Quite a while ago, one of the 6TB (alleged Red) drives in my 24TB PR4100 had a catastrophic mechanical failure. Since my RAID setup is JBOD, I lost a fair amount of data (cooking shows and cartoons, not a major loss). Now I’m debating whether to upgrade to a larger NAS (WD 32TB), or just install a larger (12TB) drive in place of the failed one. My main question is, can the latter be done without affecting anything else? I have to imagine since I’m running JBOD I should be able to.
Of course on the other hand, if I buy a larger NAS and run say RAID 5, I could transfer my existing data over and not worry so much about a loss should another drive fail.
If you are using JBOD; you don’t need to match drives in the PR4100. 3 x 6TB with 1 x 12TB is fine in JBOD mode.
Note: Raid is not foolproof backup. It protects against HDD failure; but not Firmware FUBAR; user error or FIRE.
Depends entirely if you want a second NAS in your system 
Because you KNOW if you buy a nice new Synology; you WILL buy a drive for the PR4100
I appreciate the reply. Not sure about another brand, as I’ve got the PR4100 and an EX4100 now and other than the one drive failure, everything else has been good. I’ll keep looking around and if I can find the right deal, I’ll probably buy another PR4100 but this time a 32TB. I’ll switch the EX to a backup NAS and use the other PR as a 2nd back up and as my Logitech Media Server (both are still on OS3, I won’t “upgrade” to OS5).
I share your reluctance to use OS5. (I gave up on it over a year ago).
An I reading this right? you have two functioning 4 bay NAS units and are considering to buy a third?
Yeesh. That’s some data storage requirement 
Is your plan to run the new unit on OS3 or OS5? Buying a NAS in 2022 with the intention of running OS/3 is . . . . . not appropriate. You should think twice about having OS3 on any network unless internet access to the device is blocked at the router (My OS3 boxes reside on a dedicated router with no internet access at all)
Also - - - if you are buying a new unit. . .I am not so sure it won’t come with OS5 installed. Rolling back requires. . . a copy of OS3 firmware AND using SSH to wipe config files and the OS files.
The other brand is mentioned as an example of a competitor that offers a far better software solution than what WD offers. The hardware is a bit more expensive. . .in part driven by hardware differences.
I’ve got 3 NAS devices right now, a 4th is on the way. I’ll update the latest PR4100 one to OS5 and run Emby on it, my current PR4100 will remain on OS3 so I can keep using LMS. My EX4100 will become my new archive and the old Netgear goes to the recycler. And external/remote access has always been turned off
turning off external / remote access. . .
. . .from the router?
. . or from the NAS? If you are doing it from the NAS - - -there will still be internet vulnerabilities present.
