Understood. Another question. If the vm treat the vol-0 as a normal block device, is it necessary to partition? If not, the fdisk will show Disk /dev/vdb doesn't contain a valid partition table. If yes, how can I extend the volume on the vm? It seems that treat the volume as a normal block device is not a good idea.
On Tue, Nov 27, 2012 at 4:52 AM, Dean Troyer <[email protected]> wrote: > On Mon, Nov 26, 2012 at 6:51 AM, Lei Zhang <[email protected]> > wrote: > > I creat a lvm named vol-0 and attach it to the machine com-0. After a > period > > of time, the vol-0 is full and I want to extend it. At now, I have two > > solutions. > > Nested LVM gets tricky so I want to be sure I am clear on your setup: > > * Your host has a logical volume (LV) 'vol-0' that is attached to a VM > named 'com-0'. > * com-0 uses the attached logical volume (vol-0 on the host) as a > physical volume (PV) for its own LVM configuration. > > > Because the vol-0 is manage by the LVM on the hoster. So I can extend the > > size of it by using lvextend. But I meet that the vm(com-0) can not be > aware > > this. Should I make some extrac operations like reseize2fs? I have no > ideas. > > If vol-0 is used directly as a block device with a filesystem on it > (older Xen installs often did this) then a resize2fs is sufficient to > recognize the additional space. It appears this is _not_ your > configuration, correct? > > If vol-0 is used as a PV in com-0 then you can run pvresize inside > com-0 and have com-0's LVM recognize the additional space. > > > In the vm (com-0), I can treat the vol-0 as a normal block device and > create > > lvm on it. When need more space, the hoster can "plug" a new lvm > > device(vol-1) on it. In the vm, I can add it to the lvm. But I found > another > > Correct, this is another way to increase the space available to > cpm-0's volume groups. > > > problem. Because the vol-* is not real block device, when I create lvm on > > it, the hoster is aware of it. The result is that on the hoster, another > PV > > is created base on a lvm partition like bellow. I want to know, it is > > acceptable? > > To fix this you need to adjust the filter on your host's > /etc/lvm/lvm.conf. You can either reject any physical volumes found > for VMs: > > filter = ["r|/dev/cinder-volumes/.*", "a/.*/"] # reject cinder > devices, alow everything else > > or you can only look at particular divice files for physical devices: > > filter = ["a/dev/sd.*"] # look only at SCSI disks for physical > devices > > That last one will likely need adjusting for your local block device names. > > dt > > -- > > Dean Troyer > [email protected] > -- Lei Zhang Blog: http://jeffrey4l.github.com twitter/weibo: @jeffrey4l
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