Book of the month – Linux Server Hacks

Gili Nachum — Mon, 30 Jun 2008 00:39:02 +0000

I just read through most of O’Reilly’s Linux Server Hacks book.
I expected another dull Linux how-to book, which goes over the man/info of the most obvious commands, but instead I found an interesting, original, advanced hardcore book, full of Linux goodies to brag about in front of my colleagues.

Some note worthy items:

A thought effective usage of SSH, especially as a secure channel for moving bits around the network, between a pair of processes each running on its own host.
How to reset your root password, without a rescue disk, using the LILO boot loader.
I didn’t knew about ext2/3 chattr and lsattr before reading the book…
Periodical rsync runs could save a lot wasted scp time.
(#44) burning a CD over the network using a pipe – cool
(#50) setting up a VPN using IPIP tunneling
(#57) lsof – hey, I’ve been using it for years.
(#63) loved to learn that the send_arp utility can help me to revoke all of the subnet’s machine (and router?) IP->mac mapping. Handy when setting up a two bits IP fail-over system.
(#68) ssh-agent – now I know what it is – very useful in the hands of an all mighty admin ruling over hundreds of minions machines.
(#73) loved the one-liners perl scriptlets.

To conclude, a must have in your bathroom library.

VMWare: converting a hosted VM to a hypervisor VM – Linux troubleshooting

Gili Nachum — Sat, 28 Jun 2008 12:48:48 +0000

When using the VMWare convertor utility to convert between VmWare player/Workstation/server VM images to an ESX image, if the VM you are converting is Linux you might run into boot problems (“kernel panic” message) due to SCSI drivers problems.

I found a couple of resources about the problem but none fully worked for me, here is my special recipe:
The configuration I used was: RHEL 5.1 VM, and ESX 3.x server.

Use the converter to load the image to the ESX
If you will start the converted image on the ESX you will see a kernel panic message
Go to VMWare infrastructure client -> ESX server -> vm props -> hardware -> SCSI controller -> change from buslogic to LSI Logic
Load the vm CD-ROM drive with RHEL5 install disk (also serves as a rescue disk)
Boot the VM from the CD -> when prompted, enter: linux rescue
The rescue disk should identify the linux partition and mounts it on /mnt/sysimage
After getting a prompt enter: chroot /mnt/sysimage
Backup, and then edit /etc/modules.conf, add this line: alias scsi_hostadapter BusLogic
Backup the current ramdisk file: cp /boot/init-[version].img /boot/init-[version].img.bak
Rebuild with new module and overwrite existing: mkinitrd -f -v /boot/initrd-[version]-img [version]
Reboot the OS.
Boot from the hard drive – The system will start normally

Weird that VMWare do not bother with their official proper documentation.
Kudos to the vmware user community!

Java Tuning » linux

Book of the month – Linux Server Hacks

VMWare: converting a hosted VM to a hypervisor VM – Linux troubleshooting