Migrating VMware Workstation Guests to KVM/qemu

I recently had the need to get one of my VMware Workstation guests (running CentOS 6.4) migrated to a KVM/qemu hypervisor environment. The VM was in the typical multiple file vmdk configuration that VMware Workstation uses.

Note: I've read that if you're migrating a Windows guest or a SCSI-originated guest (or something to that extent), you may get a BSOD or some other boot error. So this may not work for every case.

In summary, the process basically involves converting that multiple file setup into a single file, and then moving that single file into your storage pool for your KVM setup, from which you then import it. Of course, the devil is in the details, so...

Step 1 - Convert VMware multiple file VM into a single file
(note: if you have snapshots, it's best to delete those to ensure you're getting the latest image)
(note: your paths will vary)
# vmware-vdiskmanager -r /home/vm/vmware/c64/c64_disk.vmdk" -t 0 /home/c64.vmdk

During this, I got an error ("VixDiskLib: Invalid configuration file parameter.  Failed to read configuration file.") but I was able to continue on just fine. I assume this is about the VM's configuration, but since I was changing RAM amount and network stuff anyway, I didn't care.

Step 2 - Copy that single file to your storage pool / import location
(note: I'm doing it this way, as the next step is resource-intensive and my destination machine is faster - also, your paths will vary - also, I've setup my storage pool to not be the standard /var/lib/libvirt!)
# rsync -av /home/c64.vmdk [dest-machine]:/home/vm/c64/

Step 3 - Login to destination machine and convert the vmdk into a qemu-compatible format
(note: this will become your VM's main disk image file, so just put it in your pool where you plan on leaving it for the machine)
# qemu-img convert /home/vm/c64/c64.vmdk -O qcow2 /home/vm/c64/c64.img

Step 4 - Start virt-manager and import the VM
# virt-manager
- Create a new machine.
- Choose "Import existing disk image" option.
- Continue configuring it as necessary, and then boot it.

After all is said and done, you will need to tweak a few things (e.g. NIC/MAC, persistent net rules file, etc.), but you should basically be up and running.

Headless CentOS 7 Virtualization Host: Part 1 - Host Installation & Setup

Here is how I setup a headless (no monitor) VM host on CentOS 7.2

Ensure your host's CPU can support virtualization (the result should be > 0):

# egrep -c '(vmx|svm)' /proc/cpuinfo

Install the KVM hypervisor and its necessary packages (this is competitive with vmware):

# yum install kvm libvirt virt-install qemu-kvm

Make sure the host's kernel is ready to perform NAT with the hypervisor for the VM guests. First we'll enable IP forwarding on the host:

# echo "net.ipv4.ip_forward = 1" | sudo tee /etc/sysctl.d/99-ipforward.conf
# sysctl -p /etc/sysctl.d/99-ipforward.conf

Then, we'll modify the network adapter's configuration to use a bridge adapter (in my case, I'm using eth1). Open the config file for editing, comment out everything IP-related (IP, gateway, DNS, etc.), and add a link to the bridge configuration file that we'll add next:

# vim /etc/sysconfig/network-scripts/ifcfg-eth1

BRIDGE=virbr0

Next, we need to create a bridge adapter configuration file and add the following lines (your info will probably be same as what you commented out above):

# vim /etc/sysconfig/network-scripts/ifcfg-virbr0 

DEVICE="virbr0"
TYPE=BRIDGE
ONBOOT=yes
BOOTPROTO=static
IPADDR="[YOURS]"
NETMASK="[YOURS]"
GATEWAY="[YOURS]"
DNS1="[YOURS]"

If possible, reboot the machine to ensure kernel modules and network settings load and initialize.

Finally, just verify your installation and configuration:

# lsmod | grep kvm
# ip a show virbr0
# virsh -c qemu:///system list

Linux Partitions >2TB

For Linux hard drive partitions larger than 2TB, fdisk just doesn't cut it. You'll have to use parted, instead. But keep in mind that since this parted method uses GPT (part of EFI) instead of the old MBR type supported by most/all BIOS, you'll need to make sure your BIOS supports it (most newer ones should).

The example I'm using in my case was for a brand-new 3TB secondary storage device (no existing partitions), with the primary drive being for boot and of the MBR type on a smaller dedicated hard drive... hence "sdb" in the example below, instead of "sda."

First, verify the size of your drive:

# fdisk -l /dev/sdb

Then, get into the GNU parted shell:

# parted /dev/sdb

Once in the parted shell, issue the following commands...
First, create a GPT partition table:

(parted) mklabel gpt

Second, tell parted you'd like to use TB as the unit:

(parted) unit TB

Then, tell parted to create the 3TB partition:

(parted) mkpart primary 0.00TB 3.00TB

You may verify the partition table and quit:

(parted) print

(parted) quit

After that, all you have to do is create your file system and mount the drive.

 

 

Safely Enlarging a Linux /home Partition

I recently cloned a 1TB server hard drive onto a 1.2TB disk, using Clonezilla. This resulted in 0.2TB being unutilized, so I had to enlarge it. But how to do so without losing your data? Something like this (in my case, I needed to enlarge /dev/sda3, a primary partition):

# fdisk /dev/sda

Print the current partition table (so you can note the starting cylinder of the partition you're going to enlarge).

After noting the starting cylinder, delete the third partition.

Re-create the third partition. You MUST make sure it starts with the cylinder noted above! In my case, this was all just defaults. When done, just write the table to disk and reboot.

Next, you'll use the resize command in Linux to expand the file system to match the partition it's on.

# resize2fs /dev/sda3

Here is what I was presented with, information-wise. The process took merely about a minute.

resize2fs 1.41.12 (17-May-2010)Filesystem at /dev/sda3 is mounted on /home; on-line resizing requiredold desc_blocks = 55, new_desc_blocks = 67Performing an on-line resize of /dev/sda3 to 279054750 (4k) blocks.The filesystem on /dev/sda3 is now 279054750 blocks long.

Very painless!

Before (df -h):
/dev/sda3       865G  7.2G  814G   1% /home

After (df -h):
/dev/sda3       1.1T  7.2G  988G   1% /home

Mount Linux NFS Share on a Mac

So apparently, you cannot just mount "-t nfs" a Linux NFS share on Mac OS X. Credit for this find goes to: http://www.cyberciti.biz/faq/apple-mac-osx-nfs-mount-command-tutorial/

Make sure your /etc/exports are right and then check...

$ showmount -e [nfs-server]

 If all is good, mount with the following command (omit the ",rw" if desired)...

$ sudo mount -t nfs -o resvport,rw [nfs-server]:/[exported-dir] [mount-point]

Detailed USB Device Information from the CLI

I recently needed to get a model number of a Logitech webcam, but it wasn't printed on the device. So I found a neat way to get it from the device itself.

First, run lsusb to list the USB devices on the system. You'll get something like the following:

# lsusb

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 046d:082d Logitech, Inc.
Bus 006 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 007 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 006 Device 002: ID 2109:0811  

Then, run it with the bus and device numbers of the device you want information for... for example, in my case of the Logitech webcam (there's a lot more to it, but I truncated to fit here ~ you may want to output it to a file):

# lsusb -D /dev/bus/usb/001/003

Device: ID 046d:082d Logitech, Inc.
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2 ?
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x046d Logitech, Inc.
  idProduct          0x082d
  bcdDevice            0.11
  iManufacturer           0
  iProduct                2 HD Pro Webcam C920
  iSerial                 1 2D62DFDF
  bNumConfigurations      1

Mounting CentOS 6 NFS on a CentOS 4 Client

I have a CentOS 6 machine that exports NFS shares for various virtual machines to mount and use as needed (mostly to build code on various platforms and architectures).

One of the problem machines is a CentOS 4 VM that mounts the CentOS 6 NFS share upon boot. I fought with this damn VM for an hour before the simple solution hit me. CentOS 4 uses an older version of NFS (nfs?) than CentOS 6 does by default (nfs4).

Here is the relevant line in the CentOS 6 NFS server machine's /etc/exports file:
/home/sm *(ro,insecure,no_root_squash)

Here is the CentOS 4 NFS client VM's /etc/fstab file (the one that does not work):
mndevtest:/home/sm /mnt/smhome nfs defaults 0 0

And here is the CentOS 4 NFS client VM's /etc/fstab file (the one that does work):
mndevtest:/home/sm /mnt/smhome nfs4 defaults 0 0

Literally a ONE CHARACTER change fixed it. I love computers. /s

Fixing the Reboot Command

Somewhere along the line, my Ubuntu 14.04.3 installation (on a Zotac Z-Box) stopped accepting any typed reboot command. It seems to have happened after I removed gnome-power-manager; but even though I reinstalled it, the reboot command still wouldn't work. I'm not sure whether that was the cause, but I think it has a high chance. Anyway, thanks to http://michalorman.com/2013/10/fix-ubuntu-freeze-during-restart/, this little trick worked...

Edit grub's default configuration:
# vim /etc/default/grub

Add the following to the GRUB_CMDLINE_LINUX_DEFAULT string:
reboot=warm,cold,bios,smp,triple,kbd,acpi,efi,pci,force

The kernel will attempt each type of reboot in that order, until one works.

After saving that file, be sure to run the following command to enact your changes:
# update-grub

Reboot your machine, and the reboot command should now work.