Is it possible to configure RAID 1 for more than 2 disks?
That is to effectively have a single disk with 3 copies.
This is inefficient I know but require multiple redundancy over space.
Second ...
Can any disk then be removed and stored as a backup and be readable as required without using a readynas (assuming some caddy or other and s/w to interpret the linux file system etc)?
Thanks
Model: RN424| ReadyNAS 424 4-Bay with up to 40 TB total storage
Is it possible to configure RAID 1 for more than 2 disks?
No. The OS partition does use RAID-1 across all 4 disks, but Netgear doesn't allow this with the NAS data volume. Some customers have asked for it, it would be nice if Netgear added support for it in FlexRaid.
You can use RAID-6 though, which gives you better RAID protection than normal XRAID.
Can any disk then be removed and stored as a backup and be readable as required without using a readynas
Not really. The volume is marked as degraded, and installing a replacement disk to freshen the backup requires a resync - which is time consuming. One other concern is that the SATA connectors on internal drives aren't really designed for repeated pulls/insertions.
A jbod volume can be read w/o a ReadyNAS but does require a linux PC (since windows and mac don't support the BTRFS file system). But even there, the web ui isn't structured for this use case.
Better solutions for backup that you might consider are to use
USB drives directly connected to the NAS or a PC
a second NAS for backup (either on site or off)
cloud backup for disaster recovery
Keeping the backup on a completely separate device is safer than RAID (even multiple disk mirroring).
