When or for what purpose to create a separate file system?

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When or for what purpose to create a separate file system?

Post by engineer » Wed Nov 14, 2012 10:15 am

Now that I have successfully created a 12 GB raidz2 pool in ZEVO CE, and therefore a file system too with the same name, why would I need or want to subdivide that space into more file systems?

Up to now, with the disks small, it had been natural to put my music on a disk (and therefore HFS+ file system, Mac volume), and videos, documents, time machine backups etc on separate disks.

Now with large pools what would be good criteria when to create a new file system?
eg OS+programmes, every single user's home directory, commonly accessed libraries such as music, videos, documents, websites etc? Dependent on change frequency (eg documents vs music)? Or is it easier to put everything in one file system (for a typical home user with small office)? Backups such as TimeMachine in a separate file system?

Experience and recommendations most welcome!
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reasons

Post by grahamperrin » Wed Nov 14, 2012 1:07 pm

You might like part of the pool to be highly compressed, or read only, and so on.

Consider the list of properties that are given when you command
zfs get all
for the file system at the root of your pool.

Another possible reason to create a child file system is given under
disk image approaches to JHFS+ on ZFS
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Re: When or for what purpose to create a separate file syste

Post by ferebee » Wed Nov 14, 2012 4:36 pm

Furthermore, remember that snapshots are granular at the filesystem level.

You might want to keep just a few recent snapshots of your "incoming" data, but many long-term snapshots of your "archive" data. Also, remember that send/receive operate on snapshots, so if you want to send a backup of a particular dataset to a different server, it helps if it lives in its own filesystem.

Creating separate filesystems for directory trees that serve different purposes costs very little, but you can't promote a directory to a filesystem later. (You would need to move it, create a filesystem, and then copy the data over, e. g. with rsync.)

If you want to snapshot a filesystem and all its children, you can always use the "zfs snapshot -r" command.
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