Annotation of wikisrc/zfs.mdwn, revision 1.12

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: 
1.12    ! gdt        21: ## Sources
        !            22: 
        !            23: \todo Verify/fix.
        !            24: 
        !            25: Currently, there are multiple ZFS projects/codebases:
        !            26: 
        !            27:   - ZFS as released under the CDDL (common ancestor)
        !            28:   - [OpenZFS](http://www.open-zfs.org/wiki/Main_Page)
        !            29:   - [zfsonlinux](https://zfsonlinux.org/)
        !            30:   - proprietary ZFS in Solaris (not relevant in open source)
        !            31: 
        !            32: OpenZFS is a coordinating project to align open ZFS codebases.  There
        !            33: is a notion of a shared core codebase and OS-specific adaptation code.
        !            34: 
        !            35: ## NetBSD code history
        !            36: 
        !            37: \todo This section really needs help.
        !            38: 
        !            39: Before NetBSD 8, NetBSD imported ZFS code from ?
        !            40: 
        !            41: Before NetBSD 9, NetBSD imported updated ZFS code from FreeBSD.  That
        !            42: FreeBSD code came from ?
1.1       gdt        43: 
                     44: ## NetBSD 8 and earlier
                     45: 
                     46: While there is some ZFS code, it is old, and seems to have significant
                     47: problems.  If one wants to use ZFS, first upgrade to NetBSD 9.  It is
                     48: unlikely that anyone is interested in helping, other than telling you
                     49: to upgrade to 9.
                     50: 
                     51: (Reports of how well NetBDS 8 works are welcome on netbsd-users, if it
                     52: can actually be recommended for use.)
                     53: 
                     54: ## NetBSD 9
                     55: 
                     56: There have been fixes since 9.0 RELEASE.  It is best to upgrade along
1.12    ! gdt        57: the netbsd-9 branch, but the release should be ok.  Most aspects work solidly.
1.1       gdt        58: 
1.12    ! gdt        59: \todo Explain this in terms of versions of FreeBSD OpenZFS and/or
        !            60: zfsonlinux.
1.1       gdt        61: 
                     62: \todo This supports pool version 28/5000 (really true?).  Of the
                     63: feature flags found in modern OpenZFS, \todo are supported.
                     64: 
1.7       gdt        65: Generally, fixes to ZFS in current will be pulled up to 9, but new
1.5       gdt        66: features typically will not be.
                     67: 
1.1       gdt        68: ## NetBSD current
                     69: 
1.5       gdt        70: The ZFS code in current is very similar to that in 9.
                     71: 
1.9       gdt        72: There is initial support for [[ZFS root|wiki/RootOnZFS]], via booting from
1.5       gdt        73: ffs and pivoting.
1.1       gdt        74: 
                     75: One can make a ccd using a zvol as a component.  This allows reading a
                     76: GPT label from the zvol, which is useful in case the zvol had been
                     77: exported via iscsi and some other system created a label.
                     78: 
                     79: ## things that aren't suported yet
                     80: 
1.8       gdt        81: \todo hotswap (maybe - not clear exactly what this means)
1.1       gdt        82: 
1.8       gdt        83: \todo direct boot into zfs root (via bootblocks reading zfs)
1.1       gdt        84: 
                     85: ## Architectures
                     86: 
                     87: Most people seem to be using amd64.
                     88: 
                     89: To build zfs, one puts MKZFS=yes in mk.conf.  This is default on amd64
                     90: and aarch64 on netbsd-9.  In current, it is also default on sparc64.
                     91: 
                     92: More or less, zfs can be enabled on an architecture when it is known
                     93: to build and run reliably.  (Of course, users are welcome to build it
                     94: and report.)
                     95: 
                     96: # NetBSD-specific information
                     97: 
                     98: ## rc.conf
                     99: 
                    100: The main configuration is to put zfs=YES in rc.conf, so that the rc.d
                    101: scripts bring up ZFS and mount ZFS filesystems.
                    102: 
1.6       gdt       103: ## legacy vs ? mount points
                    104: 
                    105: \todo Explain, if this is NetBSD specific.  Explain consequences, as
                    106: this seems to have something to do with mount ordering.
                    107: 
1.1       gdt       108: ## mount order
                    109: 
1.3       gdt       110: NetBSD 9 mounts other filesystems and then ZFS filesystems.  This can
                    111: be a problem if /usr/pkgsrc is on ZFS and /usr/pkgsrc/distfiles is on
                    112: NFS.  A workaround is to use noauto and do the mounts in
                    113: /etc/rc.local.
                    114: 
                    115: NetBSD current after 20200301 mounts ZFS first. \todo Explain
                    116: consequences.
1.1       gdt       117: 
                    118: ## TRIM
                    119: 
                    120: There is some notion of TRIM and zfs using it.
                    121: 
                    122: \todo Explain how this relates to NetBSD.
                    123: 
                    124: # Memory usage
                    125: 
                    126: Basically, ZFS uses lots of memory and most people run it on systems
                    127: with large amounts of memory.  NetBSD works well on systems with
                    128: comparatively small amounts of memory.  So a natural question is how
                    129: well ZFS works on one's VAX with 2M of RAM :-)
                    130: 
1.11      gdt       131: More seriously, one might ask if it is reasonable to run ZFS on a RPI3
1.1       gdt       132: with 1G of RAM, or even if it is reasonable on a system with 4G.
                    133: 
                    134: \todo Give ballpark level for minimum sane RAM, and the amount which
                    135: is cleanly enough.
                    136: 
1.10      gdt       137: For now, a good guess is that a 4G system with only 1T of disk is
                    138: probably ok, 1G is very likely not ok.
                    139: 
1.2       gdt       140: FreeBSD has some documentation about memory use.  There is a notion of
                    141: a minimum of 1G, and using 1G for 1T of storage, and more if
                    142: deduplication is enabled.  FreeBSD considers all i386 systems to be
                    143: low memory; this appears to be a clue.
1.1       gdt       144: 
1.2       gdt       145: \todo Explain if the FreeBSD sysctl list applies, or if not what we
                    146: should do instead.
                    147: 
1.7       gdt       148:   - [FreeBSD low memory documentation](https://www.freebsd.org/doc/handbook/zfs-advanced.html)
1.1       gdt       149: 
                    150: # Interoperability with other systems
                    151: 
                    152: \todo Explain pool version and feature flags relationship to FreeBSD,
                    153: Linux, OpenIndiana/Illumos/?, and ?
                    154: 
                    155: 

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