Grant Williams ASFA 2013 presentation

While this isn’t an economics or investment blog by any means, here’s a nice 30 minute presentation by Grant Williams recently given during the 2013 ASFA conference. Humorous as always and IMHO spot-on, outlining the current state of international financial markets, the current government bond bubble and equity rally of 2013… and how it’s all inevitably going to go down in flames. Very well worth watching, even if you aren’t a investor, trader or otherwise closely associated with the financial markets.

[youtube https://www.youtube.com/watch?v=5A3CoFyi2U8]

Fix for bad write performance with LUKS + RAID5

After setting up a new fileserver with an LUKS encrypted dataset on top of Linux software RAID5 I did some benchmarks and reliability testing before filling it up with “real” data… but it turns out write performance was quite horrible. Only a fraction of what the “raw” RAID5 could do, all while having the CPU mostly idle. So what’s going on?

Apparently only small blocks of data get written to the disks when using LUKS encrypted volumes (mostly default settings) therefore dramatically reducing write performance (figured it out thanks to this) on my RAID 5 volume. Setting the stripe_cache_size from 256 to 8192 increased throughput from roughly 50-70 MB/sec to well above 200 MB/sec.

echo 8192 > /sys/block/md0/md/stripe_cache_size

To permanently set it, so you don’t have to manually adjust it after every reboot, consider setting up a udev rule like this:

/etc/udev/rules.d/md-stripe-cache.rules


SUBSYSTEM=="block", KERNEL=="md*", ACTION=="change", TEST=="md/stripe_cache_size", ATTR{md/stripe_cache_size}="8192"

Fix for Google Play Error [RPC:S-5:AEC-0]

After re-installing the Google apps package (gapps-jb-20130301-signed.zip) on my CM10.1 phone, Google Play stopped working and didn’t let my install any new apps or update existing ones. To fix the Error[RPC:S-5:AEC-0] you’ll have to:

Go to the system settings -> delete your Google account -> add it again and let your Android sync

Don’t worry, you won’t lose any of your data by doing that.

CUPS and Canon Pixma: Printer hangs after first page

After updating my Ubuntu desktop to a more recent release (12.04 / Precise Pangolin), my rarely used Canon Pixma MP190 stopped working. Not completely, but in a rather annoying way: Printing a single page works fine, but printing multiple pages / copies causes the printer to hang. Hard. As in, you have to pull the power plug to reset it, as no button will do anything anymore.

Apparently there was a bug introduced with CUPS a while ago, or rather a change in behavior of CUPS which triggers a bug in the printer Firmware. Took me a couple hours to find and had me on the brink of throwing out the whole printer.

And it looks like it affects quite a few other USB printers as well:  Epson NX130, Canon i550, i560, ip4200, ip4300, ip5200, MP180, MP160, MP210, MP450, MP500, MP520, …

To save you from reading through all the comments: Till Kamppeter came up with a workaround that worked perfectly for me and others.

In a terminal window, run the command

lpadmin -p  -o usb-unidir-default=true

with  being the name of your printer as displayed
by the "lpstat -p" command.

Now turn off and turn on your printer, then try to print several jobs.

 

After that I was able to print a couple hundred envelopes without a hitch.