Changing configuration of the Array (without losing data)

[Pducharme]

Hi all !

 

I'm about to do a major change to my Unraid server. 

 

Currently, I have a Lian-Li Full tower (PC-A77) with 4 of the iStarUSA BPN-DE350SS-RED (5-in-3).  My array currently consist of disk1 to disk18 (but disk15 doesn't exist (?)) and I have Parity1 and Parity2.  My Cache device is a Corsair MP600 1TB PCIe Gen4 NVMe storage.

 

I bought a Supermicro CSE-836 SuperChassis (empty) with a SAS2 backplane (SATA3 compatible) and dual SuperQuiet 920W Platinum PSUs.  This case allow me to only have 16 disks in the bays and couple of 2.5in inside the server chassis if I want.  So, in total, I would be able to put 2 x parity and only 14 data disks.  I will have to eliminate 3 disks from my array so they server is fully populated. 

 

My Disk Usage is only at 64% right now and most of my disks are 8TB, with 2 x 5TB and 2 x 6TB.   I also have another 8TB not currently in the server that can replace one of the 6TB. 

 

So, i want to remove my 2 x 5TB and 1 x 6TB (and later, replace the other 6TB by my 8TB I have laying around, but I'll do that after).

 

If I move out all data from those 3 disks to other disks that have enough free space, how can I re-arrange the Array so I can have disk1 to disk14 as data disks with my 2 x parity.   I don't mind running a new Parity Sync after the process, but If it can be avoid, that would be even better.

 

Also, another challenge is that with the new case, i'll have a backplane with only 2 cables going to 1 of my LSI SAS2008-based PCIe Card.  My other LSI SAS2008 won't be required anymore.   Does the fact that I switch to a backplane will also add complexity to my data disk re-arrange process ?  I mean, they won't be recognized in the same order for sure... 

 

Thanks to the guru of storage that can help me on this

[JonathanM]

16 minutes ago, Pducharme said:

If I move out all data from those 3 disks to other disks that have enough free space, how can I re-arrange the Array so I can have disk1 to disk14 as data disks with my 2 x parity.   I don't mind running a new Parity Sync after the process, but If it can be avoid, that would be even better.

The disk in parity slot 1 remains valid IF the drives you remove are overwritten fully with zeroes. The disk in parity slot 2 would have to be rebuilt regardless.

 

Given the time and risk involved in overwriting an array drive with all zeroes, I'd be inclined to just bite the bullet and rebuild parity.

[Pducharme]

Ok. Thanks!

 

What about my other questions? any idea about that ?  Can I just empty the disk i want to remove, then stop the server, reinstall my motherboard/cpu/ram/hba in my new case, connect everything, and let it detect the disks and Unraid will choose where are disk1 or disk3 and stay OK ?

 

do I need to do a new Config ?  I just don't want to loose the data, I don't have a full backup due to the size... 

[JonathanM]

Unraid identifies disks by serial number, so as long as the controller passes the disk through unmolested unraid will just assign them back in the same logical slots, and if you remove the disks, unraid will see that you have more missing disks than you have parity disks, and not start. If you have 2 parity disks and remove 2 disks, unraid will emulate their content so you can replace the disks.

 

To change the logical slot numbers for your disks, you will need to do a new config. If you select the option to keep all assignments, when you go to the main GUI tab all the disks you transferred over will still be assigned to their original slot numbers, and you can rearrange however you want. The only disks that will be overwritten are the parity slots, so just don't accidentally assign a data disk to a parity slot and you should be fine. Do NOT select the parity is valid option, because it isn't.