Iam going to build this based on a series of small posts I've made as I feel much of the information is actually hard to find and piece together from the rest of the web.
What I'm going to focus on is how to use virtio as the NIC because if you don't you get very slow NIC speeds but with the virtio NIC model you basically get host speeds.
/usr/libexec/qemu-kvm -enable-kvm -smp 8 -m 16000 -net user -net nic,model=virtio -drive file=ubuntu-gpt2large.img,if=virtio........
Yes you have that right, the network service in CentOS 8 no longer exists. So there is no more systemctl restart network
You can restart NetworkManager but it doesn't have the same effect or ifup/ifdown on all interfaces.
To replicate that the best you can do is type the following commands to nmcli
nmcli networking off; nmcli networking on
*Don't forget the semi-colon otherwise you'l........
This problem has been around forever, Linux seems to think it is fine to use the r8169 driver for an r8168 NIC but this often causes problems including the link not working at all.
In my case ethttool shows the link up and detected but it simply does not work especially on a laptop that has been resumed from suspension. Sometimes it takes several minutes for it to work or to unplug and replug the ethernet.
Here is the solution:
The strange thing is that usually the first install or two will work on any new machine but then it suddenly won't. I had this experience on QEMU 2.13 on a different machine. There is something finicky or buggy about the CUCM installer even when choosing the same virtual hardware specs.
QEMU PC emulator version 0.12.1 (qemu-kvm-0.12.1.2-2.506.el6_10.1), Copyright (c) 2003-2008 Fabrice Bellard
Idid a systemctl restart networking and it broke Proxmox VM connectivity!
#proxmox is the problem after restarting the network the tap devices go to disabled state
[2230884.919905] vmbr0: port 7(tap118i0) entered disabled state
[2230884.948864] vmbr0: port 8(tap122i0) entered disabled state
[2230884.972748] vmbr0: port 6(tap119i0) entered disabled state
[2230885.004745] vmbr0: port 5(tap117i0) entered disabled state
I've read a few guides about this but they didn't work for me.
sudo apt-get install bridge-utils
#don't think the above is enough it won't work still even though you have by default an /etc/qemu-ifup that handles it if you have the right tools and setup
sudo qemu-system-x86_64 -net tap -net nic -enable-kvm -cpu host,vmx=on ~/VirtualBox VMs/vsphere-vcenter/vsphere-vcenter.vdi
W: /etc/qemu-ifup: no bridge for guest interface foun........
It all comes down to a bug essentially where you are running an older kernel that doesn't support the newer Debian templates. The solution is to update your OpenVZ kernel.
Here are some symptoms of the problem/lack of kernel support:
Ubuntu Template 12.04 requires a manual network start:
service networking start
sshd will not start:
PRNG is not seeded
mknod /dev/random c 1 8........
It sounds like this is corrected in later versions of the OpenVZ kernel but Iam not sure, it may also be that a much newer kernel is needed and Centos may not have a recent enough kernel.
*Debain 7.0 however does work fine as a temporary fix or work around.
Debian 8 OpenVZ no IP and networking not working:
lo Link encap:Local Loopback
Thsi is very handy when doing your own kernel development.
-m specifies how much ram (in the example it is 768MB)
-kernel specifies the path to the kernel file
-net tap,ifname=tap1,script=no (the ifname=tap1 is what you need to change and setup manually).
*Run "tunctl -b" to create a tap device and use the one it gives you for ifname=
Enable networking to the outside like this:
*Note we assume that your bridge is br0 i........
./configure: line 91: cd: /lib/modules/2.6.32-042stab084.25/build: No such file or directory
Error: kernel version not found.
Please make sure your kernel is configured.
dr-xr-xr-x. 4 root root 4096 Feb 21 06:13 ..
lrwxrwxrwx 1 root root 45 Feb 21 06:13 build -> ../../../usr/src/kernels/2.6.32-042stab084.25
drwxr-xr-x 2 root root 4096 Feb 12 20........
If you move your hard drive(s) around to other computers/servers, you'll find that your eth0 keeps getting higher, the first time it will become eth1 and then eth2 etc and even higher if your server has dual or quad NICs. The reason is that udevd basically assigns eth0 tot he first NIC it finds and remembers it, if it encounters a NIC with a differentMAC, it assigns it one higher (eg. eth1).
See the example below, I have eth2 now so how doI fix it?........
My mother needed a new laptop and I recommended her the same one I would have bought myself or my wife, that means the cheapest possible laptop with the most features for the money.
This HP shines at this price point and one thing that made me stay away from buying more and recommending HP/Compaq was the poor battery life. Not anymore, this model has an industry leading up to 4 hours of battery life.
Key Factors for Choosing It:
I've never understood how to enable and disable services for different run levels in Debian based distros, it's just weird, annoying and doesn't make sense. I much prefer chkconfig from RHEL.
Just install the package called 'rcconf' and be done with it. rcconf makes things easy for you.
apt-get install rcconf
Reading package lists... Done
Building dependency tree
Reading state information... Done........
We've noticed in many ways that traditional networking even in WANs and LANs has changed very little. Years ago most networks were running on 100mbit and today most still are.
Even the average internet connection is largely unchanged from several years ago with some minor exceptions from Europe and Asia.........