mikko’s log

If you need to create lots of similar virtual machine guests running on QEMU/KVM, it is a very good idea to prepare a template guest image from which to clone the other guests. You should do whatever customizations you like before cloning. For instance I like to configure LVM and file systems to my liking, install openssh-server, install nfs-common and configure NFS mounts, install all available updates, add users or set up authentication, copy ssh keys, and do many other things so that they will be working out-of-the-box after cloning a number of guests from the template.

After you have installed and set-up your template virtual server to your liking, and would want to start cloning multiple instances of it, some tricks are needed to make things work more automatically after cloning and starting up the final copy.

If you simply clone a vanilla Ubuntu server installation multiple times, you will face some problems:
Read the rest of this entry »

The virt-manager VNC screen is fine for LAN connections, and good for running graphical sessions. X is not installed on Ubuntu server by default, and VNC is really bad over slow links even for text console. I like to configure serial console for all my virtualized guests, because with it, I can simply ssh into the virtual machine host, and run “virsh console <guest-name>” to get a working console. Very nice for fixing broken network connections or file systems, or any kind of boot problems. And I can do it using just my cell phone, ssh over 3G connection from anywhere!

Read the rest of this entry »

My Nokia N900 has the US keyboard with four arrow keys but no diacritics, two of which are used in my native Finnish language. I actually like having the four arrow keys instead of two arrow keys plus dedicated diacritics. You can anyway get those from the on-screen keyboard, but it is better to remap some of the hardware keys to be able to punch them in quicker. Here’s how.

Read the rest of this entry »

Here are instructions on how to get the pware Samba running on AIX 5.3.
Read the rest of this entry »

Here are simple instructions on how to configure network interface bonding on Red Hat based distros. The thing I always forget. There’s also a little script which will create a bonding interface bond0 between eth0 and eth1 and migrate existing IP settings from eth0. You can find it in the bottom of this post.
Read the rest of this entry »

Here’s how to set up relatively cheap redundant iSCSI storage on Linux. The redundancy is achieved using LVM mirroring, and the storage servers consist of commodity hardware, running the OpenFiler Linux distribution, which expose their disks to the clients using iSCSI over Ethernet. The servers are completely separate entities, and the purpose of this mirroring is to keep the logical volumes available, even while one of the storage servers is down for maintenance or due to hardware failure.

Ultimately the disks of the iSCSI target servers will show up as normal SCSI disks on the client (/dev/sdb, /dev/sdc, …). The data will be moved across the network transparently. It is preferable to use multiple gigabit network interface cards on both the initiator and the target, and bond them together for reliability and speed gain (or use Device Mapper Multipath). A separate VLAN for iSCSI traffic is recommended for security and speed. By default, the traffic is not encrypted so your disk blocks can easily be sniffed using tcpdump.

Read the rest of this entry »

I always forget what the correct options for the Windows xcopy command are when I simply want to synchronize one directory over another one. To do it well, you need to remember too many options. And robocopy is never installed when you need it.

Read the rest of this entry »

First, create a key-pair with ssh-keygen. This is a one-time operation.

ssh-keygen -t dsa

It is good practice to enter a good password, but you may also leave the password empty. That will leave your private key vulnerable to local attacks, but if you need to login somewhere from a cron job, you probably need to do that.

Read the rest of this entry »

I upgraded my Lenovo Thinkpad X300 to Ubuntu 8.10 Intrepid Ibex today. My original installation notes for Hardy are here.

After the upgrade, sound was working without compiling an ALSA snapshot by hand. Also, 3G connections worked straight out of the NetworkManager applet, which is very nice. But WiFi was broken, as the nm-applet refused to connect to any SSID, encrypted or open. That seemed to be due to myself using the development networkmanager packages with Hardy. They were not upgraded correctly. The remedy was to remove all network-manager packages and reinstall them. Read the rest of this entry »

I was not able to compile PHP 5.2.6 with IBM HTTP Server 6.1 as a module, so I compiled it as a CGI binary instead. Here’s how to do it. Read the rest of this entry »