Major Upgrade This Evening, Downtime

Both the Linux-laptop I name ‘Klystron’, and the server of this Web-site, this server being named ‘Phoenix’, received a major update this evening. On ‘Phoenix’, a total of 78 packages needed to be updated, including a Kernel-Update, and a Graphics-Driver Update. This collective update effectively converted both computers from Debian 8.7 to Debian 8.8 systems. And both updates appear to have succeeded, at first glance without breaking anything.

However, this was an update that required a reboot for ‘Phoenix’, even though this is my Web-server, and so my site was also down briefly, from approximately 20h40 until 20h50.

I am happy to say however, that ‘Phoenix’ had been running for 58 days straight, without requiring any reboot whatsoever until tonight.

Oh, but I must disappoint some of my readers with the fact that performing these updates also required I restart my ‘memcached‘ service, which means that pages or postings the readers like to visit most often will be a bit slower to fetch, until this server-side caching is replenished.

Dirk

 

The Successful Use of ADB Drivers, to Enable Automation of Power-Saving, on my Samsung S6 Smart-Phone

I happen to be a long-time user of this app, which exports shortcuts to the Android system, which together with this app, allow for the automation of power-saving mode, by way of NFC Tags.

Until recently, this phone still had Android 5.0.2 (Lollipop) on it, which meant that the power-saving app was able to toggle power-saving mode without requiring special permissions. However, since my upgrade to Android 6.0.1 on the phone (Marshmallow), this permission is no longer granted. And so I needed to grant access to the power-saving app, to restricted settings on the phone, via ADB USB Debugging.

Today was the first time I ever used the ADB Drivers on my Linux laptop named ‘Klystron’.

Continue reading The Successful Use of ADB Drivers, to Enable Automation of Power-Saving, on my Samsung S6 Smart-Phone

IRISNotes Digital Pen Again

According to This Earlier Posting, I recently dusted off my ‘IRISNotes Digital Pen’ (not the Version 2), and found ways of synchronizing its internal store of pages with a Linux computer.

I might think that this pen could be a fun toy to play with, if it was not for the high rate of self-discharge of the internal battery, of the receiver. After each day of not being used, the receiver needs to be charged for another 1-2 hours, and after several days of disuse, it needs to be recharged for the full 3 hours again, that are consistent with a completely empty battery. I do not know the reason for this, because even a somewhat ruined battery should not behave quite that badly. But consistently recharging it, does not fix the problem in any way, which remains constant.

If I was to make use of this pen, I would want to be able to leave it in its case, and even take the case with me for several days, and then be able to just take it out of the case and use it. As soon as it needs a 3-hour charge, because I have kept it in its case, it becomes uninteresting to play with.

Dirk

 

Mozilla Printers List continuously Reloads, and alternately shows a Network Printer as Existing and Not.

I recently ran into an error condition, in which on my Linux laptop ‘Klystron’, I had pulled up a Printers List within Firefox, to Print out a Web-page. And the list of available printers kept updating, alternately with a network printer displayed as existing, and with the same printer missing, just over once per second.

I was able to get to the root of this problem.

I had recently installed the package ‘avahi-daemon’ on that laptop, prior to which that error condition did not occur. ‘avahi’ is a service-discovery daemon, which means that it scans the network neighborhood, and makes shared resources visible in the lists of GUI applications, where those resources might normally not be visible under Linux.

The cause of this problem seems to be, that if more than one resource exists by the same name, Firefox will continuously be in a state of confusion, about the fact that both resources should exist side-by-side.

For example, it is possible to have a printer named ‘PIXMA_MX922′, which is a WiFi-printer and which is therefore accessible directly on the LAN, by way of the router. It could be installed directly on all the computers by way of CUPS. But at the same time it is possible to have a server set up which is named ‘Phoenix’, the CUPS service of which has that printer installed directly, as well as having the ‘Samba server’ installed, which offers to share all the local printers as a Samba share by the same name, by default.

Next, if we have a laptop named ‘Klystron’, which is running the ‘avahi-daemon’, then according to its new discovery capabilities, there are at least two printers on the same network,

  • ‘PIXMA_MX922 As installed on the LAN’ and
  • ‘PIXMA_MX922 As belonging to the Samba server Phoenix’

As far as I can tell, the problem here is that both printers will have the same name, because the Samba server serves it out as having the same name it had locally with its own CUPS server. And at that point, the Available Printers List belonging to Firefox becomes unstable.

There is more than one way to solve this problem.

Continue reading Mozilla Printers List continuously Reloads, and alternately shows a Network Printer as Existing and Not.