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 <[email protected]>: > 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 > <[email protected]> >
