#HAMMER2
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ijanc.org
Fixed a HAMMER2 deadlock on OpenBSD, taking a shared chain lock again would sleep if a writer was waiting, and the writer was waiting on us. Added RW_READAGAIN to rwlock(9) for that. It's the 0x202 in the last two rrw_enter calls. #OpenBSD
gdb disassembly of hammer2_chain_lock showing six rrw_enter calls; the last two pass 0x202 (RW_READ|RW_READAGAIN).
September 25, 2026 at 3:02 AM
ijanc.org
HAMMER2 running on OpenBSD: mount, PFS, snapshots, lz4 compression and fsck, WITNESS enabled. First came the import of the fs and its tools, now it's hunting lock order reversals. Still a TODO list, but it's usable. #OpenBSD
September 23, 2026 at 11:33 PM
teku-a-fool.bsky.social
YEAR OF BSD #os-tan
September 13, 2026 at 3:12 PM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3EBD4D
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-08-28 09:24:15 CEST
Min Alt: 13250 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
August 28, 2026 at 7:26 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3EBD4D
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-08-24 12:14:56 CEST
Min Alt: 5900 ft
Squawk: #0033
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
August 24, 2026 at 10:17 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3F4A57
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-08-13 15:56:49 CEST
Min Alt: 24000 ft
Squawk: #1347
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
August 13, 2026 at 1:57 PM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3F4A57

Flt: #HAMMER2 # #
Time: 2026-08-12 09:50:01 CEST
Min Alt: 15375 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
August 12, 2026 at 7:50 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3F4A57
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-08-11 09:34:45 CEST
Min Alt: 21575 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
August 11, 2026 at 7:36 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3EA03F
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-08-07 09:32:32 CEST
Min Alt: 11450 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
August 7, 2026 at 7:34 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3E9C83
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-07-23 09:04:05 CEST
Min Alt: 11075 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
July 23, 2026 at 7:06 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3F976B
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-07-22 09:29:56 CEST
Min Alt: 18275 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
July 22, 2026 at 7:32 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3E91CD
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-07-01 10:24:15 CEST
Min Alt: 19600 ft
Squawk: #0711
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
July 1, 2026 at 8:24 AM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3F78FB
Owner: #GERMANAIRFORCE
Flt: #HAMMER2 # #
Time: 2026-05-27 09:37:28 CEST
Min Alt: 10850 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
May 27, 2026 at 7:41 AM
ijanc.org
First mount/umount of #HAMMER2 on #OpenBSD

A series of screencasts of hammer2 commands in OpenBSD, exploring everyday situations. Today we'll cover mount and umount. Soon I will publish a video (~6 min) applying a kernel patch + userland to get to the point in this video.
May 5, 2026 at 4:33 PM
ijanc.org
Now we have a starting point #hammer2 #FFS #OpenBSD and FFS won the first match. Perhaps lists.dragonflybsd.org/pipermail/co... XOP (executable operation) github.com/kusumi/openb... doesn't appear to have
April 29, 2026 at 12:28 AM
ijanc.org
Checking #HAMMER2 on #OpenBSD

github.com/kusumi/openb...
April 28, 2026 at 12:13 AM
ijanc.org
Spent the evening chasing a #HAMMER2 bug on #OpenBSD every mtime stuck at "31-12-1969". Not epoch zero the on-disk field is µs since 1970, but the kernel wrote seconds microtime(9) gettime() rt a count of sec

*t = (uint64_t)ts.tv_sec * 1000000ULL + ts.tv_nsec / 1000;

github.com/kusumi/openb...
github.com
April 27, 2026 at 4:32 PM
aboveheerlen.bsky.social
#PlaneAlert ICAO: #3E9443
Owner: #THEFLYINGBULLS
Flt: #HAMMER2 #DHTDM #
Time: 2026-04-20 09:53:24 CEST
Min Alt: 18050 ft
Squawk: #0032
#aircraft over #heerlen - #adsb #planefence by kx1t - sdr-e airplanes flightaware
April 20, 2026 at 7:56 AM
atax1a.infosec.exchange.ap.brid.gy
tired: zfs vs btrfs on linux

inspired: zfs vs hammer2 on freebsd
March 14, 2026 at 7:29 PM
dendrobatus-azureus.bsd.cafe.ap.brid.gy
Quote from Hammer2 page

Because HAMMER2 is a block copy-on-write filesystem, the "atime" field is not supported and will typically just reflect local system in-memory caches or mtime.

The radix tree is dynamic in that each entry can dynamically control how many bits it chops off. This allows […]
Original post on mastodon.bsd.cafe
mastodon.bsd.cafe
February 5, 2026 at 11:35 AM
dendrobatus-azureus.bsd.cafe.ap.brid.gy
Additional Reference Material

HAMMER2 Design v6 (08-Dec-2018)

https://gitweb.dragonflybsd.org/dragonfly.git/blob/57614c517203403e7fe4a34c370c7151ba52c539:/sys/vfs/hammer2/DESIGN

#filesystem #programming #bsd #dragonflybsd #freebsd #opensource #technology #no #fsk
gitweb.dragonflybsd.org Git - dragonfly.git/blob - sys/vfs/hammer2/DESIGN
gitweb.dragonflybsd.org
February 5, 2026 at 11:22 AM
dendrobatus-azureus.bsd.cafe.ap.brid.gy
The amazing DragonFlyBSD has the fantastic
Hammer2 filesystem:

* Block copy-on-write filesystem
* Instant recovery on mount
* Instant snapshots
* Mounted snapshots are writable
* Automatic snapshotting can be enabled at the system level via periodic scripts
* Default Periodic also does daily […]
Original post on mastodon.bsd.cafe
mastodon.bsd.cafe
February 5, 2026 at 11:18 AM
dendrobatus-azureus.bsd.cafe.ap.brid.gy
Here you can read how ROBUST the HAMMER2 filesystem is

https://www.dragonflybsd.org/hammer/

#dragonfly #dragonflybsd #bsd #freebsd #opensource #lightweight #hammer2 #filesystem #technology #programming
November 24, 2025 at 9:37 PM
hyperreal.at.moonshadow.dev
DragonFly BSD In 2026: The Lightweight BSD That’s Still A Beast
Most people have never heard of it, but DragonFly BSD is quietly outpacing the competition where it matters most: multi-core performance, rock-solid HAMMER2 filesystem with snapshots & remote-mount, a...
techrefreshing.com
November 23, 2025 at 11:17 AM