ReadyNAS RND4000 - compatable replacement devices

No backup?

We need a bit more info.

Read this guide and let us know exactly what model each of the units are:

http://www.rnasguide.com/2012/01/09/how-to-tell-whether-i-have-a-duo-v1-or-duo-v2-or-nv-v1-or-nv-v2/

unless they are both v1 or both v2 you will not be able to directly migrate your disks.

You should read this: 

https://community.netgear.com/t5/Using-your-ReadyNAS/Service-Action-to-Prevent-PSU-Failures-in-ReadyNAS-NV-NV/td-p/568987

If if you have a NV+ v1 and the unit is within the range specified then you should be able to get a replacement from Netgear.

If not, and the 2 devices you have are not the same then have a few options:

1. You can buy a new Readynas 4 bay model, contact support then follow their instructions to migrate your data.  You will be required to copy the data to another location during this process.  Netgear will likely charge you for this.

2. You can try to find a new PSU.

If your units are the same architecture of course then you can migrate across. There is a specific set of procedures that must be followed when doing this so let us help you with this if the units are indeed the same.