Date: Mon, 11 Feb 2019 23:03:41 +0000 From: Frank Leonhardt <freebsd-doc@fjl.co.uk> To: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: mounting/exporting/importing a zfs volume Message-ID: <4465134c-ae48-d39b-dd87-9514da577cc2@fjl.co.uk> In-Reply-To: <20190211170312.GA76683@admin.sibptus.ru> References: <20190211170312.GA76683@admin.sibptus.ru>
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On 11/02/2019 17:03, Victor Sudakov wrote: > Dear Colleagues, > > vm-bhyve keeps virtual machines on zfs volumes with volmode=dev. How can > I access/mount the filesystems within the volume when the virtual host > is offline? > > If I kept virtual disks in raw files, I could access them as devices > with mdconfig. But: > > root@newserv:~ # mdconfig -a -f /dev/zvol/zroot/vm/mail/disk0 > mdconfig: /dev/zvol/zroot/vm/mail/disk0 is not a regular file > root@newserv:~ # > > Also, how can I exchange those zfs volumes for use with other > hypervisors? They are not real raw disk files so I cannot use > sysutils/vmdktool etc. > I don't know this, but I'll guess(!) If you've set volmode to dev then you get a cdev device in devfs, and you'll never get it to mount. Try using geom instead (which IIRC is the default). HOWEVER, I suspect you're doing this because you're hoping that a ZFS volume is faster than a file. I went through this, in the hope it wouldn't do CoW and would therefore be a lot better for databases. I was disappointed! Bascially, it's no better than a ZFS file. If that was your plan, use a UFS partition. I don't use ZFS volumes any more; I think they're more useful on Solaris. A md mapped on to a ZFS file seems to be the BSD way, and for VMs just use a file in its own dataset. You can then clone the dataset. Just what you need for nearly identical VMs. Regards, Frank.help
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