BORG Backup — Deduplicating Archiver

The documentation is very usable, easy to understand. Getting the basic things going is very easy. The code is on github.

It’s worth taking a look and having a go at it! You do know that you NEED a backup, don’t you?!?

I’ve been using dirvish (rsync based) for a good 10 years now. Once set up it is very reliable and can be expanded via pre/post server/client scripts (e.g. to calculate MD5-sums for everything). It supports file-level deduplication (using hard-links), but sadly that doesn’t help with large files that have changed only a tiny bit (like virtual machine disk images). Calculating MD5-sums takes quite some time, especially so as it is done on all backups, so the file-level deduplication saves disk-space but doesn’t help with the MD5-sums being recalculated all the time (on the very same data). A very time-consuming nuisance. Dirvish’s BIGGEST advantage from my point of view however is that the data is easily accessible, it’s just stored in the filesystem you choose (e.g. EXT4). There is no file-level encryption or compression, any system that can mount EXT4 can access the data. Today that is basically any Desktop linux out there.

Back to data deduplication. BORG on the other hand only calculates checksums for NEW chunks of data, so the process is very fast if only little has changed. Yes, I said chunks of data, not files. BORG chops up data into chunks, so it can even handle very large VM disk-images and save some space backing them up. BORG also supports archive compression, password protection and encryption. This immediately brings up the question of long-term accessibility of the data. You really really don’t want to end up with an old backup but vital backup that for some reason cannot be read anymore by new versions of BORG. Fortuitously the developers have released stand-alone versions (see github) that only have minimal requirements (a few standard libs). So far I’ve checked whether these binaries run on a live version of linux (PartedMagic 2015-01-13) and I’m glad to say that the answer is yes. That way it’s quite easily possible to pack a known-good OS / BORG combination onto an USB stick (or ISO image) for future use. In case of a backup that is not based on plain filesystems, it is absolutely VITAL to go that route.

Make a backup, use checksums, verify its integrity, make sure you can access it and restoring actually works. BE PARANOID about your data.

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Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet

Some time ago I wrote about said paper. To be more precise, I didn’t write about the science per se (not my area of expertise), but I wrote about having had noticed an error in it.

I tried to get in contact with the author, which remained fruitless.

At the end of September 2015 I pinged a staff member of the “EJCN” (European Journal of Clinical Nutrition) about said issue. I didn’t hear back from them either.

Today I checked the paper’s page on EJCN and what do you know, there’s a correction [SHA1SUM]. It appears it was released in December of 2015, which is a decent response time. A lot can be said about journals & “peer review” etc. etc.

This time complaining was beneficial. If You find errors, complain as well. Please.

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YOUYUE 858D+ hotair station — Release V1.45

A small but helpful upgrade, if you’re into acquiring your own temperature calibration data. At some undetermined time in the future this might be expanded to a full multi-point calibration mode.

The config menu was amended with the parameter ‘display_adc_raw’. When this is set to 1, the display will show the raw ADC numbers. Temperature regulation is not affected by this, everything else works as usual.

With the help of an external high-temperature probe, you can now quite easily create a table of raw ADC reads vs. temperature measured where you need it, e.g. at the exit of the nozzle (of a certain diameter, for a certain fan speed).

For my device, this looks like this:

Youyue858D-plus-V1.45-temperature-calibration

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YOUYUE 858D+ hotair station — Bugfix release V1.44

I’m glad to announce that the annoying watchdog issue has finally been fixed. It was a dumb error on my side, combined with a prevalence in some ATmega chips to have certain binary values in uninitialized registers after a cold start.


release 1.44

* Fixed “.init1” mistake –> watchdog_off_early.

Putting that into .init1 doesn’t work, as it requires R1 to be ZERO.
“eor R1,R1” comes later, so it blows up.


V1.44 release on Github.

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The day the Twitter died…

I case you haven’t noticed yet, TWITTER IS DOWN, oh no!

First I suspected my friggin’ Android-Tablet, as usual (and rightly so). It is slow and crash-happy, I suspect very poor quality FLASH-memory (IOWAIT is insanely high, fstrim doesn’t do anything, factory-reset is useless…). When funds allow it some time in the future, I will destroy it and shoot a nice YouTube video of me going crazy with a heavy iron object. Am I rambling again? Sorry…

Back to Twitter!

It’s still down, ARGH ARGH ARGH.

I wonder how I would feel should Twitter finally be going the way of the dodo some day. I suspect a feeling of great loss would follow. Yes, there is a great deal of drivel & nonsense on there (I’m guilty as well), a great deal on purpose I guess, BUT at least for me personally the the SNR (*) makes it totally worth it. I don’t know any of my Twitter acquaintances face-to-face, but I’d miss the whole lot of them!

Somehow Twitter seduces its users to being extremely informal, even with people like “Richard Dawkins”, and more often than not you even get an answer of some sort. Sometimes I get a niggling thought that I’m doing something forbidden ;-)

STILL DOWN! [Tue Jan 19 13:31:18 UTC 2016]

2016-01-19__twitter_down

No use continuing this for now…

Well, “Back To The Bench”!

(*) Signal to Noise Ratio

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Happy New Year 2016

PBF111-Reset
PBFComics – RESET

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2015 — What a year!

The year twenty-fifteen has had a lot in stock for me and my family, both near and far.

There was death, illness, strenuous recovery, unexpected relapse, and much other crap nobody really wants nor needs. “A bit much” you could say.

So, today, I’m extremely glad to be finally able to say this:

FUCK YOU 2015!

Good riddance…

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Insidious back-stabbing planned obsolescence — SNAFU

I needed a new shopping basket. The old one had broken down after many years of abuse. In the process it killed a cheap bottle of red wine, which made a nice big puddle on the floor, much to the delight of the shop’s staff. Fortunately the incident didn’t cost me anything.

The replacement looked pretty much the same as the old one and cost 4€. It looked sturdy enough.

I was wrong.

IMGP13290

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PartedMagic — Booting ISO image from GRUB2 / openSUSE

Please note: this is not an excuse not to have a bootable USB-stick for true emergencies. This is just for convenience.

File download

On openSUSE (13.2), this file needs to be placed into “/etc/grub.d/”. After that run “yast2 bootloader” to update GRUB2’s config file (“/boot/grub2/grub.cfg”).

The ISO-file must be on a partition / file-system that is accessible to GRUB2 during boot. In this case the file(s) are on the first partition of “hd0” (defined in “/boot/grub2/device.map”), the boot-partition (EXT4) of this system.

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Low Carb Cheese Cake — yet another attempt

Don’t worry, this blog won’t transform into an adulation for pastry and the likes. At least not for pastry coming from conventional bakeries with tons of sugar and seeds of grasses.

IMGP13260

! LET IT COOL AND REST IN THE FRIDGE FOR 24h !
! MUST BE SERVED WITH EXTRA WHIPPED CREAM !

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YOUYUE 858D+ hotair station — BLDC Fan-speed mod

I’ve finally forced myself to layout a small board. It’s been far too long anyway.

It consists of these building blocks: reference voltage, comparator, RC low-pass, gain.

There are better methods for the job, e.g. using a digital one-shot to create pulses independent of the triggering waveform… yes. As usual I just wanted something that works in this special case, something simple, small and cheap.

youyue-858d-plus-fan-speed-mod__schematic
[PDF]

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Error U81 — Panasonic DMR-EX75 repair

IMGP13174

Some explanation:

U81

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Some old 3D design — memory lane

Just images and 2 short videos.

V2_3c

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Is it just me or is there something wrong with those number?

If you are so inclined, please have a look at this. No electronics of any kind, but a scientific publication about diet / nutrition.

“Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet”, LA Frassetto et al., EJCN, 2009, 63, 947-955, [PDF], [SHA1]

In essence they’re comparing a “usual diet” with a “paleo diet” with respect to all sorts of metabolic parameters, among these are: blood glucose and insulin levels.

From the abstract (emphasis is mine):

“We performed an outpatient, metabolically controlled study, in nine nonobese sedentary healthy volunteers, ensuring no weight loss by daily weight.”

I’ve just skimmed the paper, and got stuck on page 5, table 3 (click to enlarge):

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Fawlty USB3.0 controller card — DC-DC noise?

Well, this won’t make it any easier! Not at all…

IMGP12980

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Fawlty USB3.0 controller card — quick DC-DC regulator check

This card is pretty good, when it works. Transfer-speeds were fine, close to 100MB/s with an external USB3 disk. It works nicely with Linux – plug and play.

Renesas-USB3-card_dead

Then the problems started…

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It looks nice on graphs, but there’s so much to not understand

sampling_theorem_hold_a

sampling_theorem_hold_b

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“Easy” remote-admin — static systemd service

In the previous two posts we dealt with the script ‘after.local’, which is a remnant on openSUSE of the ‘init’-days, before systemd became the standard.

After looking more closely, it turns out that there is a ‘unit-file’ for ‘after.local’ backward-compatibility. This makes the following rather simple.

Essentially we’ll just have to copy/rename/paste a few files to create a new service that does what we want ;-)

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“Easy” remote-admin — take 2

In my previous post I described a method for a boot-activated remote-admin option for my parents’ computer.

On 2nd thought, it is not always a good idea to rely on changing system-wide configurations (such as sshd_config, firewall…)

In this post I’ll basically re-do the whole thing. This time an extra SSH-server is started, in addition to any existing ones, listening on a custom port + custom config options. The firewall is dealt with in the script as well.

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“Easy” & quite safe remote-admin for parent’s linux machine

Yes, I know about KDE desktop sharing, FreeNX and relatives… and again yes, this is nothing new, but someone might still find it useful.

I wanted and needed something simple, something that could be activated in the bootloader menu (grub 2), something that didn’t leave the machine wide-open when absolutely not needed, something that would be robust and wasn’t necessarily depending on a working GUI.

1) KERNEL BOOT PARAMETERS

The boot-parameters that were used for the currently running kernel can be found in the file ‘/proc/cmdline’, easy to read and evaluate.

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