Spanning two existing Software Raid 1's

[iamthemoose]

I have a little NAS running on this board: http://www.gigabyte.com/products/product-page.aspx?pid=4716#ov

with

2x wd red 4tb in raid 1

and

2x wd red 6tb in raid 1

I bought what I could afford as I went along. 8gb ram, and about the cheapest CPU I could find. Running windows 10.

Both raid arrays have data on them and I'm hoping someone knows if these are spannable without reformatting?

 

I'd like to span the arrays together so I have, essentially, one 10tb mirrored array.

 

Is this possible or do I *have* to go buy a drive, (or two depending on how paranoid i'm feeling) copy everything off both arrays to the new drive, and rebuild from scratch in Disk Management?

TIA

[Captain_WD]

31 minutes ago, iamthemoose said:

~snip~

Hi there

 

Do you have your RAID currently set up from Disk Management or you used the onboard RAID options in the BIOS? 

Either way if you are using a simple basic RAID1 you would need to reformat the drives if you change the RAID mode from RAID1 to Span. 

 

One thing I could suggest (if the data on the 6TB Mirror array is below 4TB) is the following:

- Take out one 4TB drive from the RAID1 and back everything up from the 6TB mirror on it.

- Reformat the 6TB drives so they are not in a Mirror mode anymore but are rather standalone drives.

- Restore the data from the 4TB drive on one of the 6TB drives.

- Place back the 4TB in the 4TB Mirror array and rebuild it. 

- Back up the data from the 4TB Mirror array on the empty 6TB drive (or on the other drive if there's enough space).

- Reformat the 4TB drives so they are not on a Mirror mode anymore but are rather standalone drives.

- Restore the data from the 6TB drive (the one that you used for backing up the 4TB Mirror array) on one of the 4TB drives.

- At this point you should have 4 independent drives, one 6TB with the data from the 6TB Mirror array and one 4TB with the data from the 4TB Mirror array. 

 

Unfortunately, you need to check if you have the ability to create a RAID1 array without the mirroring part so you can later expand it. Otherwise you would again need to reformat all four drives in order to achieve what you wanted. 

 

This is a longer but more simple way of doing what you want. 

 

A shorter, but more expensive way would be to get an external drive and back everything up to it and then restore the backup after you've configured your desired RAID array. 

 

Mind that combining two RAID volumes in a single RAID (RAID0s in a RAID1 or Span volumes in a RAID1) greatly affects the safety of the data as this adds quite a lot of failure points and I would advice against that. I would leave the arrays as they are.

 

Captain_WD. 

[Vitalius]

Dude. @Captain_WD. You da bomb.

Regarding the thing about failure points, I would like to point out that in terms of just "hard drives that could fail", RAID 10 is better than RAID 0 and RAID 1, but worse than RAID 5, 6, and 7. 

In that, in a RAID 1 of two drives, a single drive can fail without data loss. In a RAID 0 of two drives, any failure is all data lost. In a RAID 10 of four drives (a combination of the prior two examples), between one and two drives can fail without data loss depending on which drives they are. 

As the captain mentioned tho, more failure points (software, and hardware beyond the HDDs themselves). So it isn't as straight forward as the above examples but close.

I am personally a fan of RAID 10, but only when done right. But Captain already lists your best options. Just wanted to be informative.

[iamthemoose]

10 hours ago, Captain_WD said:

snip

All is software raid in Disk Management. The data on 6tb is too large to fit on the 4tb.

 

This was especially confusing to me: you need to check if you have the ability to create a RAID1 array without the mirroring part so you can later expand it.

What would a raid 1 array without mirroring be?

 

@vitalius , not looking for a raid 10 or 0 in any way, I want a spanned volume, not striped, that is also raid 1 mirrored.

 

Leaving it as is isn't an option for the current workflow requirements. Sounds like the only way out is to get a new drive, backup, and reformat? No way to span drives without formatting them?

[Captain_WD]

14 hours ago, iamthemoose said:

~snip~

Some motherboards, controllers and software applications allow building a RAID1 array without the second drive where you can add it later on and rebuild the array from the second drive. 

 

You can't really get drives out if the RAID mode and span them without reformatting them with your current configuration. You may be able to combine the volumes to appear as one but technically they will still be two separate RAID arrays. 

 

Captain_WD.