RAID 0 performance gains?

Question

I'm building a new computer over the summer. I'm fairly competent in computer hardware, and am thus building the computer from scratch. I have everything planned out, but I was wondering about RAID. I asked which RAID I should use earlier, but now that it's pretty clear that RAID 1 isn't really that great, I think I'll go with cloud-backup instead of disk-redundancy. However, I still face a choice: use two 1 TB drives as two 1 TB drives, or combine them into a RAID 0 striped array. Is there any performance gain at all? I know that if one drive dies, everything is gone, so is the performance gain worth it? I'm building a pretty advanced computer, with SLI video cards and a fast CPU, so I'm thinking RAID 0 would give me some good hard drive performance. From your experience, is RAID 0 viable?

Solution 1

Hardware-RAID-0 is always faster than a single drive because you can step the reads and writes across the two drives simultaneously. Downside is that if either drive fails, you lose data on both disks. So if your backups are good, and you are willing to take the risk of a slightly higher risk of data loss, go for it.

Software-RAID-0 can provide improvements, but in my opinion not enough to justify the increased risk of data loss. Also, you almost can almost never boot from a software-RAID-0 partition.

Wasn't there an article recently that had an obscene number of TB drives in a stripe to see how the performance compared?

Solution 2

I'd buy an SSD and put my OS and programs on that, and use the disks for data storage.

Solution 3

Don't do this. Instead of buying one of those TB hard drives, buy a western digital raptor or velociraptor drive. It's small, yes, but you don't need to put THAT much content on your main system drive.

What you get are latency and transfer speeds that far exceed what two large TB drives will ever be capable of. Even though the throughput from raid is pretty high, you still have to have one of your two drives find the start of a file before it can begin playback, meaning that for many smaller files, or when you're accessing lots of different files, as during startup, your raid array is not speeding things up substantially. Furthermore, it might even be degrading performance, depending on your read/write problem.

Go with a fast 10k rpm drive as your system drive for the things that need to be fast, and use a big drive for media storage. They're different tasks, use the appropriate hardware for each.

Solution 4

Raid 0 with two drives is not going to show much improvement in the way of performance. Sure there will be some, your are splitting your writes between two spindles, but not enough for it to really make a difference.

Where raid 0 really shines is when you are string many drives together, say 15. Now when you split your writes across that many drives you will surely see an improvement in your disk io and latency.

If your machine supports a hardware raid and you are looking for some performance/redundancy improvement, why not go to three drives (or four) and setup a raid 5 array. Sure there is a slight performance hit during writes, but I am willing to bet your computer usage will be mostly reads anyhow.

I just finished building a new workstation (gaming + development) for myself just two weeks ago, I decided to go with an 80GB SSD on the boot drive and three 500GB HDD's, in RAID 5 configuration, for data. I swear to you, once you go SSD, you will never go back.

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Comments

[NickAldwin]

I have hardware RAID, so it sounds like RAID 0 would be a good choice. Thanks!

[NickAldwin]

Not even if it was backed up?

[NickAldwin]

Unfortunately, some of the programs I regularly use both a) put lots (think GBs) of data in the program files folder b) act funny if they aren't installed to C: meaning that I have to use a large drive as my system drive. Believe me, I prefer the other arrangement and had it on two of my other systems, but these programs tend to be annoying. What size would you recommend for a OS-only drive, if I decided to go that way?

[NickAldwin]

And is the 10k rpm a huge improvement over 7200? or just marginal? I'm not sure I'm ready to spend $50 more for 800GB less.

[Paul McMillan]

Look at the file seek times. You're looking at half or less from the huge storage drives. For tasks like booting your system, running games, anything that involves loading multiple files, the high performance single drives make a huge difference. Obviously, for the programs that put lots of data on the drive, you use a media drive. Are you absolutely certain that the programs you use MUST be on the C drive? Also, windows xp and above include support for mounting one drive within a folder on another, so if you don't HAVE to be in the ROOT of the drive, it can look like a big drive.

[Paul McMillan]

I've run my system drive on the first generation 75GB raptor for a long time now. 75GB is enough for me, but your needs may vary. 250 is certainly plenty.

[Jauder Ho]

It all depends on your tolerance for data loss. I have some directories backed up to NAS which I am okay with losing the local copy. In case of data loss, I'm fine with just copying things back over. YMMV.

[EMP]

This doesn't really address the original question. What if I already have 2 WD VelociRaptor drives? The question is whether it's better to use them in RAID-0 or as a single drive.

[Oin]

There was a video that had 24 Samsung SSD drives raided together. Watch and want. youtube.com/watch?v=96dWOEa4Djs

[DHayes]

If it is something that I feel is worth backing up, then I probably don't want to lose it in the first place. I would likely opt for a different RAID method. With RAID0, every disk you add multiplies your chance of a data failure. It's good for cheap performance, but I wouldn't use it for anything I had a slight worry about.

[Paul McMillan]

His question is really "what should I do?". My answer addressed that. Bottom line, raid 0 performance is still probably better, but buying a single fast system drive is a reasonable thing to do in his case.

[NickAldwin]

Yep, I've already considered all that and am getting pretty good performers in those areas.

[David Spillett]

For bulk transfers I've found that software RAID0 (under Linux at least) performs as expected (i.e. pretty much the same as hardware RAID0). There are stripe width and read-ahead settings to tweak, which may help if you find a RAID0 arrangement performing disappointingly. Not being able to boot of software RAID0 is likely to be an issue Nick's plans though. And the inherent risk of any RAID0 arrangement, of course.

[Josh]

I think David is underplaying the risk of RAID0. If either drive fails you lose ALL DATA ON THE ARRAY. Thus you are doubling your risk of data loss. MAKE VERY FREQUENT BACKUPS! I have a RAID0 array and I treat anything on it as temporary. If you want speed and redundancy use RAID5 or RAID10. (I use RAID10 in my servers)

[David Thornley]

@Josh: In my experience hard drives don't fail all that often, so twice the chance of failure isn't that big a deal. Your backup strategy should depend on how much work you're willing to lose more than how likely you are to lose it.

[David Thornley]

With a good backup strategy, a drive failure is a matter of time, replacement cost, and inconvenience. I wouldn't want to lose stuff, so I back up to an external drive. If the internal drive fails, I haven't lost any creative work.

[Josh]

@David: Then maybe I experience your share of failures ;-) I experience at least two hard drive failures a year, if not many more. Then again I deal with a fair number of drives, so YMMV.