Linux – Mount two nfs’s shares from different storage over the same directory on linux

clusterlinuxmountnfs

I have a set of 4 Linux web servers on cluster all of them have the same mount point:

/folder

This /folder is a NFS mount share over a NAS but is full and no more luns/disk are available to expand the NFS. I have another NAS with enough space to solve the problem, but a software developed in house search for JPG files over the /folder. I want to know if is possible to mount another NFS share from the other NAS to the same directory to have more space? No matter that the new path to write files is /folder/newshare.

Best Answer

What you want do do can be achieved precisely with overlayfs. With it you can take your /full dir and another /notfull dir and mount them at /third-dir.

Reads will seek through the /notfull into the /full and writes will go to a third dir.

Have a look at the docs, remount the full dir away from the target name and then use overlayfs to recreate the intended target.

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Linux – NFS: force file mode/mask on mount

My understanding is that NFS works off of whatever file system permissions are set on the server's file system. You should be able modify these by issuing a chmod on either the client, or the server (although I don't know if you have access to the command line on the QNAP device).

With regards to the noexec option, that simply prohibits executable files from being ran on that file system... it doesn't prevent you from setting the execute bit in the files permissions.

Hope this helps!

Linux: same device mounted on differences mount points

/etc/mtab is showing the result of using bind mounts, is my guess. You can bind mount any directory, and I suspect you are seeing the result of that.

$ mkdir test/ /tmp/test
$ sudo mount --bind test/ /tmp/test
$ cat /proc/mounts
<..snip...>
/dev/root /tmp/test ext4 rw,noatime,data=ordered 0 0

This question provides a more in-depth explanation/example: https://unix.stackexchange.com/questions/128471/determine-what-device-a-directory-is-located-on

df -h is not showing these because bind mounts are 'dummy' filesystems, and df requires -a to show those.

Best Answer

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Linux: same device mounted on differences mount points

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