$ man 5 exports
.... nohide This option is based on the option of the same name provided in IRIX NFS. Normally, if a server exports two filesystems one of which is mounted on the other, then the client will have to mount both filesystems explicitly to get access to them. If it just mounts the parent, it will see an empty directory at the place where the other filesystem is mounted. That filesystem is "hidden". Setting the nohide option on a filesystem causes it not to be hidden, and an appropri- ately authorised client will be able to move from the parent to that filesystem without noticing the change. However, some NFS clients do not cope well with this situation as, for instance, it is then possible for two files in the one apparent filesystem to have the same inode number. The nohide option is currently only effective on single host exports. It does not work reliably with netgroup, subnet, or wildcard exports. This option can be very useful in some situations, but it should be used with due care, and only after confirming that the client system copes with the situation effectively. The option can be explicitly disabled with hide.
Why can't it work with a wildcard? :-(
Instead, I tried the ultra-ghetto solution of remounting the nohidden merged filesystem locally (explictly exporting all the filesystems back to 127.0.0.1), and then reexporting that merged mount.... no go. But I'm kinda glad, as that'd be ugly.
So instead do I need each web node to mount every disk? Lame. I'd prefer one per host. I suppose the mounting will be automated anyway (go whitaker!) but I'd rather each web node have 1 mount per storage server rather than 14. (14 logical devices per storage node)
Alternatively, I can have d*w exports per storage node (d == disks, w == webnodes), but that's lame too.
Is there some way to create a merged filesystem (yet with 14 distinct filesystems backing it) which I can then export, without having to futz with nohide?