Wednesday, 30 November 2011

Hotswap IDE bays

One of the things I need to do a lot with building and repairing computers is to remove a hard drive and attach it to a second system to do an offline virus scan or attempt to recover data. For SATA drives that is easy, I have a couple of eSATA docks which allow me to slide in any SATA drive without a problem. As SATA hotswapping is not a problem (at least with AHCI mode in the BIOS), this allow me to boot the known working system and get the virus scanner an everything up and running before attaching the drive. Hopefully this should detect any bootblock issues etc.

I still have need to test IDE drives, and they are more of an issue as I either have to dismantle the second PC and connect it internally, which means it is present during boot which isn't ideal, or I have to mess around with USB-IDE adapters and external power supplies which isn't ideal either as it is a bit of a faff and is limited by USB speeds. I got a couple of removable IDE caddies which improved things as it made it easier to connect to the PC, but still meant I needed to have the drive present during booting.
So the idea I had was to use a couple of IDE-SATA convertors. These little boards allows you to use SATA drives with an IDE host or, as in this case, use IDE drives with a SATA host. I did some testing with the drives powered up all the time, and connected via the adapters to the SATA ports on the motherboard and they were detected fine and accessible at full speed. All that was needed now was hotswap capability.
The caddies have a key operated power switch, which cuts power to the drives to allow removal. The SATA-IDE adapters only need 5V (usually provided by a 3.5" floppy power connector), so I found the switched 5V line on the back of the caddy and wired it to the SATA-IDE adapter power so it would be switched on and off with the drive.
Now for the test. Power it on before boot to check it all still works, yes, no problem. So now I booted with the key turned off, and once booted, turned they key on. The drive spun up and was detected just as if I had slid in a SATA drive. I then made a second to complete the pair and now use these regularly for testing IDE drives.

For Data Recovery or Virus problems, see Tynemouth Software LLP

Wednesday, 9 November 2011

Home Theatre PC

I have an existing HTPC that does fairly well with an Asus board with an Atom / Ion, and handles full HD acceptably well thanks to VDPAU support in MythTV. I now need another one, so I've been looking around at the options. The Atom / Ion boards are still there, as are the AMD Turion's as so on.
In looking around I found a few fairly reasonable Sandybrdige boards with the H61 chipset. This seems to be a cost reduced version of the H67, and is missing a couple of PCI Express lanes and SATA 6GB/s ports. So I looked at the 1155 process options and the until the Sandybridge Celerons are released, the Pentiums seemed to fit the bill, again fairly reasonably priced compared to the i3 series, but with a few features missing. The important ones like the onchip Intel HD graphics and the memory controller which gives Sandybridge such high memory bandwidth.
So I went for an Asrock H61M-ITX board and an Pentium G620 for just over £100, add 4GB of DDR3 memory and that took it to £120, which I think is less that the Atom board cost a couple of years ago. Performance wise I was very impressed, with better memory bandwidth scores than my i7 950!

I went for the same case as the previous one, a cheap unbranded ITX case with a 250W PSU. I quickly decided to make the same modifications to the case as with the previous one, namely getting rid of the two noisy fans. There is an 80mm fan on the front and a thin 80mm fan in the PSU.
The heatsink on the G620 gives a fair indication of the amount of heat likely to be generated, so I don't think they are both necessary. As the PSU fan is the 10mm thick variety I didn't want to replace it with the same type, so I used a normal 80mm fan outside of the PSU case, using the original mounting holes, but from the other side. The three pin fan header could then be connected as a chassis fan and speed controlled by the mainboard BIOS.
I also took the opportunity to remove the 3.5" hard drive cage as I was using a 2.5" SSD. Since the front fan was no longer present, I bolted the 2.5" SSD in its place, and also attached a couple of internal USB ports in front for the wireless keyboard / mouse receiver. It isn't the best, but putting it behind a big metal box doesn't help, so out in front, there is only plastic and air between it and the keyboard.
After a painless install of Mythbuntu 11.10, it found my myth backend and I was watching HD TV again in no time.