Archive for June, 2011
I purchased 2 WDC WD20EARS-00M drives and raided them in a RAID 0 configuration (124 KB Stripe) for performance of non-crucial operations. Meaning, anything I have on there I can live with losing OR have backed up at least twice elsewhere. This includes virtual machines, movies and music. Anyway, I wanted to post these benchmarks using HD Tach as there have been a ton of reports that these drives are no good in RAID configurations. They’re probably true, especially since these drives have variable spin rates, which fluctuate independent of each other and can pose problems.
When I first set them up I noticed HUGE fluctuations and large differences in transfer speeds. From 200+ MB/s to ~80 MB/s. I could not duplicate them (not yet at least) but the HD Tach results are promising. Let’s see how this works out. I will update if I have any problems.
The first 3 images are the RAID configuration, with the last being a single drive.
NOTE: I was unable to utilize HD Tune Pro 3.5 to test the raid configuration as it only showed the drives at 2199 GB and reported read speeds of 12460.9 MB/s. There’s obviously something wrong there, probably caching on the RAID controller and within Windows Server 2008, and the fact it’s over 2TB.
UPDATE: I upgraded to HD Tune Pro 3.6 and it is able to benchmark the configuration. It shows that performance ranges from 250 MB/s to 80 MB/s at the end of the drives. Which is great, it’s roughly twice the performance of a single drive, which is what we expected. I also posted the Random Access benchmarks for the single and raided drives. You can tell which is which by the drop down list in the top left hand corner of HD Tune Pro.
The low IOPS on the RAID configuration shows that these drives are not intended for high I/O environments, such as a web server or SQL Server. They do, however, work just fine for low – medium I/O file servers as the good sequential read speeds are perfect for that kind of work.
I will be doing this configuration on my test machine very soon since my previous guide (here) is a bit outdated. For now you can follow the previous instructions and modify them per the instructions below:
The problem is known and posted on many forums.
My solution was:
- Encrypt Windows7 system partition using truecrypt, selecting Single boot and overwriting Grub2 loader with truecrypt loader
- Boot Debian from Rescue CD and install grub2 bootloader NOT on MBR but on /dev/sda3 which is Debian / partition (so truecrypt loader was not overrided)
Now while booting truecrypt bootmenu is shown and if I’d access Win7 I’m entering password, but if I’d enter debian (via Grub2) I hit esc key and then truecrypt loader is searching all other partitions for boot loader and finding Grub2 which resides on /dev/sda3 and load system properly.
I think its the best way to do this for now (until sb find resolution for Grub2 to read /boot/truecrypt.mbr without errors).