The Views Expressed Below Do not in any way reflect Internal Doctorine or Official Statements of Netgear Inc. These are just my notes - Use at your own Risk.
THIS ARTCILE APPLIES TO READYNAS 4.2.x INTEL UNITS and 4.1.x SPARC UNITS and 5.x HOME ARM UNITS
NETGEAR READYNAS UPGRADE PROCEDURES
How to tell what architecture - look at firmware number of RAIDiator:
1.x.x = READYDATA
3.x.x = OLD SPARC (end of life)
4.1.x = NEW SPARC (end of life, can go from OLD SPARC to NEW SPARC)
4.2.x = INTEL (end of life)
5.x.x = ARM (home units)
There are two options for firmware updates. Local or Remote. Local is what I go with all the time, its a manually update. You download the file and let the READYNAS have it and update it self. Remote is just an automatic internet update - I dont use it because it doesnt jump the NAS the way I like it in firmware 4.2.15
INTEL UNITS (RAIDiator 4.2.x):
HOW TO UPDATE:
If your firmware is at 4.2.1 to 4.2.14 Upgrade to 4.2.15 first then to 4.2.17 then to 4.2.22
If your firmware is at 4.2.15 go to 4.2.17 then to 4.2.22
If your at 4.2.16 or above then upgrade straight up to 4.2.22
Ex: 4.2.1 -> 4.2.15 -> 4.2.17 -> 4.2.22
Ex: 4.2.15 -> 4.2.17 -> 4.2.22
Ex: 4.2.16 -> 4.2.22
Ex: 4.2.14-> 4.2.15 -> 4.2.17 -> 4.2.22 (SOME MIGHT SAY THESE JUMPS ARE UNNESSARY HOWEVER I LIKE THE CONVERSION FROM MBR TO GPT GO VERY SMOOTHLY)
WHY THE JUMPS?:
Because at 4.2.15 the NAS used MBR partition tables ( max supported size drive is 2 TB) and with 4.2.16 onward the partitioning tables of the disks were converted to GPT allowing disk sizes of much larger size (disk sizes so big they are not produced yet in the market)
STEPS TO UPDATE:
(0) Understand how many updates you need to do by reading "HOW TO UPDATE" above and also have the firmware downloaded
(1) Go to Frontview https://<ip of nas>/admin (if you dont know IP open up the software RAIDAR and hit RESCAN to see your NAS - can get RAIDAR from www.readynas.com)
(2) Go to Update -> Local
(3) Browse for the Firmware
(4) Hit Okay, Keep hitting okay and "Perform System Update"
(5) It will take you to the SHUTDOWN tab and ask you to REBOOT the Unit. There will be some checkboxes make sure you select the following options:
() Shutdown and turn off device.
(X) Shutdown and reboot device.
 Perform volume scan on next boot. This process can take several minutes to more than an hour depending on disk capacity and volume content.
 Check and fix quotas on next boot. This process can take several minutes to more than an hour depending on disk capacity and the number of files
Only Check the 2nd circle so it only does a reboot, do not check any of the scan/fix quotas checkboxes so that it doesnt take forever during the update process.
(6) You can follow the update in RAIDar. By hitting Rescan. It takes about 10 minutes or less.
(7) If you need to do more updates then repeat from step 1.
(8) If your coming from a very old firmware like 4.2.1 for example and you update all the way to 4.2.22 and you get stuff acting weird just do an OS Reinstall by going to the bootmenu: http://www.kossboss.com/rnasbootmenu
OLD SPARC UNITS (3.x.x):
Uses MBR so max supported disk size is 2 TB
* Upgrade to NEW SPARC - same instructions as NEW SPARC
* Have a backup of data since the big jump might cause issues
* OS Reinstall after upgrade using the boot menu http://www.kossboss.com/rnasbootmenu
NEW SPARC UNITS (4.1.x):
Uses MBR partitioning table so max supported disk size is 2 TB
No plans for GPT upgrade
* Download the latest firmware from www.readynas.com (4.1.10) and your readynas go to frontview. System->Update->Local
ARM UNIT (5.x.x):
* Not my area of expertise, But just download the latest firmware and do the local update. Use the manual if you can not figure out how to locally upload firmware.
* Follow the release notes and manual for the update.