[Areca] Shrinking Raid 1 array

[ladegro]

Hi all,

I'm new to the forum so bear with me if I'm breaking any ground rules. This looked like the right place for my question though....

My linux server is run with an Areca 1220 PCI-X raid card. All eight slots are taken, 4 drives form a raid-5 array (1TB each), 3 drives form a raid-1+0 array (250GB each) and one drive is pass-through (2TB).
The OS is run from the raid-1 array.

Now, I have an urgent storage need. My idea is that the raid-1 array can do with just two drives just fine. That would give me the option to plug in an extra 2TB drive I have laying around as passthrough.
When I pull the 3rd 250GB drive, the array becomes degraded as expected, but besides that, runs just fine.

However, I'd like the array-state to be set to normal / aka have the array be rebuilt over just two drives without data loss.

I've searched around, but can't find this question on any forums. I e-mailed Areca and they reply the following:

Dear Sir/Madam,

data layout between 3 drives array and 2 drives array are different.
for your case, if you create a new array with 2 drives only, data inside are inaccessible.


Best Regards,

But with raid-1, data is just duplicated over all drives right? So I'm not sure about this answer. I've read methods using the RESETCAPACITY command, but that doesn't seem to work?

Anyone with good ideas? Thanks in advance.

 

[ladegro]

Am I asking an impossible question or simple giving not enough information for someone to help me?

 

[ezno_matrix]

Why not use mdadm on your Linux box? It offers a lot more flexibility over the RAID card you are using.

For your current challenge, you will need to completely destroy the RAID1 array and have it recreated with 2x250GB drives.
1. Backup your OS drive on the RAID1 array to the 2TB drive you have laying around. This is simple on Linux as you can copy to files using the copy command of your choice.
2. Remove 1 of the 250GB disk from the RAID card.
3. Boot to the RAID card BIOS and destroy/recreate the RAID1 with 2x250GB disks.
4. Boot from a recovery disk/usb and format/restore the data to the RAID1 array.
5. Configure your boot loader.
6. Boot a test the system.
7. Connect the additional 2TB disk to the RAID card and use as you wish.

 

[ladegro]

Thank you very much. I had hoped not to have to do all this but looks like I'm unlucky...