Remove inactive volumes to use the disk. Disk #1,2. troubleshooting

I tried a few times and now it detects 1,2 and 4. When switched on it sees 3 too but then it is not "loaded" if this is the right term. I think the initial set up was RAID 5, now I am not sure why 3 and 4 (now  4 is detected) are causing these problems when initially in the logs the drives with faults were 1 and 2. But ideally I would like to try to

1. load 1,2 and 4 in read only if possible
2. do some sort of back up, ie best effort based on what i can load
3.  replace with new drives and restore what saved in previous point.

I have bought 5 drives, 1 i was planning to use as a single external write only backup, ie to restore whatever i can get from this setup
Then use the new drive and restore to current status. 

Is it possible and what other alternatives could you suggest?

Current alert now states "Remove inactive volumes to use the disk. Disk #1,2,4."

bizmate wrote:

In the previous post it looked like disks 3 and 4 were ok but now i dont see them in the volumes sectio

Are all the original disks installed?  The NAS isn't detecting the last two (dmesg, disk-info, etc aren't showing them).

If they are installed, then try powering down the NAS and removing all the trays.  Then re-insert them and power up.

bizmate wrote:

Should I go ahead with the previous instructions given that only the 1st and 2nd drive actually look alive?

The only way that would work is if the NAS detects all the drives in tech support mode.  Possible, but not likely.