Let's say I have a storage device called A.

I install A into my machine M1 (which contains a drive called B which is a unix boot drive containing the operating system).

I then boot up M1 and mount the drive into some directory.

I read / write to A in M1 for some time.

I then decide that I want to use the storage device A in another machine M2 (which contains a drive called C which is a unix boot drive containing the operating system much like before).

Will I be able to mount A to M2?

I would think so but I don't know all the specifics of UNIX file system management.

If the hypothetical I am giving is too general. Let's say the operating system on both drive C and B is Free BSD.

Also here's a bonus scenario: Let's say C contains ubuntu - is it still possible?


This is certainly possible, and the intended use case for removable media. If your drive B contains a bootable Unix of some sort, it will contain a file tree rooted at /. That is why / is called the "root" directory. The on-disk structure of this file tree is determined by the filesystem in use.

In most cases, each drive (or each partition of each drive) will contain its own file tree; each has its own root directory. 1 When you mount a filesystem you identify its root directory with that of the mount point.

That is, if drive A appears as /dev/sdg, then after mount /dev/sdg /mnt, the /mnt directory points to the root of drive A (assuming your OS supports the filesystem and the mount succeeds). All operations under that directory take place on the filesystem of drive A and are completely independent of the filesystem of your system drive.

1 You can have a single filesystem that actually spreads over multiple independent drives, with e.g. RAID or ZFS, but these drives will then not be mounted individually. They will act as a single unit.


Yes, it is possible. You'll need to ensure both machines support the filesystem you format the drive with.

This is a common, everyday scenario. External HDD, flash media, etc.

  • Okay - The reason I ask this question is because I have read in some places that unix stored the "file directory tree" on only one storage device. So I thought if that one storage device was out of the picture another storage device would not be able to make heads or tails of the data on the mounted drive. – RH_delta Oct 17 '18 at 5:04
  • @user316203 That is why we have virtual file system. – AmeyaVS Oct 17 '18 at 5:08

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