Because I keep forgetting how I do it, here's how to enable filesystem quotas on a reasonably recent Debian server. For simplicity, let's say the mountpoint is /home and the device /dev/storage/home.

sudo apt install quota

• Add usrquota as a mount option to the /etc/fstab for /home

sudo systemctl daemon-reload
sudo umount /home
sudo tune2fs -O quota /dev/storage/home
sudo mount /home

For usrquota alone, a remount should be sufficient, but tune2fs needs to run offline in this case. Now, all that's left is setting quotas. This only needs to be run once for each new account, preferable automatically as part of some kind of account management system.

setquota -u account block-soft block-hard inode-soft inode-hard /home

You can check quota settings and usage with repquota -as.

When setting up my new work laptop (replacing the more than eight years old X270 that I used before), I found that the freshly installed Debian unstable was unable to produce any kind of graphics output. X11 complained about not finding any screens, and the text console also broke as soon as the kernel tried configuring it. Long story short: Turns out that Linux 6.12, as shipped with Debian unstable, is simply too old for Intel Arc 130V/140V graphics and/or Intel Lunar Lake / Core 258V CPUs. With Linux 6.14, everything works right out of the box.

Luckily, you can just install Ubuntu kernels on Debian. So, solving this issue was as simple as issuing the following commands:

wget \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-headers-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-headers-6.14.0-061400_6.14.0-061400.202503241442_all.deb \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-image-unsigned-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-modules-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb
sudo apt install \
  ./linux-headers-6.14.0-061400_6.14.0-061400.202503241442_all.deb \
  ./linux-headers-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  ./linux-modules-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  ./linux-image-unsigned-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb

The new kernel version is automatically picked up by GRUB, so one reboot later everything worked as intended.

In late May 2025, dm2lct and I hiked across the Jizera mountains (CZ: Góry Izerskie / PL: Jizerské hory / DE: Isergebirge), right at the Czech – Polish border. It's a very nice hike with some stunning views, and doable as a single-day trip from and back to Dresden – even with rail replacement services here and there. Just note that you might want to wear water-tight boots – at least when we were up there, the majority of hiking trails on the summit were actually water streams.

Arrival

We decided to start our climb from Świeradów-Zdrój (DE: Bad Flinsberg on the Polish side of the mountains. We did have to get up at a slightly ungodly hour, but that was definitely worth it.

• TL RB60 Dresden Hbf (06:53) → Görlitz Hbf (08:33) – Deutschlandticket

As the direct connection to Zgorzelec was closed, apparently due to issues related to the German/Polish language level of the train drivers, the route to Świeradów-Zdrój included a nice little 50-minute detour through the twin towns of Görlitz and Zgorzelec. I think I'll come back for a proper visit to Görlitz old town on a later day. It even has a small tram network! Zgorzelec train station is quite cozy as well, featuring a small café right next to the waiting room.

• KD 69874 Zgorzelec (09:44) → Świeradów-Zdrój (10:55) – 18.75 PLN (4.45 €) each

The tracks in Poland had very noticeable rail joints – and a tight curve in Lubań actually mannaged to topple our water bottle. Apart from that, it's a pretty standard Diesel train connection, ending at the single-platform terminus in Świeradów-Zdrój.

Going Up

Świeradów-Zdrój sits about 500 metres above sea level; the Jizera and Smrk peaks clock in at 1,107 and 1,124 metres, respectively. There's a cabin lift to Stóg Izerskie (DE: Heufuder) situated about a kilometre from the train station, seemingly operating year-round, but walking certainly is the more interesting option.

After a few hundred metres through the town itself, you're faced with two options: a (partially serpentine) road, or a more direct (and, thus, steep) gravel-rock-ish path. We chose the latter option, which seems to be marked with a red-on-white stripe.

The path was mostly dry, except for a short segment near the Świeradówka reservoir that basically consisted of walking through a sometimes stony and sometimes just outright muddy water stream. That segment is not mandatory: an asphalt road offers the same way up with a slight (but dry) detour.

Apart from that, the way up already offers some very nice views into the valley – you just need to turn around and look back every now and then. The views include a wooden obseravtion tower sitting almost in the valley itself. I have no idea why it's there.

Lunch Break

Once atop Stóg Izerskie (DE: Heufuder, you can stop for lunch at Schronisko na Stogu Izerskim (DE: Heufuderbaude), a hostel/restaurant thingy offering typical Polish food such as Pierogi (a kind of dumplings). Otherwise, you can still go there and enjoy the views from the terrace.

Across the Ridge

Our next stop was Smrk (PL: Smrek / DE: Tafelfichte). It's three metres lower than the highest peak of the Jizera Mountains (namely, Wysoka Kopa / DE: Hinterberg), but features a nice observation deck.

The way to Smrk is comparatively even, but full of water streams that double as trails. It's pretty; just try not to get wet feet. It also features a border crossing from Poland to the Czech republic. In our case, the “welcome to Poland” sign on the way back was missing, but the border stone itself was still present.

View

It's pretty cold and drafty on the observation tower, but the views are absolutely worth it.

Going Down

While our original plan was to return to Świeradów-Zdrój, we spontaneously decided that Nové Město pod Smrkem on the Czech side should give for a more interesting trip. It was a bit of a close call – the last train to Liberec departed around 17:00, and there was just a single fallback connection near 19:00 that might still have taken us home in case we missed the one to Liberec. Note that this was regular weekday service.

From the observation tower, you can follow paths marked with a blue-on-white stripe for a reasonably direct, steep, and as often as not watery path down. The views alongside it do not disappoint at all, and even down in the valley there's still quite an angle to the nature around you.

Departure

We arrived in Nové Město pod Smrkem at 16:45, 15 minutes before the last train to Liberec departed. Normally, there is a connection from Liberec to Zittau (DE) that would've taken us directly back to Dresden, but as there was only rail replacement bus service available we went with the slightly longer, but at least equally scenic route via Děčín – featuring a nice view towards Ještěd (DE: Jeschken) and its iconic tower. Even on the train, you really notice that the Czech Republic is in more of a mountainside than conventional countryside situation. Also, the ARV train used OpenStreetMap on its passenger information display, which is cool.

• Os 6381 Nové Město pod Smrkem (17:01) → Liberec (17:57) – 70 CZK (2.83 €) each
• ARV 1334 Liberec (18:28) → Děčín hl.n. (20:10) – 196 CZK (7.92 €) each
• RB U28 Děčín hl.n. (20:41) → Bad Schandau (21:09) – 1.80 € or so each
• S1 Bad Schandau (21:44) → Dresden Hbf (22:28) – Deutschlandticket

All pictures from the trip are available on lib.finalrewind.org/Góry Izerskie 2025.

Occasionally, I need to open remote LUKS2 images (i.e., files) that I access via SSHFS. This used to work just fine: mount an sshfs, run cryptsetup luksOpen and access the underlying filesystem. However, a recent cryptsetup upgrade introduced (or changed?) its locking mechanism. Now, before opening an image file, it tries to aqcuire a read lock, which will fail with ENOSYS (Function not implemented) on sshfs mountpoints. This, in turn, causes cryptsetup to report "Failed to acquire read lock on device" and "Device ... is not a valid LUKS device.".

There doesn't seem to be a simple way of disabling this (admittedly, in 99% of cases desirable) feature, so for now I'm working around it by just having flock always return success, thanks to the magic of LD_PRELOAD and a flock stub:

#include <sys/file.h>

int flock(int fd, int operation)
{
    return 0;
}

Compile as follows:

> ${CC} -O2 -Wall -fPIC -c -o ignoreflock.o ignoreflock.c
> ${CC} -fPIC -O2 -Wall -shared -Wl,-soname,ignoreflock.so.0 -o ignoreflock.so.0 ignoreflock.o -ldl

And then call LD_PRELOAD=..../ignoreflock.so.0 cryptsetup luksOpen ... (or sudo env LD_PRELOAD=..../ignoreflock.so.0 cryptsetup luksOpen ...). ignoreflock provides a handy stub, Makefile and wrapper script for this.