RAID, Glorious RAID

I'm not sure what made me think of it, but two days ago, I decided to convert my computer to using a RAID array.  Unfortunately, that means I lose all my existing data, but that's ok because I can download it all again.  It's open-source software, after all!

I scrounged up three 250GB Western Digital Caviar drives (unfortunately, they're 1.5Gb/s drives) and a 500GB Seagate Barracuda drive (3 Gb/s).  I left the 250GB drives in one large partition each, and I split the 500GB drive in half, creating two 250GB partitions.  Well, actually 3.  250GB went toward the array; 246GB went toward a partition I called /store; 4GB went toward my swap partition.  I don't recommend swap space normally, but I run lots of IDEs, VMs, and other memory intensive applications.  I run into my 4GB of memory really quick, so another 4GB is about what I need.

I tried using hardware RAID.  Since I have a nice, cheap-o motherboard, it's fakeRAID, which is just glorified softRAID that Windoze can use.  But, unfortunately, Linux didn't play nice, so I ended up using softRAID.

Now comes the time during which you choose the type of array you want.  I chose RAID5 because of its speed and redundancy.  If a drive fails, I panic, but then I replace the drive and all is well again.  With RAID10, half of the drives can fail at the same time and it'll still work.  But it's slightly slower.  There are benchmarks online that compare softRAID speeds RAID5 vs. RAID10.  Then there's RAID0 (mirroring), which only works with two or more drives, but half of your drives can fail.  RAID1 (striping) gives you no tolerance for failure, but you sum up all the space on your drives into one lump sum.  If one drive fails, you lose all your data.

I reinstalled Ubuntu, using my softRAID5 array.  Installation took longer than I expected, but then again, I've never installed Ubuntu using the "alternate" installer.

Now for the completely-biased benchmarks.  Originally, I could read about 50-60MB/s off of a single 250GB Western Digital Caviar SATA1 drive.  In the array, I peaked at 161MB/s and averaged 120MB/s.  That's nuts for a bunch of old drives!

Unfortunately, I couldn't test write speed yet.  I need to find a better benchmarking application than the default one in the Ubuntu Disk Manager.

More info on RAID arrays on Wikipedia.