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Comment from Art on 2009-08-05

2009-08-05T19:25:00Z

You are both sort of right, RAID stands for "Redundant Array of Independent Disks". It was "Redundant Array of Inexpensive Disks" but the companies that make RAID equipment did not like the word "Inexpensive" since it made RAID sound cheap. And Sandy is sort of right because "Drives" are also called disks. But I am still back in the time when URL stood for "Universal Resource Locator"

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Comment from Sandy Smith on 2009-07-25

2009-07-26T03:53:48Z

I was always told RAID meant, "Redundant array of independent drives." Weird...

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Comment from Alan on 2009-07-17

2009-07-17T13:22:26Z

As a tech, I saw one of the big mistakes that a computer company can do and it was the Now gone MPC computer. In the end I got some PCs from them that had Vista on them and my company wanted XP on them. Well I tried to install the XP software and it would not. I emailed their tech support and after the run around one of their final techs said the RAID in the BIOS was on. I went in and turned it off and was able to install XP. Now RAID is a bad thing when you have one drive. If you really need a RAid system in your house I hope your related to the edisons for your electric power. I know there are people out there running a server at their house, but ask why risk it all just to use RAID on either a server or a home PC. In the early days of RAID at companies you were risking allot I saw RAID not work I know these days they are much better and are working now. I've been working on computers for over 30 years and still don't see people keeping it simple. Home users with drives so cheap you can pick up a stand alone drive turn it off and on when you want, save time, save electric, and save money. If you have files save them there and then if you don't use the files then put them on a cd, dvd, or blue-ray disk. If your a a home computer user and your spouting I have a RAID on your home system then your just wasting your own time. Rule of Thumb RAID bad for home users, RAID good for Bussiness servers at companies. Drives are going to die and your going to have to replace them, same with motherboards, and other computer parts they don't last forever. Keep your computing simple thats what computing was supposed to be all about.

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Comment from Leo Hasbrouck on 2009-07-15

2009-07-15T23:23:14Z

How do I get rid of RAID? I keep getting a message that it has stopped working. I do not want it.

That depends entirely on your system (and the exact error message you're getting). Typically it means a BIOS/Raid controller change and a reformat/reinstall of your system from scratch.

- Leo
16-Jul-2009

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Comment from SalemCat on 2009-07-15

2009-07-15T18:47:29Z

Like RAID 5? Don't forget your MOTHERBOARD can fail, too! If it does (a very frequent occurance with the recent rash of Bad Capacitors) you'll need to go out and buy another Motherboard with the same RAID CONTROLLER to recover your Data. I use only RAID 1, so I can remove a Mirrored Hard Drive and read it on any Windows PC.

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Comment from Chris Awad on 2009-07-14

2009-07-15T02:27:56Z

The "software" raid you are talking about David can be created using windows dynamic disks where disk manager in windows can create stripped partitions/etc. I honestly dont like dynamic disks.. I rather have it done the "right way" during the boot process so partitioning tools can work from bootable CDs, etc, otherwise if windows fails, the stripped partitions might be in trouble...

I honestly like the idea of RAID5 or RAID 1+0.

RAID5 requires at least 3 drives to work and its basically mirroring between 3 drives with a parity section on each drive with information from at least 1 other drive dedicated. If 1 drive dies, the RAID will continue to work flawlessly with a small performance drop (still faster than just 1 drive). If a 2nd drive dies, your in trouble. This raid is n-1 drives in disk space.

RAID 1+0 would require at least 4 drives and is most definitely the fastest and most protected. It would be n-2 drives in disk space, but this RAID would only fail if all the drives fail on a single strip (highly unlikely).

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Comment from David on 2009-07-14

2009-07-15T01:20:00Z

Not really RAID related but addressing a comment by Corneliu. I'm impressed that at least some people bother to do a backup. However, I do a lot of work in one day; six to seven times that in one week. I can't afford to lose a week's work on the day before doing a weekly backup. That's why I do a daily backup - with a sensible protocol and good backup software, it literally takes less than 10 minutes to do an incremental backup.

For the record, I use RAID 5.

Finally Leo, you mentioned a "piece of hardware" - a RAID controller - which can be either a discrete card OR built in to the Mother Board. However (and I guess you omitted it to avoid confusion) there is also Software RAID if your readers care to investigate.

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Comment from Chris Hingee on 2009-07-14

2009-07-15T00:03:19Z

RAID 0 is NOT a bad idea if you need the speed and if you have fault tolerance system.
If I needed RAID 0, I would also mirror the drives. This would double the cost of hard drives, but it is worth protecting your data.

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Comment from C. W. Joiner on 2009-07-14

2009-07-14T21:45:01Z

Your analysis of increasing your failure rate from 1 out 1000 to 2 out of 1000 is even worse. Using an MYBF calculation, the failure chances increase to much more than 2 out of 1000. But your thought, as usual, is great.

I did not mean to imply that the actual failure rate was 1 in 1000. Just using easy-to-understand numbers for comparisons purpose.

- Leo
15-Jul-2009

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Comment from Corneliu Coterbic on 2009-07-14

2009-07-14T20:05:13Z

I use RAID 0 for 4 years and I am very pleased with the performance (speed) BUT I use a external HDD for weekly backup. If you think only at bad things you do not dare to cross the street.

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Comment from Robin Clay on 2009-07-14

2009-07-14T19:23:31Z

Simcha Wachtel wrote:"file system corruption that is easily resolved by running scandisk from the Recovery Console"

[Cough, Splutter !]

My hard drive managed to acquire a crosslink, and when I used ScanDisk, I ended up with - wait for it - seventy THOUSAND "new" files ! The cross-link had destroyed my "Pictures" folder. So I still have the data - but as far as I know, I can't re-assemble it !

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Comment from Wookie on 2009-07-14

2009-07-14T19:09:05Z

Leo villanizes RAID 0 saying it is a "bad idea" and a "serious risk."

WHY do we think a 0.2% chance of failure is so much worse than a 0.1% chance? Either way, we're talking about a fraction of a percent.

Odds are much better that a person will lose data due to user error, malfunctioning software, or malware.

The real bad idea here is to not have any backup plan.

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Comment from snail on 2009-07-14

2009-07-14T19:08:04Z

I'll throw out a speculation at improving performance and a possible backup scheme/arrangement: If you buy into a computer with multiple drives, use the fastest one(DMA and spindle speed and latency) for either or the system and cache(swap file); or, if you have enough fast disks, perhaps have the larger(GB) of the two(or more) be used to install the OS and applications. Use the other one(s) for user-created documents which you might: A)save copies of for distribution, B) delete or modifiy, C)backup for archive purposes(like entries corresponding to calendar dates...
In this set-up, from time to time make copies of all your: Documents and System files.
Perhaps one easy way would be(I haven't tried it. any recommendations or suggestions?) using a hard drive duplicator - - or boot into the system with another OS(LiveBoot Linux distro's make sense) and access the Hard Drives(system install and software install, and documents) to copy them to media(CD's, DVD's, Blu-ray... other hard drives(used for backup only) or best of all, UFD's(flash drives).
Optical disks have been a pain for me as there are stupid naming conventions and 'folder depths' which interfere with copying...I don't think I've had any problems copying from NTFS to a UFD(I think the flash drive was FAT format...)
side note: if possible(without affecting performance or stability) upon a clean install consider installing applications onto a separate drive... many programs are highly customizable and are used in a way which their file creation takes place in the installation folder. In any event, my 'program files' folder contains many hundreds of MB of data, so much of which I depend on for my software's use.

Ideal(under my wild speculations) disk arrangement:
.)Fastest disk, size probably not more than 10GB?: Cache(swap file)

.)Faster disk(or same speed as above), size 4 - 15 GB for system only(maybe you have a higher GB demand than I...

.)Fast disk(or same as above two), size 10- 100GB, depending upon how many apps you install(maybe less than 10GB?).

.)'slower' disk(s), size 100 + GB(depending upon usage): storage of user files(backed up manually, loaded into/from such folders as "My Documents," "My Pictures," et cetera...

.) additional disk for more storage of documents, perhaps additional disks can be used for organization(one disk for videos, one for text; each disk tailored to the size needs for its content).
+) at the document level it might be better to have one 100GB hard drive for all document storage and from time to time(or daily or more frequently for the paranoid with a NAS) back up to other media from this HD

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Comment from Simcha Wachtel on 2009-07-14

2009-07-14T16:58:33Z

I'd go a bit farther and suggest that RAID 1 or 5 are also bad ideas for the ordinary home user. One of the more common problems I've seen in servicing Windows computers is file system corruption that is easily resolved by running scandisk from the Recovery Console. But if the boot volume is on a RAID, the user will need to load drivers in order to access it from the Recovery Console. It can become a mess. On occassion when I didn't have access to the correct drivers or the user had no floppy drive, I've had to break the RAID, fix the file system and then rebuild the RAID. Not for the faint of heart and NOT for the ordinary user.

RAID is also sometimes seen as a substitute for backup and it shouldn't be.

As far as the speed or storage space benefits, I think they are minor for most users.

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Comment from Nick on 2009-07-14

2009-07-14T16:13:51Z

O.K.,
So I'm a victim of Raid 0. My old MB had a built-in controller and I foolishly used it. Sure enough one of my WD drives failed. (I think it's in the PCB and not the platters, but anyway)
My question is: Can the data from one drive be recovered professionally to be synced with the remaining drive, or do both drives need to be "sent in"? Of course that's double the GB's for recovery cost.
RAID 0 - never again!

Both drives would be required. Further, the service may need the raid controller as well, since there's no standard about how the data should be split across the drive. This type of data recovery on Raid drives gets very expensive very quickly, if they'll even do it. It's much more involved than just recovering two drives worth of data.

- Leo
15-Jul-2009

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Comment from JIM E on 2009-07-14

2009-07-14T15:59:53Z

RAID - SPLIT PERSONALITY- NEVER WORKS

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Comment from Greg Bulmash on 2009-07-12

2009-07-13T05:44:37Z

I've heard that RAID 5 doesn't give you the speed of 0 or the security of 1, just the illusion of both.

Just do RAID 10. All the redundancy of RAID 1 with all the speed of RAID 0.

Of course, redundancy or not, there's no substitute for backing up your data. Having a single drive in a RAID 0 array go kablooey is no different than having the one drive in a single drive system go kablooey. You're still going to have to restore from a backup.

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Comment from Steve on 2009-07-12

2009-07-13T05:08:26Z

Simon, I know that the combined probability isn't 2, but how did you get 1.9989(9) in 1,000? I get 1.999.

P(no failure in single disk) = 0.999
P(no failure in either disk) = 0.999 * 0.999 = 0.998001
P(failure in either disk) = 1 - 0.998001 = 0.001999 (or 1.999 in 1,000)

Did I forget something? I wouldn't be shocked.

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Comment from Simon on 2009-07-12

2009-07-12T22:50:12Z

> If one drive has, say, a 1 in 1,000 chance of failure, then two drives have a 1.9989(9) in 1,000 chance.

As a maths geek I feel obliged to make an unnecessary, pointless, and anal correction: If one drive has a 1 in 1,000 chance of failure (in some time period), then two drives have a 1.9989(9) in 1,000 chance of either failing (where brackets denote recursion).

(Yes, I know you know that and were just approximating it as 2, Leo, but it's good not to get your readers into the habit of assuming probabilities are additive: otherwise they end up thinking things like "So if each drive has a 75% chance of having failed by the end of 20 years, then two drives have a 150% chance of one of them having done so" (the actual figure would be 93.75%).)

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