On Wed, Oct 17, 2012 at 01:51:35PM +1100, Peter Ross wrote:
> Hi Russell,
>
> http://en.wikipedia.org/wiki/ZFS#Storage_pools.";
>
> "ZFS filesystems are built on top of virtual storage pools called zpools."
>
> The management commands are zfs and zpool. The man pages don't have any
> "zvols" in it but Wikipedia's article has.
zfs(8) on my linux system mentions mostly "volumes" but also "zvols" aka
"zfs volumes". almost all commands look like
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
zfs destroy [-fnpRrv] filesystem|volume
zfs clone [-p] [-o property=value] ... snapshot filesystem|volume
zfs rename filesystem|volume|snapshot
zfs set property=value filesystem|volume|snapshot ...
zfs inherit [-r] property filesystem|volume|snapshot ...
zfs receive | recv [-vnFu] filesystem|volume|snapshot
# zfs create -V 2g pool/volumes/vol1
# zfs set shareiscsi=on pool/volumes/vol1
the page has zfsonlinux specific info (like device nodes under
/dev/zvol) but the generic "volumes" info should be relevant to all
current ports of zfs.
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
Creates a volume of the given size. The volume is exported
as a block device in /dev/zvol/path, where path is the name
of the vol ume in the ZFS namespace. The size represents
the logical size as exported by the device. By default, a
reservation of equal size is created.
The FreeBSD man page at the following URL mentions volumes, same as
the zfsonlinux man page.
http://www.freebsd.org/cgi/man.cgi?query=zfs&manpath=FreeBSD+9.0-RELEASE
the text for 'zfs create' is almost identical to the linux version.
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
Creates a volume of the given size. The volume is exported
as a block device in /dev/zvol/{dsk,rdsk}/path, where path
is the name of the volume in the ZFS namespace. The size
represents the logical size as exported by the device. By
default, a reservation of equal size is created.
> Reading http://zfsonlinux.org/example-zvol.html
>
> Never tried (or even thought of trying) to partition "something" created
> with "zfs create" under FreeBSD.. Don't think I can do that - I don't have
> block devices..
A VM given a zvol can partition it just like any other disk.
dunno about freebsd, but on linux i can also access the partitions from the ZFS
server (although i wouldn't want to mount one RW while the VM was running).
# ls -l /dev/zvol/export/{sid,sid-*}
brw-rw---T 1 libvirt-qemu kvm 230, 144 Oct 17 15:46 /dev/zvol/export/sid
brw-rw---T 1 root disk 230, 145 Sep 8 17:10 /dev/zvol/export/sid-part1
brw-rw---T 1 root disk 230, 146 Sep 8 17:10 /dev/zvol/export/sid-part2
> Anyway, would a zvol be significantly better than a file in the zfs as I
> do now?
performance wise? yes, definitely
management convenience? almost certainly. e.g. zfs snapshot instead of
qemu-img snapshot.
craig
--
craig sanders <[email protected]>
BOFH excuse #372:
Forced to support NT servers; sysadmins quit.
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