As a lot of people are coming to my blog to read the installing instructions for Debian on the GuruPlug Server Plus, I shall not hide my opinion about it: It is a major design and QA fail. Don't waste your money on it.
The power supply
Although I've ordered the Guruplug pretty early with the promise, that I'd have it in April, it arrived at the end of May due to QA issues with the power supply. While I appreciate that they didn't deliver broken power supplies, I would have preferred not to receive one which was "fixed" by somebody who uses the soldering iron like an axe. Here are some macro photos to show the gory details:
The version of UBoot which shipped with the device was only able to boot from NAND and network. Booting from USB failed and ext2 support was missing, too. Didn't have a look if the community came up with a fixed UBoot version yet, but in my opinion a piece of hardware for >100 EUR should not have such flaws.
Using the Guruplug with more than one 100 MBit/s connection is just not possible, as it would toast itself to death. For the details have a look at this discussion in the NewIT forum, it links to a lot of interesting photos and postings. This issue is a major design and QA failure. Even without knowing what the datasheets say, it is easy to imagine that a thin piece of alloy is not the proper way to cool a CPU and network chip. Especially not when it is mounted with cheapish pads instead of a proper paste.
As it seems the plan was to send the heat to the shielding of the network/USB/eSata ports (the area is marked red as my first plan was to remove that part of the alloy and reuse the heat-spreader), a strong indication for that is that this is the only area with holes for air circulation. I could imagine that it was not possible to have these holes next to the PSU, which was mounted above the heat-spreader, to avoid electrical shocks.
As there was no other opening for the heat to leave the case, even the microSD card became pretty hot - I've measured temperatures around 60 deg. C next to the card - while CPU and 100MB/s network were idling.
The official information from GlobalScale Technologies is that only 10/100MBit/s should be used as workaround to avoid overheating until a "Professional Upgrade Kit" is released. As mentioned here the upgrade kit announcement was removed silently from GST's website. To be honest, this doesn't make me wonder. There is no way to fix the Guruplug with an external fan or any other external magic as the only way to fix it is to cool the CPU and networking chip properly.
There are various workarounds for the cooling issues posted to the forums. I've decided to rip out the power supply and heat spreader out of the case and get a nice external PSU. The new connector is mounted, ready to supply the GuruPlug's board with power.
Currently I'm waiting for the new heat sinks and glue to arrive. Then I'll give it a try to mount eveything in the small case again, probably with some additional air holes. As soon as I have a workign solution, I'll blog about it again.