Work has a Red Hat Enterprise Linux box for R&D to use. It does boring stuff like CVS, Apache/Wiki and some issue tracking thing. It was deployed on a second-hand box with plans to migrate it to a new properly specified box later on. As with all projects of this nature it has outgrown available space and was becoming constrained by disk space.

Because we didn't have spare NFS space for it, we decided to replace the two 18Gb hardware-mirrored disks with a pair of 36Gb disks. The only snag with the plan being that the chassis only had spaces for two disks.

Yesterday we had available a beefy box with lots of empty SCSI bays, so using a KNOPPIX live disk and the "tar trick"^[1] we created new larger file systems, and copied the content over from one pair to the second. It all went surprisingly well.

We then put the new disks back in the original chassis and booted with DSL (2.6 kernels like KNOPPIX won't boot on Compaq DL360G1 systems). Everything looked okay, I chrooted to the new filesystems, and did a grub-install and rebooted. Grub started, the kernel loaded, but it refused to mount anything read-write and dropped us in as root.

After lunch and some googling we discovered that KNOPPIX had created ext3 file-systems with features that the fsck on the RHEL3 did not support. It wanted to do an fsck before the mount, couldn't and stopped the boot process. We turned off the features with debugfs, and RHEL3's fsck was happy. Everyone was happy and the R&D engineers now have another 20Gb of CVS space.

1. LinuxHints / One Disk To Another