I have several Unraid servers, 1 of which has TV Shows on it. I use Syncthing to sync this folder to a Zyxel Nas 542. This NAS unfortunately has an old Kernel so won’t support Volumes bigger than 16TB! I have upgraded from 4 6TB drives (one by one) to 4 8TB drives, and now have a 16TB volume (well, 15.87 TB) and a 5.78 TB volume.
I have Syncthing syncing /TV Shows/ to the 15.87 TB Volume which is getting full! I would like to be able to Sync some of my TV Shows to Volume 2, but this is a little tricky as it would affect the database of Sonarr / Plex etc. If I split the /TV Shows share. I tried Symlink from Volume 1 to Volume 2, but that didn’t work, as Syncthing doesn’t support Symlinks.
A guy on the Zyxel forum suggests using Binds, but did mention that they don’t get created on a restart, and have to be created manually. This could cause problems if Syncthing starts on the Zyxel Nas before the Binds are re-created!
Is there any easyish way to achieve this? Or will I have to split my /TV Shows share into 2 shares and Sync each to Volume 1 and Volume 2?
Any help or advise would be gratefully appreciated.
Many thanks
It doesn’t follow symlinks but it supports syncing them as symlinks.
That’s what I would have suggested as well. Bind mounts can be added to /etc/fstab or via systemd mount units (on systemd-based systems) for a persistent configuration like any other type of mounting. On systemd-based systems you can also configure ordering between the units so e.g. Syncthing would only be started after the bind mount is active. Maybe the OS from Zyxel is more limited, though.
On my server storing movies I have multiple physical disks and use overlayfs to have them all show up “in one place”. This poses the same configuration “challenge” as using a bind mount.
Another alternative is using some kind of raid so all disks show up as one big disk but this is probably an overkill and even more complicated to configure. (And maybe this would also run into the limit of your kernel.)
If it is really the old version of the (I assume Linux) kernel that is causing this limit it would maybe make sense to update it.
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@Martchus - Thank you for your reply.
My Linux knowledge is limited… 
I do think the Linux version on the Zyxel is also limited. But would you mind giving a couple of examples on how I would configure these binds? and also how I go about getting the bind mounts to activate before Syncthing becomes active?
To my knowledge, I don’t think it is possible to upgrade the Kernel.
Many thanks
Here’s an example for how to create a bind mount in /etc/fstab: fstab - ArchWiki
This is another example from my server showing how to use systemd-specific parameters for dependencies (which of course require a systemd-based system):
/run/media/files3/apps/plex /var/lib/plex none x-systemd.requires=/run/media/files3,x-systemd.automount,bind 0 0
And on the Syncthing systemd unit you would use systemd.unit.
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Thank you very much. I will give that a try.
I really appreciate your help.