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I'd like to know if it is possible to mount two different external filesystems via nfs into two directories that overlap.

Do the overlaping directories cause any issues?

/usr/proj/projectA
/usr/proj/projectA/logs
/usr/proj/projectA/data

As an example (/etc/fstab):

192.168.11.111:/vol/DISK1/project-A-bin /usr/proj/projectA nfs
192.168.11.111:/vol/DISK1/project-A-logs /usr/proj/projectA/logs nfs
192.168.11.111:/vol/DISK1/project-A-data /usr/proj/projectA/data nfs
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Based on this snippet it sounds like the answer would be no you cannot do this and still see the files from the initial mount.

Excerpt

NFS filesystems appear to be "normal" filesystems on the client, which means that they can be mounted on any directory on the client. It's possible to mount an NFS filesystem over all or part of another filesystem, since the directories used as mount points appear the same no matter where they actually reside. When you mount a filesystem on top of another one, you obscure whatever is "under" the mount point. NFS clients see the most recent view of the filesystem. These potentially confusing issues will be the foundation for the discussion of NFS naming schemes later in this chapter.

That being said I believe you'd be able to mount logs and data on top of projectA, and only those directories would be obscured, assuming there are logs and data directories within projectA.

Example

Here's a contrived example where I'm mounting 2 NFS shares:

  • mulder:/export/raid1/proj
  • mulder:/export/raid1/packages

Within the same mount point.

$ mount | grep /mnt
mulder:/export/raid1/proj on /mnt/test1 type nfs (rw,addr=192.168.1.1)
mulder:/export/raid1/packages on /mnt/test1/adir type nfs (rw,addr=192.168.1.1)

NOTE: The system, mulder, is the NFS server with the shares.

References

  • In my case the project-A external disk directory does not have logs or data subdir, so if I understood it correctly it won't be a problem ti mount the three external file system, as specified. – Mario Stefanutti Dec 1 '14 at 23:11
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    @MarioStefanutti - correct. I just confirmed that you can mount NFS mounts within other NFS mounts in the manner that you're asking about. It works as I've described. – slm Dec 2 '14 at 0:06

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