4 drive raid 5 to larger 3 drive raid 5 possible?

[njhorn]

I currently have a maxed out 4 drive RAID 5 on a 3204t with 4TB drives, for a 12TB RAID 5... I have 3 10TB drives I want to replace with for a 20TB RAID 5, and then plan to use the empty fourth slot for an SSD cache or maybe another 10TB drive for backups in a single drive setup... Is there any easy way to go about this? I 99% sure impossible to go from a 4 drive array to a 3 drive array even with larger drives, so the only thing I can think of is to backup all data to an external 10TB drive (I have about 9.5TB of data right now), then pull all the drives and install new ones and create a new array and copy data back... But then I lose asustor settings, docker containers I have running (although I can back up the data directory and configs), etc, making it an all around pain in the ass... Any ideas?

[orion]

You just gave yourself the answer. Backup is the only way that I know.

[njhorn]

You just gave yourself the answer. Backup is the only way that I know.

damn, ok... other option I came up with is to:
1) Backup to an external HD
2) pull drive 1 and break the RAID 5
3) Insert a 10TB drive and set up as JBOD
4) Clone the RAID contents over to the new drive 1
5) Pull the remaining drives
6) Insert new drive 2 and 3
7) Expand the single drive 1 to a 3 drive RAID 5

My question there though is how does the OS migrate over? Or is that the fault in my thinking? I think I just need to bite the bullet, backup and pull the drives, and try setting up the new array cleanly with a new OS, and copy back over the data and docker containers and such... I guess the benefit of that is I still have the original array intact (although out of the unit) and can reinsert those drives to go back to my original config if I have issues...

I'm seriously considering just buying a newer asustor unit as another option and setting up clean on that, and then selling my 3204t and 4 x 4 TB red drives also

[father.mande]

Hi,

I think that point 3 is false (as I know)
... when you enter the new disk in the slot of the pulled disk ... automatically the Raid5 rebuild mechanism is started, so YOU CAN'T change at this point ...

So the solution is to backup the data on an external disk then rebuild WITH OTHERS disks a new Raid5, reconnected the external disk and copy back the data.

You can't use the external disk as an internal disk ... because A.D.M. reformat the disk when pushed internally.

The only solution, I used in the past on another Brand (so no idea if possible with an Asustor) ... only for "stupid" people like me ...
... power off NAS
... pull all the internal disks (keep the order)
... enter one disk, power on, and initialize the NAS with this new disk (formatted and installed) as a single for ex. (even single is a Raid1 without mirror in ADM)
... power off
... reintroduce the Raid5 disk (at the good place) and restart the NAS (normally all start as usual)
... connect the new disk formatted in an USB box, mount the partition 4 (eventually do a mdadm and mount md before if need due to special single mode (Raid1))
... save your data (structure exist with default share) to the external disk
... power off
... pull the 4 Raid5 disks, reintroduce the external disk, start A.D.M. and pray that A.D.M. accept the disk as a "Asustor formatted" disk ... so without cleaning the data and partition.

BUT as I write here before ... I never test this solution on an Asustor NAS ... so it's theoretically, in all case if at last point you don't format again the disk ... you have created a backup ... and in all case your Raid5 (old disks) is still available.

Lot of problem can exist during this and can need some corrections ... so a full backup then a full re-initialization with new disks is perhaps the best way.
I am a little dangerous but only with my own NAS ... so take all the time to build your own solution.

Philippe.