Computer systems that run the telescopes, store data, and provide remote analysis for users are currently built in house from standard components selected for the best performance/price ratio. The selections here were initially made in Fall 2014 and have been working well since then (currently January 2018). The main servers mtkent1 and mtkent3 which archive data were replaced in 2017 with Supermicro servers. Typically useful lifetimes for hardware before failure or obsolescence is 3 to 5 years though recently these systems have been more reliable, with only one failure out of about 12 attributed to environmental heat stress. Nevertheless, computers at the telescopes may be smaller modular fanless units where proximity to electronics such as cameras, filter wheels, and focusers prohibit long cable runs.
The Supermicro 2U rack servers accomodate 6 to 8 hot-swap SATA drives. The older ones remain in use still have a and 1 full height DVD and a single 400 watt power supply, but newer ones are built without the DVD and with dual redundant power where it is critical.
This and other 4U servers are available from Servers Direct assembled with motherboard and processor of choice.
Used for telescopes and operator consoles, these can be built economically in house. The data here are from late 2014. The parts selection may be different now, but costs will be similar.
Corsair Obsidian Series Black 550D Mid Tower Computer Case $117
A large case provides exceptional ventilation, ease of access, and quiet operation. USB3 is brought out to the front panel. The interior has many slots for SATA drives and for two full height DVD drives. If rack mounting is not required, it will work splendidly as a server enclosure especially for systems with GPU cards that require high power. The SATA drive carriers do not use screws, and while the drives are not hot swappable, it takes only minutes to replace one without tools.
Alternatively, for Supermicro motherboards their mid-tower chassis is smaller and comes with a power supply for about $130:
The Corsair power supplies have been reliable and are quiet. A typical one is the CX600 available for about $66.
Power supplies for the observatories have to be quiet, and should be green with high efficiency. Typical lifetimes have been 3 to 5 years, but some supplies from Antec have had premature failure and are not recommended.
The best CPU is selected at time of purchase based on price, availability, and Passmark ratings from this site:
As of November 2014 the preferred solution is a Xeon E5-2620 V3 6-core LGA2011-V3 socket CPU running at 2.4 GHz and 85 W with a Passmark rating of 10,743. It is available from Amazon for $446.
These boxed CPU's are supplied without a cooler which is purchased separately. We use the low cost air-cooled Intel Thermal Solution Air $36 The cooler runs quietly, and is not at risk for use at a telescope where there may be temperature extremes.
We have had good success with motherboards from Supermicro. Currently there are more than 10 in service, some for two years of continuous use. We have had three failures in two years. One was in a system exposed to environmental extremes, and a similar one was in a controlled environment. Both failed after a power disruption even though they were on surge-protected circuitry. The problem could have been with the motherboard itself, or due to a spike from the power supply. We have not had a failure with the preferred power supply noted below. With any case and a recent motherboard it is necessary to check that the supporting stubs match the available holes and that there are no unused stubs without a matching hole.
Supermicro X9SRA Xeon and I7 supports 512 GB of DDR3 memory in 8 sockets, and offers 2x PCI-E 3.0 x16, 1x PCI-E 3.0 x4 (in x8), 1x PCI-E 2.0 x4 (in x8), and 1x PCI-32. It is available through distributors offered by Amazon for about $275. This board has built-in audio, no video, 4 USB 3.0 ports and 8 USB 2.0 ports from the rear of the chassis, plus 2 serial ports on a header.
The newer Xeon E5-2600 systems require a different socket, and the Supermicro X10SRL-F is preferred.
For the current Xeon E5-2600 processors, the LGA2011 socket motherboard requires 2x or more 8 GB registered ECC DDR4 modules. Crucial memory costs approximately $260 for 16 GB.
There is a requirement to use non-ECC memory with I7 processors but when upgrading computers at telescopes we are switching to Xeon processors with ECC.
Hard Disk Drives
All new drives are Seagate Enterprise (formerly Constellation) class SATA drives.
The 4 TB drive was the cost effective choice in 2016. In early 2018, an 8 TB drive was the same ~$200 price and is being used for replacements and storage upgrades. Allowing 6 slots at this capacity provides 48 TB online, exceeding our current needs for several years.
Note that the commodity Seagate Barracuda line is not as reliable and has had in our uses an MTBF of about 2 years. We have not had only 1 Enterprise drive failure since implementing them in 2012.