-sy. ][/url]

EDIT: Oh, duh, unless you just meant what disks to buy, then there's really only one option, the Western Digital. But not the RED silliness. No, you want the 10k RPM drives, entirely because they're called VelociRAPTOR. VelociRAPTOR drives. Say no more.

SECOND EDIT: So, I'm not really a server wonk, so if someone shows up who has actually put the hours in and says my advice is crap, they're probably right. But I have got a fair bit of experience with RAID 1 in call managers, because I'm a network nerd, and I'll say this - you generally don't need to pay the 150%-200% markup for a "RAID drive" in a low-priority setting. Most of the drives in the CM servers I've managed are regular desktop drives. If you're using a hardware RAID controller (and you should be, because software RAID is a real thing, and should not be a real thing) then you're just hitting your hard drives normally. If you're not providing a service to a customer where momentary downtime is a huge problem, then you can afford the somewhat lower MTBF that results in one or two short hiccups over the drive's lifetime, while you fail over to single drive and rebuild the RAID.

Is this for personal use? As long as you store all db and mail data on the data raid, I wouldn't bother with raid on the system drive, unless it really is critical that you don't have any downtime. The system drive won't be getting that much activity in such a setup, and there shouldn't be anything on it which you absolutely need to keep.

Yeah, this is all wrong. Thought you were joking with the VelociRAPTORs. ZFS is quite a bit different. Software RAID has come a long way.

Also, no such thing as ZRAID2. It's RAIDZN (RAIDZ2) and N-way mirrors.

Here's a better intro link to ZFS.

Out of curiosity what OS is this system going to be based on?

Of course I was joking about the velociraptors. >.> That's why it was its own edit >:(

Like everyone who has ever, for the last decade, told me you can't use normal drives for RAID, you neglect to show any sort of reason. You got anything other than once every ten or twelve months you'll lose a drive and have to rebuild? Because nobody who claims to do servers ever gives evidence or even anecdotes, and after a few thousand hours of seeing normal drives run RAID in production, you start to wonder where the downside actually is. All I know is error recovery takes longer, but you don't see a lot of that with good hardware anyway.

Course, all of that is irrelevant if OP isn't interested in hardware RAID, innit?

Guess my response was a bit broad. I wasn't addressing this bit. Ten or twelve months and a drive? Rather depends on the load, the controller, the firmware and the OS drivers. Plenty of horror stories out there. You have a well behaved controller and a simple mirror? As you know you can often make out just fine. Actually, not completely. TLER is beneficial even for software RAID. If you have the redundancy it's better to give up, pull the data from another drive, and rewrite the data on the initial drive.

Yeah, of course I messed up where in the name the Z is (was a little while since I read up and decided on what to use), RAIDZ 2 is what that should be, and a simple 2-drive mirror for the OS. On-metal will be FreeBSD, VMs will likely be a mix between FreeBSD and GNU/Linux (don't currently know which distribution/s, though I run Arch on the desktop so that's as likely a choice as any) and maybe Windows and whatever else I'd like to tinker with, at least if "whatever else" runs in bhyve.

EDIT: Also, yeah, it's for my personal use, replacing, and expanding on, a Mac Mini G4 running OS X 10.5 Server that's been in use for way too long (and is a bitch to administrate).

EDIT2: And the idea of running the OS drive mirrored is mostly due to hopefully not requiring to reinstall the OS and set it up again in the same way should the OS drive fail (ie. minimising work rather than downtime), minimising downtime rather than work is mostly a bonus (having my main mail address be accessible is of course nice).