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Annotation of wikisrc/zfs.mdwn, revision 1.5

1.1       gdt         1: # ZFS on NetBSD
                      2: 
                      3: This page attempts to do two things: provide enough orientatino and
                      4: pointers to standard ZFS documentation for NetBSD users who are new to
                      5: ZFS, and to to describe NetBSD-specific ZFS information.  It is
                      6: emphatically not a tutorial or an introduction to ZFS.
                      7: 
                      8: Many things are marked with \todo because they need a better
                      9: explanation, and some have question marks, indicating that the
                     10: statement needs verification.
                     11: 
                     12: # Documentation Pointers
                     13: 
                     14: See the man pages for zfs(8) and zpool(8).
                     15: 
1.4       gdt        16:   - [Oracle ZFS Administration Manual](https://docs.oracle.com/cd/E26505_01/html/E37384/index.html)
                     17:   - [FreeBSD Handbook ZFS Chapter](https://www.freebsd.org/doc/handbook/zfs.html)
1.1       gdt        18: 
                     19: # Status of ZFS in NetBSD
                     20: 
                     21: NetBSD has imported OpenZFS.  \todo versions, links
                     22: 
                     23: ## NetBSD 8 and earlier
                     24: 
                     25: While there is some ZFS code, it is old, and seems to have significant
                     26: problems.  If one wants to use ZFS, first upgrade to NetBSD 9.  It is
                     27: unlikely that anyone is interested in helping, other than telling you
                     28: to upgrade to 9.
                     29: 
                     30: (Reports of how well NetBDS 8 works are welcome on netbsd-users, if it
                     31: can actually be recommended for use.)
                     32: 
                     33: ## NetBSD 9
                     34: 
                     35: There have been fixes since 9.0 RELEASE.  It is best to upgrade along
                     36: the netbsd-9 branch, but the release should be ok.
                     37: 
                     38: \todo This is OpenZFS as of X.   Most aspects work solidly.
                     39: 
                     40: \todo This supports pool version 28/5000 (really true?).  Of the
                     41: feature flags found in modern OpenZFS, \todo are supported.
                     42: 
1.5     ! gdt        43: Generlly, fixes to ZFS in current will be pulled up to 9, but new
        !            44: features typically will not be.
        !            45: 
1.1       gdt        46: ## NetBSD current
                     47: 
1.5     ! gdt        48: The ZFS code in current is very similar to that in 9.
        !            49: 
        !            50: There is initial support for [[RootOnZFS|ZFS root]], via booting from
        !            51: ffs and pivoting.
1.1       gdt        52: 
                     53: One can make a ccd using a zvol as a component.  This allows reading a
                     54: GPT label from the zvol, which is useful in case the zvol had been
                     55: exported via iscsi and some other system created a label.
                     56: 
                     57: ## things that aren't suported yet
                     58: 
                     59: \todo (?) hotswap
                     60: 
                     61: \todo (?) direct boot into zfs root
                     62: 
                     63: ## Architectures
                     64: 
                     65: Most people seem to be using amd64.
                     66: 
                     67: To build zfs, one puts MKZFS=yes in mk.conf.  This is default on amd64
                     68: and aarch64 on netbsd-9.  In current, it is also default on sparc64.
                     69: 
                     70: More or less, zfs can be enabled on an architecture when it is known
                     71: to build and run reliably.  (Of course, users are welcome to build it
                     72: and report.)
                     73: 
                     74: # NetBSD-specific information
                     75: 
                     76: ## rc.conf
                     77: 
                     78: The main configuration is to put zfs=YES in rc.conf, so that the rc.d
                     79: scripts bring up ZFS and mount ZFS filesystems.
                     80: 
                     81: ## mount order
                     82: 
1.3       gdt        83: NetBSD 9 mounts other filesystems and then ZFS filesystems.  This can
                     84: be a problem if /usr/pkgsrc is on ZFS and /usr/pkgsrc/distfiles is on
                     85: NFS.  A workaround is to use noauto and do the mounts in
                     86: /etc/rc.local.
                     87: 
                     88: NetBSD current after 20200301 mounts ZFS first. \todo Explain
                     89: consequences.
1.1       gdt        90: 
                     91: ## TRIM
                     92: 
                     93: There is some notion of TRIM and zfs using it.
                     94: 
                     95: \todo Explain how this relates to NetBSD.
                     96: 
                     97: # Memory usage
                     98: 
                     99: Basically, ZFS uses lots of memory and most people run it on systems
                    100: with large amounts of memory.  NetBSD works well on systems with
                    101: comparatively small amounts of memory.  So a natural question is how
                    102: well ZFS works on one's VAX with 2M of RAM :-)
                    103: 
                    104: More seriously, one might ask if is reasonable to run ZFS on a RPI3
                    105: with 1G of RAM, or even if it is reasonable on a system with 4G.
                    106: 
                    107: \todo Give ballpark level for minimum sane RAM, and the amount which
                    108: is cleanly enough.
                    109: 
1.2       gdt       110: FreeBSD has some documentation about memory use.  There is a notion of
                    111: a minimum of 1G, and using 1G for 1T of storage, and more if
                    112: deduplication is enabled.  FreeBSD considers all i386 systems to be
                    113: low memory; this appears to be a clue.
1.1       gdt       114: 
1.2       gdt       115: \todo Explain if the FreeBSD sysctl list applies, or if not what we
                    116: should do instead.
                    117: 
                    118: [FreeBSD low memory documentation](https://www.freebsd.org/doc/handbook/zfs-advanced.html)
1.1       gdt       119: 
                    120: # Interoperability with other systems
                    121: 
                    122: \todo Explain pool version and feature flags relationship to FreeBSD,
                    123: Linux, OpenIndiana/Illumos/?, and ?
                    124: 
                    125: