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Raid Issues

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March 9, 2010 10:47:55 PM

Hello,
Just got 2 new WD7501AALS Windows7 32 bit, and running RAID (mirrored) HD's are 1 month old did install this last week and things were running smooth now today computer is saying issue with one of the drives (CRITCAL) when i go into raid utility one of the drives states that is appears to be missing or disconnected. When I am in Windows I can see the drive and put that drive online and even access the data contents on it, but why cant i rebuild the array? Also running onboard raid controller motherboard is Asus M3A78-EM

More about : raid issues

March 10, 2010 12:54:53 PM

Firstly i would make a backup of the data on that array as it sounds like one of the disks in your array has just died.

Figure out which drive it is and pull it out and stick it in another machine if you can.

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March 10, 2010 2:27:19 PM

Sneef,

Why is it that the drive is still accessible in Windows? But why does the raid controller see it as missing. Unfortunately, I cant use WD Data Life Guard tools because of the raid configuration.
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March 10, 2010 2:33:00 PM

Also i dont have another machine to test the drive in. I really dont wanna shell out another $80 for another drive
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March 11, 2010 1:21:42 AM

Sorry i misunderstoof what you were saying.

I would backup to a external drive and rebuild the array from scratch and repartition etc. Drastic i know but you wanna know WTH is going on right? Nothing more reassuring than watching it rebuild the array and giving you no errors.

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Best solution

March 11, 2010 1:41:58 AM

Also let me give you some advise that i just learned in another thread i posted where i was pulling my hair out with RAID.

If the data is important enough to protect with RAID 1, or 5 in my case, then it is STILL important enough to keep two copies on two seperate storage setups.

Here is what user sminlal had to say in my thread.

Quote:
If you're using RAID to prevent data loss and if you're NOT doing backups to external media, then you have your priorities wrong. You need external backups to protect against risks to your data that RAID can't safeguard.

With RAID 5, the more disks you use the more at risk your data is. This is because more disks = bigger chance of having one of them fail, and bigger chance of a 2nd drive failure before you can recover.

And don't forget that RAID 5 can only recover if it can successfully read EVERY sector from EVERY OTHER drive. Since hard drives are spec'd to have an unrecoverable read error approximately once in every 10^14 bits read, that gives you something like a 10% chance of being unable to read a sector from a 1TB drive. Multiply that by 4 drives and you're getting uncomfortably close to even odds that your data won't be able to be recovered.

I say all this because (a) when you have a lot of drives then handling drive failures is just going to be a fact of life, (b) therefore you need a well tested procedure for recovering from drive failures instead of thrashing around to see what works while your data is at risk, and (c) IMHO you shouldn't be relying on RAID as the end-all and be-all strategy to protect your data. In fact it may be that eliminating RAID altogether and beefing up your backup and recovery strategy may be a lot simpler in the long run.


the thead is HERE

Also i am going to make a semi educated guess at your problem, as it may be the same problem that caused my RAID 5 array to become degraded (missing 1 drive out of 4, but still running) Google your drive and TLER and see what you find...

Now TLER is new to me and i do not claim to be any kind of expert, but here it is boiled down simple as far as i can get it...

Sometimes your drive kinda burbs/pauses/falls asleep for a period of time and gets ejected from a raid array coz it "went bad" when it actually did not. Up till Sep 2009 WD Caviar drives had TLER tuned off (TLER helps with this issue) but you could get a tool and turn it on in the bios of the drive... meaning you could use retail caviar drives for RAID... since Sep09 they disabled the abilty to turn it on or off and so retail Caviar drives are now in some ways not suitable for RAID, thats not to say they dont work... my RAID 5 array lasted for 4-5 months of hardcore use. and my RAID 0 boot partition is still working *crosses fingers*.

WD sell drives that are RE model drives... these are more expensive and are fine for RAID i hear...

You might have better luck by just have two drives and doing your own mirroring, you get more space this way because your not mirroring the OS and apps installed, you can mirror docs/pics et al that you really value.
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March 18, 2010 11:18:45 AM

Best answer selected by SlayerXL095.
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