Yesterday we hung up a magnet board (of a German discounter) on a wall. This simple task led to the following learning experience:
Hanging something on a wall (which includes drilling a hole) should not be done the agile way but rather by the waterfall model.
As validation and QA happened after the first iteration we now will return the magnet board, but therefore we have two screws at a prominent place in the wall.
This use case just reappeared the third time and I had to lookup the commands again. So I am documenting them here, to easier find them the next time.
Assume the follwoing:
- we have a guest VM running in libvirtd called guest01
- besides its root device it has a data partition backed in an LVM
- the volume group is called vg01 and the logical volume data01
- we want to grow the data partition to 100G
- the resizing should be done online, so without a downtime of the VM
First we need to resize the logical volume:
lvresize -L 100G /dev/vg01/data01
Next we need to find out the path name of this device in the libvirt VM. The list of all devices can be printed with:
virsh domblklist guest01
Take the path value and use it in the next command (I will use vdX here). The blockresize command will inform libvirtd about the new size of the LVM volume.
virsh blockrezise guest01 --path vdX --size 100
Now the logical volume is bigger and libvirtd propagated the change into the VM. So you can see the new partition size inside the VM. But the file system was not changed yet.
The last step, resizing the file system, has to be done inside the VM:
resize2fs /dev/vdX # for ext[2,3,4]
xfs_growfs /dev/vdX # for xfs
It took me a long evening to figure it out how to do it, but it is possible to install an openSUSE 12.2 with GRUB2 on a disk with GTP partition table and have the entire root partition within LVM (and in my case even have the LVM in a MD RAID). The current openSUSE installer (partitioning and bootloader) does not fully support this use case, but they will however install it correctly even though the warning messages shown might be misleading.
These are my partitions (adapt them to your use case):
- sda (GPT partition table: gpt_sync_mbr)
- 7.84 MB primary, flags: bios_grub (do not format or mount)
- 8 GB primary, flags: raid (raid1, md0), swap
- ? GB primary, flags: raid (raid1, md1), LVM
- sdb (same as sda)
- Note: the first partition of both disks is not part of any raid. The sda1 partition has to be synced manually once after installation to its pendant on sdb.
The first partition has to be unformatted and unmounted and have the flag bios_grub set. This can be done with parted by running (for both disks):
(parted) toggle 1 bios_grub on
(parted) select /dev/sdb
(parted) toggle 1 bios_grub on
This will allow GRUB2 to find space to install its core.img to.
There is more than one way to do this kind of installation. But with YaST you can not (yet) create set the bios_grub flag during installation. Here are two ways which should work pretty nicely (I took the latter):
- Prepare the partition setup before booting the installation media. Make sure to have all partitions setup correctly (including the flags you need). There is no need to create the RAID and LVM beforehand – of course you could, but this is something where YaST has a pretty nice and intuitive graphical UI for. During the installation also make sure that YaST uses the existing partition setup. The default is to propose an own partition setup.
- Start the installation with the plain and empty disks. Do the partitioning via YaST (make sure to use a GTP partition table; see the export button within the YaST partitioner). Let the system do the installation and ignore the warnings that are shown. While the installation process is installing the packages do this:
- Press Ctrl+Alt+Shift+X to open an xterm
- In the xterm run parted and set the flags for the first partitions of each disk
- If you finish this before YaST installs the bootloader everything work smoothly
If you do not manage to do this before the YaST installs the bootloader it will popup an error message with warnings that your setup is totally unsupported and will not be able to boot. Just ignore the warning, but to not yet press the OK button. Continue to toggle the flags in the xterm and close parted. When done, press the OK button of the warning message and YaST will try again to install the bootloader and now will succeed without any error message.
The bootloader will only be installed on /dev/sda by default. So after the first boot sync the content of the first partition of sda to the first one on sdb (e.g. using dd).
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2011 is about to become an interesting year for us.