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Basic RAID 1 Set up Question

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August 18, 2011 11:28:53 PM

Hello All,

I would like to set up RAID on my PC. I have a 485GB drive as my primary drive with a 300GB drive as my second drive. All my apps are on the 485GB drive and my data is on the 300GB drive. My thought is to replace the 300GB drive with a 1TB drive and set it up in RAID 1 (Mirroring) with the 485GB drive. From what I have read in my manual, I can do this without reinstalling the OS or having to reinstall my apps. Am I on the right track? Can I keep the existing 485GB drive and establish the RAID or do I have to reinstall the OS? Any problems with the two drives being different sizes? Would I still be able to use the full capacity of the 1TB drive? Thx
a c 530 G Storage
August 19, 2011 3:10:53 AM

Yes, you can use different size drives in your RAID, but for best performance you would want them to be the same make, model, & size.

I’m no expert in RAID but I thought that when you initially create a RAID array all partitions on all drives in the array being created are deleted. Double check your motherboard manual and/or backup your data to be safe.

The capacity of a RAID-1 array is one-half the sum of all the drives in the array.
So your unformatted capacity will be 742.5 GB.
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a b G Storage
August 19, 2011 7:12:55 AM

That is not correct, if you were to mirror (RAID1) those two drives you would have a total capacity of 485GB. It is exactly the capacity of the smallest drive in the mirror.

If both drives are identical it would be 1/2 the total capcity so essentiall you would be wasting about 1/2 your 1TB drive. Any RAID configuration is really best suited for identical drives. If you are doing this for redundacy purposes, consider imaging 1 drive to the other on a nightly basis.



If you really need to run RAID, although I don't really recommend it here, can I suggest running your 2 smaller drives in RAID 0, this will give you 600GB of RAID0 (better performance) space and then image this drive to your 1TB drive nightly for redundacy. You will have 2 independent copies of all your data on the 600GB (better than 485GB you woul get with RAID1) and you'll have roughly 400GB left over that is not redundant all while increasing your performance.
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a c 530 G Storage
August 19, 2011 7:50:44 AM

tokencode said:
That is not correct, if you were to mirror (RAID1) those two drives you would have a total capacity of 485GB. It is exactly the capacity of the smallest drive in the mirror.



Sorry about that. I was looking at a table in Wikipedia where it stated that the Space Efficiency of RAID-1 arrays is 1/n, where n = number of drives. There was no notation for arrays with different size drives.

I should have checked multiple sources of information. :ouch: 

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August 19, 2011 12:34:30 PM

tokencode said:
That is not correct, if you were to mirror (RAID1) those two drives you would have a total capacity of 485GB. It is exactly the capacity of the smallest drive in the mirror.

If both drives are identical it would be 1/2 the total capcity so essentiall you would be wasting about 1/2 your 1TB drive. Any RAID configuration is really best suited for identical drives. If you are doing this for redundacy purposes, consider imaging 1 drive to the other on a nightly basis.



If you really need to run RAID, although I don't really recommend it here, can I suggest running your 2 smaller drives in RAID 0, this will give you 600GB of RAID0 (better performance) space and then image this drive to your 1TB drive nightly for redundacy. You will have 2 independent copies of all your data on the 600GB (better than 485GB you woul get with RAID1) and you'll have roughly 400GB left over that is not redundant all while increasing your performance.


Thank you all for the helpful replies. As another option, I could replace my data drive with a 1TB drive and perform back-ups on a daily, weekly or monthly basis. Daily is probably a bit much as there are really only a few files which change daily which would require frequent backups. Quicken comes to mind but everything else would be ok if I just backed up monthly. Plus I can skip the hassle of setting up raid which sounds appealling.

Anyone have a suggestion on decent imagine software?
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