=== A: pristine baseline (stock kernel, DragonFly 6.5-DEVELOPMENT #0 Jul 2)
(unit vn7)
=== a: /root/df2655/h2z.pristine.img mounted (uname: DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC )
--- read zfile (dd full 128KB):
1+1 records in
1+1 records out
114688 bytes transferred in 0.000709 secs (161691809 bytes/sec)
dd exit: 0
--- md5 read-back vs original:
MD5 (/root/df2655/zfile.A.readout) = 876569bdd45df2756a69a3fe85660f2a
MD5 (/root/df2655/zfile.orig) = 876569bdd45df2756a69a3fe85660f2a
--- first 32 bytes read back:
           44  46  32  36  35  35  2d  53  55  42  53  54  49  54  55  54
           49  4f  4e  2d  30  30  30  30  30  30  30  0a  44  46  32  36
--- first differing byte (orig vs readback):
--- zero-run length at start (bytes):
   65536
--- dmesg tail:
vn7: MBR magic not found; assume a COMPATIBILITY_SLICE (s0)
hammer2_mount: devstr="/dev/vn7@LOCAL"
hammer2_mount: device="/dev/vn7" label="LOCAL" rdonly=1
hammer2_ondisk: "/dev/vn7" zone=0 id=0 offset=0x0000000000000000 size=0x0000000080000000
hammer2_mount: hmp=0xfffff801252c0000 pmp=0xfffff801245e4000
HAMMER2: VOLDATA DUMP
HAMMER2: INITIATE SPANs
HAMMER2: CONN WAS TERMINATED