This is my new small ZFS fileserver.
It was originally going to be a VMware ESXi development server, but after starting on it I decided that I don't need an ESXi server at home. So I started wondering if I could suspend two hard drives and keep the big heatsink in a case this small and use it to replace my large, too-loud fileserver. This is the result.
Specs are as follows:
Case: Lian Li PC-Q07B case
PSU: PicoPSU 120 with 80W EDAC brick
Motherboard: Zotac GF6100-E-E
CPU: AMD Athlon II 240 2.8GHz @stock
Heatsink: Cooler Master H212
RAM: 2x2GB A-Data DDR2-800
HDD: 2x2TB Samsung HD204UI (mirrored zpool)
Boot drive: 8GB Transcend SLC SSD
OS: FreeBSD 8.1
Idle power: 41W with drives spinning (very old motherboard model only supports C1 power state)
Large-file transfer rates: 108MB/s read, 90MB/s write (Linux NFS client)
I'm very impressed with the difference that drive suspension makes. I can't hear the machine at all from more than 18" at the quietest ambient level in my house, although my hearing is not excellent.
Switching from 4x500GB RAIDZ to mirrored 2TB drives has also greatly improved performance subjectively. In particular it handles concurrency a lot better, so that I can do multiple large transfers without affecting NFS homedir response. A big misconception I once shared with many others was that RAIDZ = RAID5 and RAIDZ2=RAID6. They aren't the same and have different performance characteristics -- much better for writes, and much worse for reads. Also RAIDZ performance degrades much worse than mirrors as the pool fills.
The "inside" fan is just an empty shell with the internals cut out, used for a plenum. The fan is a very low-speed model from a Silverstone case. I listened to it and three different Yate Loon D12SL's and felt the Silverstone was the quietest. It's set to just a hair shy of the lowest voltage on the Zalman fanmate. I don't have monitoring working properly yet so I don't know what peak CPU temp is but it idles in the low-mid 30's in BIOS and never seems to get really hot.
There is room to add a third hard drive in the original bracket and/or a PCI-e card, if needed later.
Also this thing was pretty inexpensive to build. Case $60, drives $80 each(!) and board $40, all bought during Newegg's Black Friday sale. CM212 was $25.50 from Amazon, and PicoPSU and brick about $55. I already had the CPU, SSD and RAM. The board is so cheap because it's considered defective -- the board's front USB headers don't work -- irrelevant for this use.