Annotation of wikisrc/zfs.mdwn, revision 1.23

1.1       gdt         1: # ZFS on NetBSD
                      2: 
1.11      gdt         3: This page attempts to do two things: provide enough orientation and
1.13      wiz         4: pointers to standard ZFS documentation for NetBSD users who are new to
1.11      gdt         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)
1.14      gdt        18:   - [OpenZFS admin docs index page](https://github.com/openzfs/zfs/wiki/Admin-Documentation)
1.1       gdt        19: 
1.21      gdt        20:   - https://en.wikipedia.org/wiki/ZFS
                     21: 
1.1       gdt        22: # Status of ZFS in NetBSD
                     23: 
1.21      gdt        24: ## Sources of ZFS code
1.12      gdt        25: 
                     26: \todo Verify/fix.
                     27: 
1.21      gdt        28: Currently, there are multiple ZFS projects and codebases:
1.12      gdt        29: 
                     30:   - ZFS as released under the CDDL (common ancestor)
1.21      gdt        31:   - [OpenZFS](http://www.open-zfs.org/wiki/Main_Page) [github wiki](https://github.com/openzfs/zfs/wiki)
1.12      gdt        32:   - [zfsonlinux](https://zfsonlinux.org/)
1.21      gdt        33:   - [OpenZFS on OS X ](https://openzfsonosx.org/) [repo](https://github.com/openzfsonosx)
1.12      gdt        34:   - proprietary ZFS in Solaris (not relevant in open source)
                     35: 
                     36: OpenZFS is a coordinating project to align open ZFS codebases.  There
                     37: is a notion of a shared core codebase and OS-specific adaptation code.
1.23    ! gdt        38: As of early 2020, it appears that there are two co-root repositories:
        !            39: illumos and zfsonlinux, with a notion that fixes and improvements
        !            40: should be cross-shared.  This is different from the situation through
        !            41: late 2019 where sharing was done via a designated sharing repository,
        !            42: and appears to be a new, more efficient, procedure among cooperating
        !            43: people, rather than any kind of fork.
1.12      gdt        44: 
1.23    ! gdt        45:   - [deprecation of OpenZFS repo](https://github.com/openzfs/openzfs/)
1.22      gdt        46:   - [zfsonlinux relationship to OpenZFS](https://github.com/openzfs/zfs/wiki/OpenZFS-Patches)
                     47: 
1.23    ! gdt        48: \todo Explain how FreeBSD code relates to zfsonlinux (imported/merged and fixes pushed upstream?).
        !            49: 
        !            50: \todo Explain how the NetBSD code relates (imported from FreeBSD? intent to continue to track?)
        !            51: 
        !            52: \todo Explain if NetBSD has a plan to join zfsonlinux as a first-class
        !            53: member, vs tracking via FreeBSD.
        !            54: 
        !            55: \todo Explain how OpenZFS on OS X relates (tracks zfsonlinux?).
1.21      gdt        56: 
1.16      gdt        57: See [FreeBSD's history](https://wiki.freebsd.org/ZFSTuningGuide).
1.14      gdt        58: 
1.12      gdt        59: ## NetBSD code history
                     60: 
                     61: \todo This section really needs help.
                     62: 
1.22      gdt        63: Before NetBSD 8, NetBSD imported ZFS code from ?, which was version ?
1.12      gdt        64: 
                     65: Before NetBSD 9, NetBSD imported updated ZFS code from FreeBSD.  That
1.22      gdt        66: FreeBSD code came from ?, which was version ?
1.1       gdt        67: 
                     68: ## NetBSD 8 and earlier
                     69: 
                     70: While there is some ZFS code, it is old, and seems to have significant
                     71: problems.  If one wants to use ZFS, first upgrade to NetBSD 9.  It is
                     72: unlikely that anyone is interested in helping, other than telling you
                     73: to upgrade to 9.
                     74: 
1.13      wiz        75: (Reports of how well NetBSD 8 works are welcome on netbsd-users, if it
1.1       gdt        76: can actually be recommended for use.)
                     77: 
                     78: ## NetBSD 9
                     79: 
                     80: There have been fixes since 9.0 RELEASE.  It is best to upgrade along
1.12      gdt        81: the netbsd-9 branch, but the release should be ok.  Most aspects work solidly.
1.1       gdt        82: 
1.12      gdt        83: \todo Explain this in terms of versions of FreeBSD OpenZFS and/or
                     84: zfsonlinux.
1.1       gdt        85: 
                     86: \todo This supports pool version 28/5000 (really true?).  Of the
                     87: feature flags found in modern OpenZFS, \todo are supported.
                     88: 
1.7       gdt        89: Generally, fixes to ZFS in current will be pulled up to 9, but new
1.5       gdt        90: features typically will not be.
                     91: 
1.1       gdt        92: ## NetBSD current
                     93: 
1.5       gdt        94: The ZFS code in current is very similar to that in 9.
                     95: 
1.9       gdt        96: There is initial support for [[ZFS root|wiki/RootOnZFS]], via booting from
1.5       gdt        97: ffs and pivoting.
1.1       gdt        98: 
1.14      gdt        99: One can make a ccd using a zvol as a component.  See the zvol section below.
1.1       gdt       100: 
1.16      gdt       101: ## Things that aren't supported yet
1.1       gdt       102: 
1.8       gdt       103: \todo hotswap (maybe - not clear exactly what this means)
1.1       gdt       104: 
1.13      wiz       105: \todo direct boot into zfs root (via boot blocks reading zfs)
1.1       gdt       106: 
                    107: ## Architectures
                    108: 
                    109: Most people seem to be using amd64.
                    110: 
                    111: To build zfs, one puts MKZFS=yes in mk.conf.  This is default on amd64
                    112: and aarch64 on netbsd-9.  In current, it is also default on sparc64.
                    113: 
                    114: More or less, zfs can be enabled on an architecture when it is known
                    115: to build and run reliably.  (Of course, users are welcome to build it
                    116: and report.)
                    117: 
                    118: # NetBSD-specific information
                    119: 
                    120: ## rc.conf
                    121: 
                    122: The main configuration is to put zfs=YES in rc.conf, so that the rc.d
1.13      wiz       123: scripts bring up ZFS and mount ZFS file systems.
1.1       gdt       124: 
1.14      gdt       125: ## pool locations
                    126: 
                    127: One can add disks or parts of disks into pools.  Methods of specifying
                    128: areas to be included include:
                    129: 
                    130:   - entire disks (e.g., /dev/rwd0d on amd64)
                    131:   - disklabel partitions (e.g., /dev/sd0e)
                    132:   - wedges (e.g., /dev/dk0)
                    133: 
1.6       gdt       134: ## legacy vs ? mount points
                    135: 
                    136: \todo Explain, if this is NetBSD specific.  Explain consequences, as
                    137: this seems to have something to do with mount ordering.
                    138: 
1.1       gdt       139: ## mount order
                    140: 
1.13      wiz       141: NetBSD 9 mounts other file systems and then ZFS file systems.  This can
1.3       gdt       142: be a problem if /usr/pkgsrc is on ZFS and /usr/pkgsrc/distfiles is on
                    143: NFS.  A workaround is to use noauto and do the mounts in
                    144: /etc/rc.local.
                    145: 
                    146: NetBSD current after 20200301 mounts ZFS first. \todo Explain
                    147: consequences.
1.1       gdt       148: 
1.19      gdt       149: ## NFS
                    150: 
                    151: \todo Verify if this is accurate.
                    152: 
                    153: zfs filesystems can be exported over NFS.  While there are zfs
                    154: commands that appear to be about controlling exports, they simply
                    155: print information that can be added to exports(5).
                    156: 
1.20      gdt       157: This is reported to work on 9.0 STABLE, but to cause a panic on
                    158: current (20200302).
                    159: 
1.14      gdt       160: ## zvol
                    161: 
                    162: Within a ZFS pool, the standard approach is to have file systems, but
                    163: one can also create a zvol, which is a block device of a certain size.
                    164: 
                    165: \todo The zvol will appear as /dev/???? and can be used in many
                    166: respects like a slice.  However, the system will not read disklabels
                    167: and gpt labels from a zvol; in this respect it is more like a disklabel
                    168: partition or wedge than a disk drive.
                    169: 
                    170: \todo Explain that one can export a zvol via iscsi.
                    171: 
                    172: \todo Explain if one can swap on a zvol.
                    173: 
                    174: \todo Explain that one can use ccd to create a normal-looking disk
                    175: from a zvol.  This allows reading a GPT label from the zvol, which is
                    176: useful in case the zvol had been exported via iscsi and some other
                    177: system created a label.
                    178: 
1.1       gdt       179: ## TRIM
                    180: 
                    181: There is some notion of TRIM and zfs using it.
                    182: 
                    183: \todo Explain how this relates to NetBSD.
                    184: 
                    185: # Memory usage
                    186: 
                    187: Basically, ZFS uses lots of memory and most people run it on systems
                    188: with large amounts of memory.  NetBSD works well on systems with
                    189: comparatively small amounts of memory.  So a natural question is how
                    190: well ZFS works on one's VAX with 2M of RAM :-)
                    191: 
1.11      gdt       192: More seriously, one might ask if it is reasonable to run ZFS on a RPI3
1.1       gdt       193: with 1G of RAM, or even if it is reasonable on a system with 4G.
                    194: 
                    195: \todo Give ballpark level for minimum sane RAM, and the amount which
                    196: is cleanly enough.
                    197: 
1.10      gdt       198: For now, a good guess is that a 4G system with only 1T of disk is
1.18      gdt       199: probably ok, and that 1G is very likely not ok.
1.10      gdt       200: 
1.2       gdt       201: FreeBSD has some documentation about memory use.  There is a notion of
1.18      gdt       202: a minimum of 1G (used for ZFS), and using 1G for 1T of storage, and
                    203: more if deduplication is enabled.  FreeBSD considers all i386 systems
                    204: to be low memory; this appears to be a clue.
1.1       gdt       205: 
1.2       gdt       206: \todo Explain if the FreeBSD sysctl list applies, or if not what we
                    207: should do instead.
                    208: 
1.7       gdt       209:   - [FreeBSD low memory documentation](https://www.freebsd.org/doc/handbook/zfs-advanced.html)
1.1       gdt       210: 
                    211: # Interoperability with other systems
                    212: 
                    213: \todo Explain pool version and feature flags relationship to FreeBSD,
                    214: Linux, OpenIndiana/Illumos/?, and ?
                    215: 
1.18      gdt       216: \todo Explain how to configure a pool in terms of version/features for
                    217: use with particula other systems.
                    218: 
1.14      gdt       219: # Quick Start
                    220: 
                    221: See the [FreeBSD Quickstart
                    222: Guide](https://www.freebsd.org/doc/handbook/zfs-quickstart.html); only
                    223: the first item is NetBSD specific.
                    224: 
                    225:   - Put zfs=YES in rc.conf.
                    226: 
                    227:   - Create a pool as "zpool create pool1 /dev/dk0".
                    228: 
                    229:   - df and see /pool1
                    230: 
1.17      gdt       231:   - Really, read the FreeBSD docs and the other linked documentation above.

CVSweb for NetBSD wikisrc <wikimaster@NetBSD.org> software: FreeBSD-CVSweb