Is the ReadyNAS 214 still for sale?

A second NAS is also a great way to provide backup of your data.

Many models have dried up in the market.  StephenB has speculated it's a COVID-19 thing, and I tend to agree, but Netgear has not confirmed.  Could be reduced work force or use of available workforce, parts, or transportation for more critical items.  With many moving to work from home situations, there may have also been a run on available units.  If this is the case, it could also delay Netgear's ability to do a warranty replacement.

Any 4 or more bay ReadyNAS running OS6, including a converted legacy one (only some can be converted, don't buy untill you verify it can be done), can accept your volume and use it.  But most of them are either hard to find or also priced very high right now.  The rack mount units do seem to still be available at their normal price, but they can get quite noisy because of the small fans.

If you choose an Intel based unit as your spare, be aware that any apps you have installed will have to be re-installed.  It's best if you un-install on the ARM unit before migrating the volume, then re-install on the new NAS.