I've had my Readynas104 for a little while now and have been using a 5TB WD NAS HDD as my primary drive with a 4 TB one sitting as a spare. I've been for the longest time meaning to setup mirroring so that I have a backup of everything on my primary drive and finally have some time to look for a 5 TB drive that I can use to mirror the primary one. I'm finding out that WD doesn't make the 5 TB anymore and if I do want one it'll cost $100 more than a 6 TB one. Well anyway can I buy the cheaper 6 TB drive and mirror the contents of the 5 TB drive knowing that I'll be giving up 1 TB on the 6 TB one? If so, how do I set this all up without erasing the contents of the primary drive? Thanks in advance!
If so, how do I set this all up without erasing the contents of the primary drive?
Check that XRAID is enabled on the volume page of the web-ui. It's enabled if there is a green stripe on the XRAID control. If it's disabled, just click on the control.
After that you just hot-insert the new disk (unformatted) into the NAS. It will automatically switch your volume from JBOD to RAID-1 and begin mirroring the existing disk. Performance will be sluggish until that completes.
I've been for the longest time meaning to setup mirroring so that I have a backup of everything on my primary drive
This is a good idea, but it's not the same as a true backup. RAID is not enough to keep your data safe - there are quite a few failure modes where you can lose all your data. If you aren't backing up the NAS to a different device, then I recommend also putting a backup plan in place (for instance backing up the data to a USB drive).
