I thought RAID 0 gave you performance while RAID 1 + 0 gave you slightly less performance than RAID 0 but with added security due to backup :shrug:

RAID mirrors, and as such is not a backup. The following problems exist when using RAID as a backup:

1. RAID controller corruption/failure

2. mirrored corrupt data

3. Accidental/Malicious deletion

4. System destruction

(I'd say that lack of file versioning also belongs in here, but some may disagree about the necessity of file versioning for a backup)

A true backup has none of these problems (with the possible exception of 1 if the backup server also uses RAID for whatever reason).

Like I said in the quoted post, the best RAID can do is offer increased data availability (due to mirroring), but this does not translate into data reliability.

Problem 1 is strictly RAID-related, problems 2 and 3 happen any time mirroring is used for your backup (hence mirroring is never a backup solution), and 4 happens whenever your backup is located on the same system as your original data. File versioning increases your window of recovery.

I did think about adding "... but it's not a substitute for backing up", but didn't as I figured the topic was about drive failures. :shrug: Checkpoints are useful for those of us who are idle, however, and directory-to-directory backups aren't entirely unreasonable on a storage medium with decent integrity. Edit: but just to be clear, this sort of thing still isn't a proper substitute for backups: they should still be done at least occasionally, and not on a medium that's permanently present in the same computer. No, I don't take my own advice quite as thoroughly as I should.

RAID5 can be slow at writing if not ideally optimised for the filesystem using it. A number of them get around this problem by merging the two in some way, such as Sun's ZFS and the Veritas storage system. I prefer RAID6 as it has two XOR devices per array, though that's probably getting a little paranoid.


I hope nobody assumed I was suggesting that RAID is a substitute for backups, as it absolutely is not, as you rightly point out. The only substitute for a backup system is another backup system; take a worst-case situation where a big enough power surge fries your computer, no RAID system is going to recover if all its HDDs are dead. Write caching should definitely be disabled using RAID (in fact IMHO it should never be enabled unless the data really is considered disposable) though with the various types of command queuing available on SCSI and SATA storage, there should be little performance penalty (if any) by disabling it anyway.

I would strongly disagree that its only place is in production servers, though: few if any of us backup as regularly as we probably should, and I have experienced both the data-loss and hassle of recovering a small server on more than one occasion. I don't intend to do it again if I can possibly avoid it.

It's my personal opinion that I don't expect everyone to agree with. By far the most common problem I come across is system/disk failure, like the OP is asking about. Also the most common RAID I come across in the consumer market is RAID 0 (which I think both you and I would agree is NOT a good thing for the average consumer). These combine to make data recovery range from not fun to impossible. I find RAID introduces far more problems than it is worth on the consumer level, and given that mirroring can be done on the OS and software level, RAID for consumer data redundancy I see as just a headache.

I do agree that not enough people do do regular backups. I dream of a day when there is a NAS in every house

That's a point. I go rather pale on other people's behalf when they start to talk about their grand new RAID0 set-up and I think to myself "half the MTBF of consumer grade devices. That's not good." I've gone down the software mirroring route with mixed results and finally settled on getting a RocketRaid card to do the job instead, which makes things like installations less painful, although even now they're still not as cheap as most users would probably prefer.


But what sort of RAID will it use? That's in essence what I use for all of my "pain in the backside to restore" type data, most of my stuff living on a range of network drives provided by a Unix server, but even so I still use mirroring on my games computer as I don't fancy the rigmarole of reinstalling the next time an HDD fails. That said, out of the 15 (I think) HDDs spread between my server and desktop, none have failed in the past 5 years, surprisingly: maybe I just had a run of bad luck before that.

I agree and I've never used RAID and don't know that much about that but I had always heard that it was good for protection, but of course I wasn't implying they substitue backups

Basic questions:

If you have 2 HDDs installed and are not using RAID, should the AHCI mode in the bios be set to IDE or AHCI?

If one drive runs out of recycle bin space, does windows7 automatically try to copy the rest of the files to the spare recycle bin space on the other drive, or does it pop up a permanent delete window?

We use Raid storage at the office primarily because it improves performance working with very large video and graphics files. As long as I can recall (since before 2000), Raid storage has been popular for video editing.

At work we have a one external Raid5 with SSDs and a separate, larger network Raid5 storage with HDDs (i think they are 10k RPM drives, not sure).

On my laptop I have dual Intel SSDs in Raid0, which is not the most secure configuration, but I back up my data frequently. The performance boost is worth it IMO.