Annotation of wikisrc/zfs.mdwn, revision 1.11

1.1       gdt         1: # ZFS on NetBSD
                      2: 
1.11    ! gdt         3: This page attempts to do two things: provide enough orientation and
        !             4: pointers to dstandard ZFS documentation for NetBSD users who are new to
        !             5: ZFS, and to describe NetBSD-specific ZFS information.  It is
1.1       gdt         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: 
1.7       gdt        43: Generally, fixes to ZFS in current will be pulled up to 9, but new
1.5       gdt        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: 
1.9       gdt        50: There is initial support for [[ZFS root|wiki/RootOnZFS]], via booting from
1.5       gdt        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: 
1.8       gdt        59: \todo hotswap (maybe - not clear exactly what this means)
1.1       gdt        60: 
1.8       gdt        61: \todo direct boot into zfs root (via bootblocks reading zfs)
1.1       gdt        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: 
1.6       gdt        81: ## legacy vs ? mount points
                     82: 
                     83: \todo Explain, if this is NetBSD specific.  Explain consequences, as
                     84: this seems to have something to do with mount ordering.
                     85: 
1.1       gdt        86: ## mount order
                     87: 
1.3       gdt        88: NetBSD 9 mounts other filesystems and then ZFS filesystems.  This can
                     89: be a problem if /usr/pkgsrc is on ZFS and /usr/pkgsrc/distfiles is on
                     90: NFS.  A workaround is to use noauto and do the mounts in
                     91: /etc/rc.local.
                     92: 
                     93: NetBSD current after 20200301 mounts ZFS first. \todo Explain
                     94: consequences.
1.1       gdt        95: 
                     96: ## TRIM
                     97: 
                     98: There is some notion of TRIM and zfs using it.
                     99: 
                    100: \todo Explain how this relates to NetBSD.
                    101: 
                    102: # Memory usage
                    103: 
                    104: Basically, ZFS uses lots of memory and most people run it on systems
                    105: with large amounts of memory.  NetBSD works well on systems with
                    106: comparatively small amounts of memory.  So a natural question is how
                    107: well ZFS works on one's VAX with 2M of RAM :-)
                    108: 
1.11    ! gdt       109: More seriously, one might ask if it is reasonable to run ZFS on a RPI3
1.1       gdt       110: with 1G of RAM, or even if it is reasonable on a system with 4G.
                    111: 
                    112: \todo Give ballpark level for minimum sane RAM, and the amount which
                    113: is cleanly enough.
                    114: 
1.10      gdt       115: For now, a good guess is that a 4G system with only 1T of disk is
                    116: probably ok, 1G is very likely not ok.
                    117: 
1.2       gdt       118: FreeBSD has some documentation about memory use.  There is a notion of
                    119: a minimum of 1G, and using 1G for 1T of storage, and more if
                    120: deduplication is enabled.  FreeBSD considers all i386 systems to be
                    121: low memory; this appears to be a clue.
1.1       gdt       122: 
1.2       gdt       123: \todo Explain if the FreeBSD sysctl list applies, or if not what we
                    124: should do instead.
                    125: 
1.7       gdt       126:   - [FreeBSD low memory documentation](https://www.freebsd.org/doc/handbook/zfs-advanced.html)
1.1       gdt       127: 
                    128: # Interoperability with other systems
                    129: 
                    130: \todo Explain pool version and feature flags relationship to FreeBSD,
                    131: Linux, OpenIndiana/Illumos/?, and ?
                    132: 
                    133: 

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