RAID 10 Question - Onboard Controller and How to Break

[davidst95]

Hi, I posted a question on a RAID 5 setup a few days ago. I'm not sure if I should start a new thread for a question about RAID 10. If I wasn't suppose to I apologize in advance.

 

I have two WDC 4TB Black hard drives.   I got a good deal on 2 more drives of the same type.   I would like to create a RAID 10 setup.   I have a Gigabyte Gaming GT Z97 motherboard that has a Intel Raid Controller that supports RAID 0/1/5/10.    Is it possible to break a RAID 10 to non raid volumes?     If not, should I use Windows Disk Manager to create a software RAID?  

 

Also, would it make sense to purchase a seperate PCIe RAID controller?   These drives will not have the OS on it.   Thanks for any info.

 

David

[ChineseChef]

When you say break the raid, I assume you are meaning converting it from 1 logical disk back to 4 logical disks (1 per physical) while keeping all data intact?  simple answer is no.

 

As soon as you start striping data, you don't have complete files on any 1 disk.  Thus the disks have to stay together, this doesn't matter if it is software or hardware raid.

 

There are ways to treat multiple disks as 1 logical disk, but this method simply writes whole files to 1 of the drives.  The files are written to the drives based on however you configure it; such as writing new files to the drive with the most free space, or keeping files within folders together on the same drive as much as possible.

This method does not give you the speed or the protection of raid 10 though, it is simply drive pooling.

 

Except in very special cases, consider raid as a whole solution.  You have to create it before you put data onto it, and have to remove data before you change it.  Higher end raid cards allow for expansion of existing raid volumes, and some even offer conversion between array types.  But for consumer grade parts, you will usually have to have a secondary place to store the data while you change the array.

[davidst95]

Thanks for the reply.    I thought RAID 10 has two mirror disks and two strip disks.   Couldn't I "break" the RAID and used one of the mirror disks?   Thanks.

 

David

[ChineseChef]

Thanks for the reply.    I thought RAID 10 has two mirror disks and two strip disks.   Couldn't I "break" the RAID and used one of the mirror disks?   Thanks.

 

David

 

Sort of, raid 10 works by striping the data across 2+ drives, it then mirrors the data on to another set of striped disks.  So, you could separate the pair of striped disks, but you have to keep each set together, and it will only be readable by the same exact type of controller, and will likely have to be "repaired" or run in a "degraded" state.  Which your controller may have difficulties with. 

 

For all intents and purposes, consider breaking apart any type of striped raid (0/5/6/10) to be equal to destroying the data on the array.

[brandishwar]

RAID 10 is RAID 0 striped across two RAID 1 arrays, @ChineseChef. What you're describing is RAID 0+1.

 

Back to @davist95, no you cannot do that with a RAID 10. The only RAID for which you can do that is RAID 1, but that's only because it's a straight mirror. You might be able to do it with RAID 0+1 (RAID 01), but that'll depend on controller implementation.

[ChineseChef]

RAID 10 is RAID 0 striped across two RAID 1 arrays, @ChineseChef. What you're describing is RAID 0+1.

 

Back to @davist95, no you cannot do that with a RAID 10. The only RAID for which you can do that is RAID 1, but that's only because it's a straight mirror. You might be able to do it with RAID 0+1 (RAID 01), but that'll depend on controller implementation.

 

I had never bothered to learn the difference (just did some heavy reading on it), since they are identical in outcome and performance.  That and I have never seen a raid card that offered 0+1, its only always been raid 10 on the controllers I was working with.  Thanks for the correction.

[brandishwar]

I had never bothered to learn the difference (just did some heavy reading on it), since they are identical in outcome and performance.  That and I have never seen a raid card that offered 0+1, its only always been raid 10 on the controllers I was working with.  Thanks for the correction.

 

Fault tolerance with RAID 10 (aka RAID 1 + 0) is greater than RAID 0+1, which is why it fell out of favor and why you almost never see it anywhere anymore. Given the choice between RAID 01 (0+1) AND RAID 10, the latter is the better option.