Friday 12 December 2008

Another Thing...

Beagle also bit the dust - it's not the performance maiming monster that Windows' background indexing is but I still don't need something chuntering away using power and generating extra flash writes in the background. It is noticeable on a 6-800MHz - grep does the trick for me when I need it.

Wednesday 10 December 2008

U810 Flash

I now have the Transcend 32GB CF card as the main storage with OpenSuSE 11.0 on it - partitioned as 4GB root, 25GB /srv and 1GB swap (to allow suspend-to-disk). Install was relatively painless with the caveats already mentioned. Some things to note...

  1. I plan to use an internal sacrificial USB flash disk (with any luck!) ultimately for swap and tmp space to keep the write load on the CF card down.
  2. To simplify this I have created a tempfs for /tmp so temporary files are written to RAM and then swap - thus I only have to deal with moving swap to USB. To do this, add the following to /etc/fstab:

    none /tmp tmpfs size=1G,noatime 0 0
  3. Symlink /var/tmp and /usr/tmp to /tmp (technically this might be a little suspect in terms of security but this is a personal laptop, not a server)
  4. /var and /home might need some consideration as a whole but not right now
  5. Partitions are ext2 with noatime and noacl to help keep flash activity low
  6. As mentioned before, Transcend 133x CF seems to write at about the same speed as the Toshiba HDD and read around twice as fast. Certainly booting and return from hibernation are noticebly faster.
  7. Power consumption drops quite usefully with the CF card - with the HDD I never saw less than 7000mW (based on KPowersave readins). Now I've seen under 6000mW (with WiFi off) and nearly 6 hours runtime.
I've been rooting round under the bottom panel with a view to fixing an internal USB connector for my sacrificial scratch flash. armed with a multimeter it appears that the second PCI-E connector is not powered up - some fuses are missing but the adjacent power planes are also unpowered. There is, no doubt, something like a regulator that requires a pull up/down to get the power planes energised.

Anyway, looking around elsewhere doesn't turn up a lot of options for voltage sources (I am restricting myself to what I can reach under the bottom panel without further dismantling). I am considering using the SD card power supply voltage since the contacts are easy to reach and Fujitsu has opted for the uppoer end of the SD voltage spec and given it 3.5V.

3.5V should power 3.3V nominal electronics just fine. Many USB devices take the 5V supply and regulate it down to 3.3V immediately. I can either bypass the regulator and run the devices slightly over nominal or hope the regulator can cope with a voltage differential that small (possibly undervolting slightly). Now I just need some nice fine wire...