1: # ZFS on NetBSD
3: This page attempts to do two things: provide enough orientation and
4: pointers to standard ZFS documentation for NetBSD users who are new to
5: ZFS, and to describe NetBSD-specific ZFS information. It is
6: emphatically not a tutorial or an introduction to ZFS.
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.
12: # Documentation Pointers
14: See the man pages for zfs(8) and zpool(8).
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)
18: - [OpenZFS admin docs index page](https://github.com/openzfs/zfs/wiki/Admin-Documentation)
20: # Status of ZFS in NetBSD
22: ## Sources
24: \todo Verify/fix.
26: Currently, there are multiple ZFS projects/codebases:
28: - ZFS as released under the CDDL (common ancestor)
29: - [OpenZFS](http://www.open-zfs.org/wiki/Main_Page)
30: - [zfsonlinux](https://zfsonlinux.org/)
31: - proprietary ZFS in Solaris (not relevant in open source)
33: OpenZFS is a coordinating project to align open ZFS codebases. There
34: is a notion of a shared core codebase and OS-specific adaptation code.
36: See [FreeBSD's history](https://wiki.freebsd.org/ZFSTuningGuide).
38: \todo Explain the relationship between OpenZFS and zfsonlinux.
40: ## NetBSD code history
42: \todo This section really needs help.
44: Before NetBSD 8, NetBSD imported ZFS code from ?
46: Before NetBSD 9, NetBSD imported updated ZFS code from FreeBSD. That
47: FreeBSD code came from ?
49: ## NetBSD 8 and earlier
51: While there is some ZFS code, it is old, and seems to have significant
52: problems. If one wants to use ZFS, first upgrade to NetBSD 9. It is
53: unlikely that anyone is interested in helping, other than telling you
54: to upgrade to 9.
56: (Reports of how well NetBSD 8 works are welcome on netbsd-users, if it
57: can actually be recommended for use.)
59: ## NetBSD 9
61: There have been fixes since 9.0 RELEASE. It is best to upgrade along
62: the netbsd-9 branch, but the release should be ok. Most aspects work solidly.
64: \todo Explain this in terms of versions of FreeBSD OpenZFS and/or
67: \todo This supports pool version 28/5000 (really true?). Of the
68: feature flags found in modern OpenZFS, \todo are supported.
70: Generally, fixes to ZFS in current will be pulled up to 9, but new
71: features typically will not be.
73: ## NetBSD current
75: The ZFS code in current is very similar to that in 9.
77: There is initial support for [[ZFS root|wiki/RootOnZFS]], via booting from
78: ffs and pivoting.
80: One can make a ccd using a zvol as a component. See the zvol section below.
82: ## Things that aren't supported yet
84: \todo hotswap (maybe - not clear exactly what this means)
86: \todo direct boot into zfs root (via boot blocks reading zfs)
88: ## Architectures
90: Most people seem to be using amd64.
92: To build zfs, one puts MKZFS=yes in mk.conf. This is default on amd64
93: and aarch64 on netbsd-9. In current, it is also default on sparc64.
95: More or less, zfs can be enabled on an architecture when it is known
96: to build and run reliably. (Of course, users are welcome to build it
97: and report.)
99: # NetBSD-specific information
101: ## rc.conf
103: The main configuration is to put zfs=YES in rc.conf, so that the rc.d
104: scripts bring up ZFS and mount ZFS file systems.
106: ## pool locations
108: One can add disks or parts of disks into pools. Methods of specifying
109: areas to be included include:
111: - entire disks (e.g., /dev/rwd0d on amd64)
112: - disklabel partitions (e.g., /dev/sd0e)
113: - wedges (e.g., /dev/dk0)
115: ## legacy vs ? mount points
117: \todo Explain, if this is NetBSD specific. Explain consequences, as
118: this seems to have something to do with mount ordering.
120: ## mount order
122: NetBSD 9 mounts other file systems and then ZFS file systems. This can
123: be a problem if /usr/pkgsrc is on ZFS and /usr/pkgsrc/distfiles is on
124: NFS. A workaround is to use noauto and do the mounts in
127: NetBSD current after 20200301 mounts ZFS first. \todo Explain
130: ## NFS
132: \todo Verify if this is accurate.
134: zfs filesystems can be exported over NFS. While there are zfs
135: commands that appear to be about controlling exports, they simply
136: print information that can be added to exports(5).
138: This is reported to work on 9.0 STABLE, but to cause a panic on
139: current (20200302).
141: ## zvol
143: Within a ZFS pool, the standard approach is to have file systems, but
144: one can also create a zvol, which is a block device of a certain size.
146: \todo The zvol will appear as /dev/???? and can be used in many
147: respects like a slice. However, the system will not read disklabels
148: and gpt labels from a zvol; in this respect it is more like a disklabel
149: partition or wedge than a disk drive.
151: \todo Explain that one can export a zvol via iscsi.
153: \todo Explain if one can swap on a zvol.
155: \todo Explain that one can use ccd to create a normal-looking disk
156: from a zvol. This allows reading a GPT label from the zvol, which is
157: useful in case the zvol had been exported via iscsi and some other
158: system created a label.
160: ## TRIM
162: There is some notion of TRIM and zfs using it.
164: \todo Explain how this relates to NetBSD.
166: # Memory usage
168: Basically, ZFS uses lots of memory and most people run it on systems
169: with large amounts of memory. NetBSD works well on systems with
170: comparatively small amounts of memory. So a natural question is how
171: well ZFS works on one's VAX with 2M of RAM :-)
173: More seriously, one might ask if it is reasonable to run ZFS on a RPI3
174: with 1G of RAM, or even if it is reasonable on a system with 4G.
176: \todo Give ballpark level for minimum sane RAM, and the amount which
177: is cleanly enough.
179: For now, a good guess is that a 4G system with only 1T of disk is
180: probably ok, and that 1G is very likely not ok.
182: FreeBSD has some documentation about memory use. There is a notion of
183: a minimum of 1G (used for ZFS), and using 1G for 1T of storage, and
184: more if deduplication is enabled. FreeBSD considers all i386 systems
185: to be low memory; this appears to be a clue.
187: \todo Explain if the FreeBSD sysctl list applies, or if not what we
188: should do instead.
190: - [FreeBSD low memory documentation](https://www.freebsd.org/doc/handbook/zfs-advanced.html)
192: # Interoperability with other systems
194: \todo Explain pool version and feature flags relationship to FreeBSD,
195: Linux, OpenIndiana/Illumos/?, and ?
197: \todo Explain how to configure a pool in terms of version/features for
198: use with particula other systems.
200: # Quick Start
202: See the [FreeBSD Quickstart
203: Guide](https://www.freebsd.org/doc/handbook/zfs-quickstart.html); only
204: the first item is NetBSD specific.
206: - Put zfs=YES in rc.conf.
208: - Create a pool as "zpool create pool1 /dev/dk0".
210: - df and see /pool1
212: - Really, read the FreeBSD docs and the other linked documentation above.
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