Zugschlusbeobachtungen

Four days before my wedding, I spent some time researching booting a PC from a large hard disk, where large means "larger than two Terabytes". These days, single disks are approaching this size, so we are near the state where this issue pops up for your run-of-the-mill computer rather than the data store RAID. Today, the per-gigabyte price is however still significantly cheaper if you go for a 1 T or an 1.5 T disk.

The old blog article shows that I spent considerable time in finding out today's limitations below the 2 T limit by using conventional partitioning schemes to boot a 2 T disk. Since I don't have this much storage available at the moment, I had to use virtualization and to take advantage of nearly empty virtual disks taking up much less space than their raw capacity suggests. This works fine as long as you don't start actually using the disk.

Back then, the only combination that worked for a raw disk larger than 2 T (only using the first 2 T) was Virtualbox and grub 0 (now grub-legacy). I regret to admit that the results of my experiments from June are not any more reproducible (most probably due to changes in Virtualbox since then) and that I was not able to boot any disk larger than 2 T any more, even if the partitions were well below the 2 T limit. I chose to ignore these results and to finally start the GPT research.

I recently had to install Openfiler on a HP server with ten 750 GB hard disks on a cciss RAID controller, which proved to be a major nuisance. Since the customer wanted the box in service fast, I finally settled on wasting two of the disks as a 750 GB RAID 1 for the actual system (with like 10 GB actually used) while RAIDing the remaining disks together to a RAID 6 with spare disk for productive data.

During this task, I noticed a severe lack of current knowledge about modern PC architecture and how to boot from a big hard disk and decided to do some research into this direction. This article shows the first "results" that I have achived in the last few days.