SudoSeth » RAID

tune2fs: Free Space in a Storage Partition

Seth — Mon, 01 Jun 2009 21:03:07 +0000

The ext2, 3, and 4 filesystems by default all reserve 5% of their capacity for the root user. While this is very important for partitions that contain /var or / (the root of the operating system), it can be a waste of space in drives that are only used for file storage. After making a ext4 partition I realized that I didn’t change the default setting. Instead of having 3.6TB of usable free space on my new hard drive I only had 3.4TB. After a quick google search I found an Ubuntu forum posting with a similar issue: http://ubuntuforums.org/archive/index.php/t-215177.html

The command I used is very simple:

# tune2fs -m 0 /dev/md0

Where /dev/md0 is the partition you are configuring. For more help check out the manual page for tune2fs (# man tune2fs )

Ubuntu Installation Issues: RAID

Seth — Fri, 14 Nov 2008 17:27:50 +0000

I set up the partitions on my hard drives the way I wanted. I have dual 500GB sata drives that I wanted to put in a RAID 0 with 2 partitions. 495GB each for the OS and then the remaining space for swap. When I was done configuring everything and wrote the changes to disk, I got the following error:

“The kernel was unable to re-read the partition table on /dev/md0 (Invalid argument). This means Linux won’t know anything about the modifications you made until you reboot. You should reboot your computer before doing anything with /dev/md0.”

This was followed by an identical error for /dev/md1. I’m still not sure of exactly what caused the error, but the quick fix I used was to hit the ESC key after the errors take place, wait for the menu to show up (the computer wants to install the base system first), then without changing anything else, set up the RAID partition that you are installing the OS, and don’t modify the swap partition or anything else like that. When I did this I still got the error for /dev/md1, but I did not get one for /dev/md0, which is what I am installing the OS to.

Another Server Migration

Seth — Sun, 19 Oct 2008 20:58:20 +0000

After several complaints from my family about not being able to access the local network file shares while I was playing video games on my computer, I decided to put all of my data onto the new server “DuckTape”, and move the website back to the old web server. This makes my family happy and really shouldn’t effect the website unless I get hit by digg, but even then it shouldn’t make that much of a difference.

What really prompted moving the hard drives over to the other computer was the fact that due to a hard reboot I lost all data contained on my RAID5 array. Apparently RAID5 is awsome at protecting data from hard drive failure but it absolutely sucks at dealing with power outages and the like. Luckily as a good sysadmin I keep regualr backups. After 17 hours of transfering 1.5TB of data onto a new RAID0 array on DuckTape, I was back in bussiness. The only thing that got lost from the failure was a small portion of an Ubuntu 8.10 Beta .ISO file that was only partaily done downlading when the backup was run. THIS is how easy it is to restore data when you KEEP UP TO DATE BACKUPS.