Project: Building a cheap NAS, part 4

Filed Under (Windows Networking) by Just An Admin on 02-05-2011

Part 4: The final parts

Almost there! We are still in need of some parts that are required to get our cheap NAS running; The power supply, cabling for the SATA connections and a little, extra ‘gadget’.

The power supply

We need a good solid power supply that can handle the power required to spin up our disks, and also be able to support future expansions. So at least 20 disks and three controller cards on a I3 processor motherboard. We kind of went solely on borrowed knowledge here. We were advices to look at the Seasonic OEM 750W ATX EPS SS-750HT 80Plus Silver DC-DC.
Noise isn’t really a factor with all the noisy fans in our Norco chassis, but the fan in this power unit is very quiet (25dBA). If you want to supply all your backbones in a 20 disk chassis, you may need to get a few SATA to 4 pin female converters. The power connectors that come standard are very diverse, and offer more than enough SATA, ATX and PCIE connectors, but 4 pin connectors are underrepresented.  You need two to three 4 pin connectors for the Norco chassis fans, and a minimum of 4 connectors for the SATA/SAS backplanes. The power supply provides you with 6 of these 4 pins connectors.



This power supply costs us: 118 euro

The cables

We have purchased an Intel SASUC8I internal SATA controller and plan to use the on-board SATA ports of the motherboard to connect a total of 10 disks (potentially 14 disk using all controller connectors). Since the backplanes in the Norco casing uses a SFF-8087 connector for each 5 bay backplane, the Intel SUSAC8I uses the same SFF-8087 and the onboard controller uses the regular SATA connectors, we need the following cabling:

  • 2 x SFF-8087 to SFF-8087 Internal Multilane SAS Cable
  • 1 x Discrete SATA to SFF-8087 Mini SAS Reverse breakout cable aka reverse breakout cable

Total costs: 47 euro

Note: After connecting all the cabling , we will have three of the 4 backplanes connected. This if good for 12 disks and more than enough for our 10 disks.

A little extra ‘gadget’

To enhance the performance of our DIY NAS server, we were advised to look at the ZFS filesystem and the use of L2ARC cache aka cache disk in the form of SSD. There are two types of cache that can be performed by an SSD disk that would greatly benefit performance: ZIL cache and L2ARC cache.

Excerpt from constantic.glez.de about L2ARC cache:
ZFS has a sophisticated cache called the “Adaptive Replacement Cache” (ARC) where it stores both most frequently used blocks of data and most recently used ones. The ARC is stored in RAM, so each block of data that is found in the RAM can be delivered quickly to the application, instead of having to fetch it again from disk. When RAM is full, data needs to be thrown out of the cache and is not available any more to accelerate reads.
SSDs can be used as a second level cache: Blocks that can’t be stored in the RAM-based ARC can then be stored on SSDs and in case they’re needed, they can still be delivered quicker to the application than by fetching them again from disk. An SSD that is used as a second level ARC is therefore called an L2ARC, or a “cache device”.

L2ARC cache would greatly benefit:

  • Throughout: read performance should greatly benefit from this cache
  • Total IOPS will become higher due to this fast cache
  • Steady throughput,: It will level out peaks and drops in  the throughput

Using SSD disks as ZIL cache on top of the L2ARC cache would be an even better performance enhancer, but it is strongly advised to use two SSD disks in mirror as ZIL cache and that would make our setup to expensive for now, although we may look into partitioning (slicing) our SSD disk in a SIL and L2ARC cache.

As IOPS is one of the factors we want to boost, we are looking at SSD disks that offer the best IOPS at the moment and performs at the top of the SATA-II specs. Not all vendors offer the IOPS specifications on their basic info page, but some reading and searching has let us to believe that we should go for the OCZ Vertetx 2 60GB SSD disk. With a sustained write speed of 250MB/s and a total of 50.000 IOPS on 4k aligned random writes we should be burning rubber.

This little extra costs us another 98,- euro.

The shopping list

We now have completed our shopping list and have ordered all our parts. Time to see what the damage is:

 

  • Norco RPC 4220 chassis: 435,- euro
  • SuperMicro X8SIL-F-O motherboard: 165,- euro
  • Intel i3-540 processor with
  • 8GB memory kit Kingston: 119,- euro
  • Intel SASUC8I SATA controller: 119,- euro
  • 10 x WD Green Caviar 2TB disks: 720,- euro
  • High speed USB stick 16GB Kingston: 28,- euro
  • Seasonic 750 watt power supply: 118,- euro
  • cabling: 47,- euro
  • OCZ Vertex 2 SSD 60GB: 98,- euro

Grand total:       1849,- euro

That is a very acceptable bill to pay for 20TB of raw storage and the potential to offer even more. But so far we have not used a single bit of it. Time to wait for the orders to arrive, put the parts together and take it for a spin…..

To be continued!

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