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long technobable about early Unix filesystem partitioning
(I posted this to my mastodon account then realized that it should be here since it's long-form.)
The discussion of historical Unix file system layout recently came up in a chat so I thought I'd share it here as well. I started in 1985, so can't speak to what came earlier than that. This is based on memory so should not be considered authoritative.
In BSD 4.2 we had / (aka 'root), SWAP, /tmp, /usr, /usr/local (optional, perhaps), and some place for user home directories like /users or /homes. (Or, if you were broken, /mnt). If you had multiple drives user homes frequently went on one of them instead.
There were binaries in /etc (ifconfig being the main one I remember, might also have been shells), as well as /bin & /sbin (which were on /) and /usr/bin & /usr/sbin. /sbin was for things like fsck(8) which weren't for "ordinary users".
On-disk layout was usually something like /, SWAP, /usr, ... The idea was to make / and SWAP as fast as possible (they were on the speediest part of the disk) then put the rest where it could be useful.
There were fun things like /usr/tmp and /usr/log that were writable, so just about every filesystem on the host was RW.
We kept /tmp separate so it couldn't fill / and break things. Likewise /usr was separate because of /usr/tmp and /usr/log having the potential to fill up and break things.
The big thing: disks were small, expensive, and slow so the stuff in / was *just enough* to boot the host. /sbin and /bin had important binaries you'd need to start the system and fix things if mounts failed (e.g. fsck(8)) but nothing else - that all went into /usr/bin.
Eventually Sun wanted to do the "diskless node" thing so they created /var and moved all the writable filesystems out of /usr which could then be common to all hosts.
Over time, as disks got cheaper and larger, someone moved everything out of /bin into /usr/bin, leaving a link behind for us Old Farts.
Then someone else didn't like the idea of /usr/local so created /opt (I think that's Sun's fault as well but won't swear to it).
So we wound up with /, SWAP, /usr (later /usr just became part of /), /var, /homes-type-filesystem, /tmp, /opt, and optional filesystems like /usr/local.
I hope this top-of-the-head recollection was sufficiently understandable and at least slightly interesting.
The discussion of historical Unix file system layout recently came up in a chat so I thought I'd share it here as well. I started in 1985, so can't speak to what came earlier than that. This is based on memory so should not be considered authoritative.
In BSD 4.2 we had / (aka 'root), SWAP, /tmp, /usr, /usr/local (optional, perhaps), and some place for user home directories like /users or /homes. (Or, if you were broken, /mnt). If you had multiple drives user homes frequently went on one of them instead.
There were binaries in /etc (ifconfig being the main one I remember, might also have been shells), as well as /bin & /sbin (which were on /) and /usr/bin & /usr/sbin. /sbin was for things like fsck(8) which weren't for "ordinary users".
On-disk layout was usually something like /, SWAP, /usr, ... The idea was to make / and SWAP as fast as possible (they were on the speediest part of the disk) then put the rest where it could be useful.
There were fun things like /usr/tmp and /usr/log that were writable, so just about every filesystem on the host was RW.
We kept /tmp separate so it couldn't fill / and break things. Likewise /usr was separate because of /usr/tmp and /usr/log having the potential to fill up and break things.
The big thing: disks were small, expensive, and slow so the stuff in / was *just enough* to boot the host. /sbin and /bin had important binaries you'd need to start the system and fix things if mounts failed (e.g. fsck(8)) but nothing else - that all went into /usr/bin.
Eventually Sun wanted to do the "diskless node" thing so they created /var and moved all the writable filesystems out of /usr which could then be common to all hosts.
Over time, as disks got cheaper and larger, someone moved everything out of /bin into /usr/bin, leaving a link behind for us Old Farts.
Then someone else didn't like the idea of /usr/local so created /opt (I think that's Sun's fault as well but won't swear to it).
So we wound up with /, SWAP, /usr (later /usr just became part of /), /var, /homes-type-filesystem, /tmp, /opt, and optional filesystems like /usr/local.
I hope this top-of-the-head recollection was sufficiently understandable and at least slightly interesting.