RAID 0 to RAID 1+0 Data Loss?

Do you want me to specifically test this with 8.6.1? Is this APFS or HFS?
Yes it should work and protect your data, but I have not tested this in years and we have changed a lot moving into the new driver technology. Some convert functions were "broken" in this move.

Thanks for your reply. Yes, it would be greatly appreciated if you can test and confirm with 100% certainty if this will work since it's crucial that there's no data loss.

The existing 2-drive RAID 0 volume is HFS but the additional 2 drives to expand into (as RAID1+0) are NTFS. Below are more relevant details if possible. Could you please test and confirm? Thank you in advance!

• SoftRAID version: 8.6.1
• macOS: Tahoe 26.4
• Hardware: OWC ThunderBay 4, 4× 18TB WD Red Pro
• Current state:
  • 2-drive RAID 0 volume, ~36TB, formatted HFS+ (Apple_HFS), contains approximately 9.5TB of data
  • 2-drives NTFS (not yet initialized)
• Goal: Convert to RAID 1+0 by adding 2 initialized drives using Volume → Convert and retain all data on the RAID 0 volume
• Key question: Will existing data on the RAID 0 be preserved during the conversion to RAID 1+0?

@softraid-support But no regression testing? Especially knowing that some things have broken? That is concerning, and does not bode confidence.

Posted by: @mochidust

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I have a 2-drive RAID 0 volume with data on it in SoftRAID 8.6.1 on macOS Tahoe (26.4). I want to convert it to RAID 1+0 by adding 2 new initialized drives using the Convert feature. Will my existing data on the RAID 0 be preserved during this conversion?

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Regardless of any regression testing, the wisest thing when performing such an action should always including performing a backup first. Of course, if all you have are the two new drives and nothing else, that will not be possible. You will need another drive, at least temporarily, unless the drive sizes are different. Then you could also consider creating a partition on the larger drives to use for backup, if there is enough space.

 

 

If the starting point is a RAID 0, would this conversion not produce a 0+1 set-up rather than a 1+0?

@mochidust 
Yes, I just tested it and it worked fine. I tested also on APFS, the harder use case.
I did not remember if it "failed" to add the disks, or worked, in no case is data lost.
anyway, the converted RAID 1+0 volume has the original data and is happily running a read/write script.

@smayer97 
Agree! always update your backups when doing anything that "could" risk your data.
I ran the tests, as it was not a test I had run in a while. But others had.

@smayer97 
By definition, RAID 1+0, is a set of Mirrored RAID 0 disks. Its confusing, yes.

@softraid-support According to here, and other sources: https://www.thegeekstuff.com/2011/10/raid10-vs-raid01/

a RAID 1+0 is a stripe of mirrored drives, and a RAID 0+1 a mirror of striped drives, opposite to what you are saying. 

So, was does SoftRAID implement?

@smayer97 

Thank you for the correction and the reference. You are right that the notation is the opposite of what I stated — RAID 1+0 is indeed a stripe of mirrors, and RAID 0+1 is a mirror of stripes.

SoftRAID's RAID 1+0 implementation pairs drives as mirrors and stripes across those pairs, but I had the shorthand notation backwards. I appreciate the correction. (the confusion on my end was because we can convert to a RAID 1+0 starting with RAID 0, not RAID 1)

As for why SoftRAID can convert a RAID 0 to RAID 1+0? it's because a RAID 0 stripe already exists as the top layer.
Converting to RAID 1+0 adds a mirror partner to each drive in the existing stripe, so the stripe layout never changes and no data needs to move.
It's an additive operation rather than a destructive reorganization of data on disk, which makes the conversion process straightforward.

So I understand, would the end result of converting a RAID 0 to RAID 1+0 be that the original drives 1 & 2 would end up in separate groups, such that group 1 would consist of drive 1 and 3 (mirrored) and group 2 would consist of drives 2 & 4 (mirrored)? 

Also, while on this topic, does SoftRAID have the ability to convert a RAID 1 to a RAID 0, with the addition of at least 2 new drives, e.g. taking drives 1 & 2 and creating a RAID 0 with drives 3 & 4?

@smayer97 
No, we only support RAID 1+0 one way and do not support any conversion that requires moving data around the disks. (Like converting 0 to 1, 1 to 0, RAID 0 to RAID 5, etc.)

@smayer97 
Yes, each drive would get a Mirror disk "behind" it.