Why RAID is (usually) a Terrible Idea

uOpt said:
I should probably hack support into FreeBSD just to claim first base.
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If you do, send a nose-thumbing email to Areca, Promise, Highpoint, LSI, the Linux folk, the other BSDs, et al ;) Nothing like a good old-fashioned flame war to get the ball rolling...
 
Volkum said:
Well since I happen to be running 4x320GB and 4x250GB drives in 2x RAID5s...

Personally, it's much easier to mount two logical drives (one for DVDs and the other for TV shows) than to mounting 8 individual drives and having a mess with regards to organization.
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Or if you have a folder that won't fit on one hard drive. The last encoding project I worked on started with 700GB of music files, all in one iTunes library. (It's a sad state off affairs when you use a quad-core box to grind through ID3 tags.) With a stack of 400GB drives in a RAID-5 array, everything is groovy and I'm protected against random drive failure. Otherwise, I'd still be waiting for Hitachi to release the 1000's. :)
 
Just today, a coworker asked me about RAID. He wants to clone his HDD to protect against a failure and said his motherboard supports RAID. I told him he shouldn't really bother with it. And if he still wants to, then he should buy a $300 RAID controller and not use the "freebie" feature included in his HP computer's motherboard. I said his best bet is to buy a 2nd HDD (of the same size or larger as his primary HDD) and use Ghost to run weekly (or even nightly) backups.

He also asked me in theory, could one use RAID between an internal hard drive and an external one (via USB). I figured as long as the RAID controller supports it, it shouldn't be a problem, but I told him I wasn't positive on that. What do you say?
 
beowulf7 said:
He also asked me in theory, could one use RAID between an internal hard drive and an external one (via USB). I figured as long as the RAID controller supports it, it shouldn't be a problem, but I told him I wasn't positive on that. What do you say?
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He doesn't want to do that. Continuous cloning to a single location doesn't help at all. Suppose you corrupt the version of a document on your raid 1 array. Boom, the other disk has a corrupt version as well. With a periodic Ghost (or even better, incremental backups!) you could restore an older version to recover from this.
 
unhappy_mage said:
He doesn't want to do that. Continuous cloning to a single location doesn't help at all. Suppose you corrupt the version of a document on your raid 1 array. Boom, the other disk has a corrupt version as well. With a periodic Ghost (or even better, incremental backups!) you could restore an older version to recover from this.
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I think he just wanted to clone against failure.

You don't need a $300 raid card.

For a simple raid setup:
sata: http://www.ewiz.com/detail.php?name=LS-3041X (119 through froogle)
or http://www.newegg.com/Product/Product.aspx?Item=N82E16816116030

ide:
http://www.ewiz.com/detail.php?name=3WA-7006-2 (probably cheaper through froogle)

He should _also_ have a backup solution, preferrably on a different machine/removeable drive.
 
^ Thanks for the info. I'll pass him those links if he decides to go forward w/ the RAID. Given that 500 GB HDDs are so cheap these days ($110 last time I checked), I'll suggest to him to get that instead of a smaller HDD and RAID. Maybe get an external enclosure and then perform periodic backups w/ Ghost and then store that "external" HDD in a safe.
 
I still think RAID is not the best for home users because it is a bit higher maintenance, but it definitly depends on the situation.

Personally, I run my desktop with a Raptor 150gb Drive. Runs as fast if not faster than drives in RAID-0 and I do not have to worry about controllers and higher failure rates (2x the drives to fail). I have never really though RAID-0 to be a great thing, the drive failure rate being doubled just makes me think twice (but this is my opinion, many other use it and it works great for them).

I also run a server with 2x SCSI RAID-1 Arrays (a 9gb one and 36gb one). These are used for backing up my main machines which I think works great. That way I have: Backup from my main drives to another machine so virus, drive failure, corruption, etc. cannot get to it AND I have a mirror so if one of the drives goes in my backup it cannot totally F up my backup if something goes wrong with my machine and the backup drive at the same time.

One other thing, many do not setup good monitoring with their RAID arrays, this is ESSENTIAL since you would never know if one disk went down without it and then you have no extra security :confused:

Also, I am 100% for dedicated RAID cards, onboard raid has always been flakey at best IMO.
 
I think some people miss the point about the "better" RAID solutions (hardware raid controllers from a respected manufacturer and I would also count Linux software RAID in, but not FreeBSDs): you can actually trust it's raid-1.

The point about getting a $400 card for raid-1 is not that you get "hardware support". These days your CPU can easily do RAID-5 for a single array of 7200 rpm disks, with a max of 20% on one of your CPU cores.

But the junk, namely most of the onboard sata raid stuff, is suspected and has been caught destroying raid-1 by e.g. not getting error conditions wrong and then at a reboot sync the bad disk's contents over the bad one, or by just refusing to start the raid, or by kicking disks out of raid-1s for no reason (which gives you a vulnerability window equal to the time of re-sync in which you lose all data).
 
Ive been running 2x raptors in raid0 for the last 4 years without any problems.... I bought them when I didnt know better, I think its overrated in the fact that for everyday home use, its not all that much faster especially if you factor in the cost and risk......

I think alot of people doesnt understand exactly how raid 1 works ( im one of them ), when the hear the word " mirroring" they assume that thier data is 100% safe.... what they dont realize is that if you corrupt the original drive, you will corrupt the back up drive as well...... Unless you need to be up and running right away after a hard drive failure, raid1 is unneccesary.....
 
luihed said:
Unless you need to be up and running right away after a hard drive failure, raid1 is unneccesary.....
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Or if you want protection for hard drive failure. RAID-1 serves no protection as for what gets done to the drive via software (Virus, Corruption, Deletion, etc.) but offers a lot of physical protection as you have two exact copies of the same data on two independent drives.

I do think people exagerate it though, many think since they have RAID they are protected and need no backups, when in reality one virus could wipe them clean!
 
RAID isn't a substitution for backups, it just helps with hardware failure...

for example if you have a RAID 1 in your home file server and one drive fails... then you can rebuild at your leisure and still have access to your files. You should still have a copy of that data some where else.

If it wasn't raid-ed, then you would have to fid a drive and rebuild right there on the stop and then restore from backup...

I look at it like this: RAID (1 or 5) saves you some time and saves you some headaches if you have a hard drive failure.
 
budec said:
RAID isn't a substitution for backups, it just helps with hardware failure...

for example if you have a RAID 1 in your home file server and one drive fails... then you can rebuild at your leisure and still have access to your files. You should still have a copy of that data some where else.

If it wasn't raid-ed, then you would have to fid a drive and rebuild right there on the stop and then restore from backup...

I look at it like this: RAID (1 or 5) saves you some time and saves you some headaches if you have a hard drive failure.
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or if you are in an infastructure that uses data the changes alot, it can provide a hardware assurance backup between nightly backups :)

It is no replacement for a backup, but serves to protect from one of the major causes for a need of a backup...drive failure.
 
RAID is useful is some situations...

I used to be against RAID 5... I have had corrupt file tables and lost 90% of my data before with a hardware RAID 5 solution.

I then went to JBOD which was fine when I had 400gb drives full of music, movies and programs...

Once I started to replace my 400gb drives with 750gb drives, the time cost of loosing one drive almost doubled. I would have to rerip almost double the amount of movies and music from one disk loss. This made me change my mind.

I have since purchased a RAID NAS unit and have been extremely happy so far (knock on wood) with a RAID 5 setup.

I can loose a disk and save some time from reripping... Of course I am open to controller/NAS unit failure but I can get a replacement and should have a good chance of data recovery.

If some odd occurrence happens and I loose all my data, oh well I will have to rerip everything.

My thought is that harddrive failure will probably have the greatest chance of occurring, and I have that covered. Everything else I consider act of god and not worth worrying about.
 
dandirk said:
My thought is that harddrive failure will probably have the greatest chance of occurring, and I have that covered. Everything else I consider act of god and not worth worrying about.
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I believe the same. Virii -- more or less protected (I've never had a problem with that). Accidental deletion -- nah, that doesn't happen to me and if it does, it's a minor quibble. Filesystem corruption -- lets hope filesystems nowadays are pretty damn reliable compared to the possibility of hard drive failure of multiple drives.

Then again, I've never had a drive ever fail on me either. Some people would call me lucky.
 
Cyrilix said:
I believe the same. Virii -- more or less protected (I've never had a problem with that). Accidental deletion -- nah, that doesn't happen to me and if it does, it's a minor quibble. Filesystem corruption -- lets hope filesystems nowadays are pretty damn reliable compared to the possibility of hard drive failure of multiple drives.

Then again, I've never had a drive ever fail on me either. Some people would call me lucky.
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I agree. Knock on wood, I haven't had any virus, spyware, or any other kind of malware problems and never accidentally deleted or overwrote an important file. But I've had 2 HDDs flat out die on me since 1998. :( That's why I bought a redundant HDD, but rather than RAID them, I manually clone one HDD to the other using Acronis. However, I don't do it frequently enough. :eek:
 
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