Installer changes on master (does not effect release)

[Tomohiro Kusumi]

I think what makes PFS difficult to understand is the way nresolve finds
PFS by checking two consecutive '@' within the name (followed by
master/slave:PFS#), and then look for the root inode of that localization.

This gets a bit nasty when there are more than 1 hammer mounted, and each
hammer has a PFS with the same PFS#.
For example, the same "@@-1:00001" string indicates different PFSes
depending on which hammer you are at, but anywhere in that hammer.

You could pfs-destroy "@@-1:00001" even if you don't see "@@-1:00001" in
the current directory, because all it cares about is two consecutive '@'
somewhere in the hammer you're currently at.
This is weird from the way filesystems usually behave.



2015-12-15 4:53 GMT+09:00 Matthew Dillon <dillon at apollo.backplane.com>:

>     Master has gotten an installer revamp w/regards to the partition
>     setup.
>
>     Previously the installer used radically different arrangements for UFS
>     vs HAMMER.  UFS put an integrated boot+root on partition 'a', swap on
> 'b',
>     and HAMMER put boot on 'a', swap on 'b', and root on 'd'.  HAMMER
> installs
>     also created a whole bunch of PFS's for various major directories such
>     as /home.
>
>     The new setup is more uniform.  An 'a' boot, 'b' swap, 'd' root, and
>     'e' /build is created whether UFS or HAMMER is chosen.  PFS's are no
>     longer used.  Instead, major directories which generally do not have
>     to be backed up (such as /usr/obj) are put on /build and null-mounted
>     to their appropriate places via the fstab.  Major directories which
>     typically do need to be backed up, such as (most of /var), /home, /usr,
>     and /usr/local remain on the root filesystem.
>
>     The new setup handles small drives (typically < 40GB) by not creating
>     a separate /build partition.  It still creates the /build directory
>     infrastructure on the root filesystem and still creates the
> null-mounts,
>     making it relatively easy for the user to manage later on if/when
> moving
>     to a setup with more storage.
>
>     --
>
>     I've been using this scheme very successfully at home and on servers
>     for more than a year now and really like the flexibility and ease of
>     management.  The null mounts are a lot easier for users to manage than
>     the hammer PFS's, and the separation reduces the chances of the root
>     filesystem becoming corrupt during a crash.
>
>     These changes also allow UFS installs to use encrypted roots which they
>     could not before.  While we recommend HAMMER over UFS generally, there
>     are still a few cases where UFS is more convenient, such as on small
>     storage media / USB flash drives.
>
>                                         -Matt
>                                         Matthew Dillon
>                                         <dillon at backplane.com>
>
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