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I am going to redo the drive configuration on my desktop and right now I am considering options. I have an SSD for the OS and vital programs and HDD's for everything else. I have two 2TB disks of the same type and another couple of various sizes. I am debating whether to RAID the two 2TB disks together in RAID1 for redundancy or RAID0 for performance. I will have a incremental backup plan in place on a separate removable drive I am just wondering if it is worth it to software RAID the two drives on the desktop.

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Whether to use RAID0, RAID1, or leave them as-is depends on how you use them. There are 3 factors to consider: performance, reliability, and capacity. Figure out your use-case, then choose the two most important factors.

JBOD ("just a bunch of drives"): baseline performance and reliability, maximum capacity. (Note: for special use-cases, JBOD can actually provide improved performance.)

RAID0: improved read/write performance at the expense of reliability, maximum capacity.

RAID1: improved read performance and uptime, but with only 50% capacity.

Use-case: storage

If you use the 2 TB disks just for storage, then RAID0's performance benefit is probably not worth the increased potential for data loss.

RAID1 can save you time in the event of a single-disk failure if you don't have to restore from backups, but your storage capacity will be halved.

JBOD is a good alternative if you want maximum capacity but don't want to risk losing your data all at once and having to restore from backup--you would be more likely to only lose half your data, so you could continue using the other disk while restoring the failed disk's data from backup.

Use-case: multimedia editing

If you regularly do some disk-intensive activity, such as video editing, on the drives, then RAID0 will provide some performance benefit (but not quite double) with an increased risk of data loss. If a disk fails at any time, you lose everything and have to restore from backups.

RAID1 will speed up loading files. If a disk fails, you might be able to hot swap a replacement disk in without any issues. If a disk fails during rendering, you can finish rendering uninterrupted.

JBOD can improve performance if you use different disks for your scratch disk and your workspace.

Use-case: home file server

RAID0 and RAID1 will both provide better read performance for people copying files off the server.

When people copy files to the server (for example, if you use it as a backup target), RAID0 will provide faster write performance, and RAID1 will provide about the same level of performance.

One interesting performance scenario is when you have multiple users accessing the file server. When two users happen to be reading or writing to two different directories at the same time, you'll get better performance if each directory is on a different disk. For example, if your first disk contains a bunch of videos and your second disk is a backup target for CrashPlan (or whatever network backup solution you use), you'll be able to watch a video while your computers are backing up, without causing your video playback to stall from disk thrashing.

Conclusion and other options

Of course, these are only a few potential use-cases, but they should give you some idea what to consider when trying to decide which type of RAID, if any at all, is worth the trade-off for you.

If you add 2 more disks, there is another option--RAID10 (or RAID1+0)--which provides the performance benefit of RAID0 striping with the redundancy of RAID1 mirroring. Unfortunately, it also reduces your capacity by 50%, so you would still only have 4 TB out of 8 TB usable space.

RAID5 is yet another option, but there is a performance issue known as the "RAID5 write hole," and with large disks you run a higher risk of a second disk failing during the rebuild process. RAID6 addresses this latter issue with 2 redundant disks, but is not as commonly supported with consumer-grade hardware or software.

One final note: I would highly recommend having redundant backups, regardless of whether you're using RAID. I've seen several cases in which an external backup hard drive failed and wasn't replaced immediately, and then the user's hard drive failed. Ideally, you should try to have an off-site backup and an on-site backup. You can implement this with two or three external hard drives that are rotated, or an on-site external hard drive and one or more off-site network backups. Personally, I use CrashPlan to make computers at 3 different locations backup to each other and to CrashPlan Online. CrashPlan also lets you target a local (internal or external) hard drive. Backing up to your own computers or a friend's or relative's computer is free, but the online service requires a subscription.

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I have been using RAID 1 (mirror) at home and work for years and it has been worth it because of relatively low hard drive costs (until recently). I buy the drives 3 at a time, 2 are the mirror and 1 is for backing it up. If one of the mirrored drives fails, I can use that backup one to replace it and get a new backup drive. I also have three other older Raptor drives configured as RAID 0 (stripe) for stuff I can afford to lose like games, page file, and encoding scratch space. I have never lost a drive at home yet.

At work I upgraded to RAID 1 with 2 TB drives and one of them reported a failure, so we did an RMA and got another one. It takes almost 8 hours for this size of a mirror to build the other disk. If the stuff you are doing is important and you can't lose time restoring from backups, and you can afford the extra disk, I would recommend RAID 1.

Another thing you can do is use the SSD as a boot/program files drive, and have your 2 TB data mirror separate, and backup an image of the SSD to that mirror, since the SSD will be much smaller and not take up too much of your mirrored space. Then you have backups of the SSD boot drive if it fails. Even with this you will still need to do backups of the mirror.

One more note about using an Intel Matrix RAID. These things seems to occasionally report that the disks need to be verified, and may even report that a disk is bad, even though it is not. I don't know what it is, but these controllers seems to be a bit flaky in reporting actual drive failures.

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    What I've seen with the Intel bit is that if Windows doesn't shut down cleanly it's prone to reporting the array as faulted. For a RAID1 that simply means it's a bit slow for a while while it does a needless rebuild. I've had it fault drives that appeared to be ok but it knew what it was doing--any such drive soon failed.
    – Loren Pechtel
    Feb 8, 2012 at 23:21
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You would benefit from a nice speed boost if you use RAID0 and since you're already doing incremental backups then a RAID1 seems redundant unless your working with highly valuable material at home. Having run both types of setups at home, the RAID1 was noticeably slower than the 0.

Once I also lost a drive on a RAID0 array many years ago. Total loss except for what I had backed up on a third drive in the computer.

Basically it boils down to redundancy or speed. Whichever you prefer should be your choice.

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RAID 1 will boost your read performance and won't normally impact your write speeds. The details depend on the implementation. I routinely used this to improve database performance.

RAID 1 will also let you:

  • upgrade your hard drives
  • survive some disk failures
  • take snapshots of your system without taking it offline (depends on the implementation)

RAID 0 will double the risk of hardware failure causing catastrophic loss.

Backups are always necessary. No RAID level will help that.

Disclaimer: My home system is software RAID 1

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