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I am currently trying to convert my drives from just a bunch of external disks, each one individually shared from my (CentOS) server into a RAID array (ideally, RAID 5).

At current, my drives are:

  • 2.7TB (0TB used)
  • 2.7TB (2.6TB used)
  • 2.7TB (1.1TB used)
  • 0.9TB (0.93TB used)
  • 0.9TB (0.26TB used)
  • 0.9TB (0.8TB used)
  • 460GB (400GB used, this one I am considering binning though)

Now, what would be the best approach in creating a RAID array so that I can create a single redundant disk without formatting all of them and starting from scratch (I will need to preserve the data, so is there some method of slowly creating the array then extending it drives as they get their contents emptied into the new array)? Or is RAID not the way to go?

Also, will I be able to create an array comprised of the 3x 3TB drives and the 3x 1TB drives to create a single 9TB drive with 3TB of redundancy?

  • wait so you want to do this with drives that have existing data on them? I don't know if that is an option btw.. I could be wrong, but usually when you build the array there are not any options for leaving existing data that I have seen on Windows or Linux. – Richie086 Mar 20 '14 at 13:45
  • well, i know I can't build the array without formatting them, but is there a way that I can gradually build the array, drive by drive (possibly starting on some other raid level, then changing later, if thats possible) as I am able to copy data off of one drive and into the raid – topherg Mar 20 '14 at 13:47
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    I think you would be better off using something like ZFS since you have different disk sizes rather than trying to manage two raid 5 arrays. With raid 5, the 1tb array would only have 1862.45 GB (less than 2 TB total) usable storage. The 3 disk, 3tb array would have 5587.37 GB of usable storage. See ibeast.com/content/tools/RaidCalc/RaidCalc.asp for a raid space calculator – Richie086 Mar 20 '14 at 13:48
  • pretty sure that is not an option. If you have a decent internet connection you could always pay for AWS online storage or get a premium dropbox account so you can store the data offline temporarily. Not ideal, but it does give you an out and saves you from having to buy a bunch of new drives (which would be the best option IMHO, but obviously the most expensive). – Richie086 Mar 20 '14 at 13:51
  • ah damn, cheers for the help :) – topherg Mar 20 '14 at 13:52
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Windows does not like to mix drive sizes with raid.

You could put the first three in raid 5 (2.7*2 for total storage ) You could put the second three in raid 5 (0.9*2 for total storage ) and 'binning'="in american English 'throw away' " the 7th.

This leaves less total storage then you are currently using, so you would have to throw stuff away.

That's about the best you could do with Windows.

There are oodles of other options in Linux.

  • I will be using CentOS to do that, but that's what I was thinking of doing. Would I be able to raid 0 the 3 1tb drives into a 3tb drive, then add that to the other 3t drives? – topherg Mar 20 '14 at 13:34
  • Raid0 is actually 'aid0', since as a stripe, it has no redundancy. IMHO, one should never use Raid0 alone. – jerrylagrou Mar 20 '14 at 13:38
  • couldn't agree more, but I was just going to "aid0" them so that they could be used with the other 3tb drives in a raid5 – topherg Mar 20 '14 at 13:40
  • Is this still true in late 2017 ? – Dan Chaltiel Nov 6 '17 at 7:35
  • These answers are fundamental to the meanings of Raid0, Raid5. They will always be true. – jerrylagrou Feb 14 '18 at 21:17

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