Do it Yourself Storage Area Network (SAN)

A 24 disk storage array consisting of the following hardware:

• SUPERMICRO MBD-X7DWN+ Dual LGA 771 Intel 5400 Enhanced Extended ATX Server Motherboard


• SUPERMICRO SC846TQ-R900B storage chassis


• 2 x Intel Xeon E5410 Quad Core 2.33GHZ LGA771 12MB 1333FSB Harpertown Retail Processor


• 2 x 4GB RAM (see all compatible Crucial DIMMs for this board, and see notes below about RAM requirements)


• Areca ARC-1680ix-24 24-port RAID controller


• Areca ARC-6120 Battery Backup Module


• 1 x 2GB cache memory module for Areca RAID card


• 24 1TB SATA II drives (current candidate is Western Digital Green Power 1TB, model Caviar GP WD10EACS)


• 1 x Western Digital Caviar Black 500GB boot drive (this resides on the motherboard controller)


• 1 x 4GB or 8GB compact flash card as maintenance boot device (resides in compact flash slot of motherboard)


• 1 x compact flash adapter (it might be worth it to get several as failsafe bootables)

1. Sufficient memory needs to be onboard for fsck of 20+TB, and large filesystems can consume a large amount of RAM or not work at all without it.  1GB RAM per 1TB storage is a common rule, so running 8GB is a lower limit, not an upper limit.


2. We also need reliable GPT support for this size of an array, which is not there yet on many OSs.


3. X7DWN+ is not listed on Supermicro's BSD compatibility matrix, but people report OK use under Free BSD 7.0 REL


4. A useful discussion about compatible generic memory for the Areca controller


5. Areca manuals, benchmarks, firmwares etc.


6. Drive compatibility with the RAID controller needs to be established. For compatible Western Digital drives this requires adjusting the TLER values in each drive's bios prior to using it in the RAID array. Note the DOS utility rewrites the BIOS of all attached drives, so this should only be done an a system dedicated to this task. Other non-RAID certified drives may need similar adjustments.


7. Western Digital reports the 1TB GP as compatible with the Areca.


8. As of 12 November 2008, only a handful of 1TB drives are certified by Areca and several common ones are explicitly NOT compatible. In the Western Digital line only the WD RE2 GP RAID Edition 1TB is certifed, with SAS controller firmware V1.45 80915 or later. Unfortunately such RAID-certified drives are nearly double the cost of non-RAID variants.


9. Western Digital Green Power (WD GP) drives are only 5400 RPM but reports suggest that differences in read/write performance between hard drive brands becomes less important as more drives are added to the array.


10. A test report of an Areca 1680-type SAS controller


11. This 2GB memory module reported to be compatible with a 1680 controller. Worth getting.


12. Without the battery backup the Areca cards turn off write-caching completely to help prevent data loss.

1. use http://www.shopbot.ca/ to find the lowest price on gear above for price matching purposes. Some items in the SAN parts list are already linked to shopbot.