Installer changes on master (does not effect release)
kusumi.tomohiro at gmail.com
Tue Dec 15 05:53:43 PST 2015
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
> Previously the installer used radically different arrangements for UFS
> vs HAMMER. UFS put an integrated boot+root on partition 'a', swap on
> and HAMMER put boot on 'a', swap on 'b', and root on 'd'. HAMMER
> 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
> making it relatively easy for the user to manage later on if/when
> 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.
> Matthew Dillon
> <dillon at backplane.com>
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