# gmirror status
     Name    Status  Components
mirror/m1  DEGRADED  ada0 (SYNCHRONIZING, 25%)
                     ada1 (ACTIVE)
mirror/m2  COMPLETE  ada2 (ACTIVE)
                     ada4 (ACTIVE)
mirror/m3  COMPLETE  ada3 (ACTIVE)
                     ada5 (ACTIVE)
mirror/m4  DEGRADED  ada6 (SYNCHRONIZING, 1%)
                     ada7 (ACTIVE)
# newfs -O2 -U -b 65536 -f 8192 -t -E /dev/mirror/m4
/dev/mirror/m4: 953869.7MB (1953525152 sectors) block size 65536, fragment size 8192
        using 380 cylinder groups of 2512.19MB, 40195 blks, 161024 inodes.
        with soft updates
Erasing sectors [128...1953525151]
(ada6:ata3:0:0:0): DSM TRIM. ACB: 06 01 00 00 00 40 00 00 00 00 01 00
(ada6:ata3:0:0:0): CAM status: Command timeout
(ada6:ata3:0:0:0): Retrying command
(ada7:ata4:0:0:0): DSM TRIM. ACB: 06 01 00 00 00 40 00 00 00 00 01 00
(ada7:ata4:0:0:0): CAM status: Command timeout
(ada7:ata4:0:0:0): Retrying command
ada6 at ata3 bus 0 scbus9 target 0 lun 0
ada6: <Samsung SSD 850 EVO 1TB EMT02B6Q> s/n S2RFNX0HA17858N detached
GEOM_MIRRORada7 at ata4 bus 0 scbus10 target 0 lun 0
: ada7: Synchronization request failed (error=6).<Samsung SSD 850 EVO 1TB EMT02B6Q>  s/n S2RFNX0HA17713Aada6[WRITE(offset=18519556096, length=131072)] detached

GEOM_MIRROR: Device m4: provider ada6 disconnected.
GEOM_MIRROR: Device m4: rebuilding provider ada6 stopped.
GEOM_MIRROR: Cannot write metadata on ada7 (device=m4, error=6).
GEOM_MIRROR: Cannot update metadata on disk ada7 (error=6).
GEOM_MIRROR: Device m4: provider ada7 disconnected.
panic: _mtx_lock_sleep: recursed on non-recursive mutex gmirror:queue @ /freebsd/head/sys/modules/geom/geom_mirror/../../../geom/mirror/g_mirror.c:1017

cpuid = 2
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0469b9f820
vpanic() at vpanic+0x182/frame 0xfffffe0469b9f8a0
kassert_panic() at kassert_panic+0x126/frame 0xfffffe0469b9f910
__mtx_lock_sleep() at __mtx_lock_sleep+0x281/frame 0xfffffe0469b9f980
__mtx_lock_flags() at __mtx_lock_flags+0xfd/frame 0xfffffe0469b9f9d0
g_mirror_sync_done() at g_mirror_sync_done+0xb7/frame 0xfffffe0469b9fa00
g_io_deliver() at g_io_deliver+0x263/frame 0xfffffe0469b9fa80
g_mirror_destroy_provider() at g_mirror_destroy_provider+0xad/frame 0xfffffe0469b9fab0
g_mirror_update_device() at g_mirror_update_device+0x437/frame 0xfffffe0469b9faf0
g_mirror_worker() at g_mirror_worker+0x1f46/frame 0xfffffe0469b9fbb0
fork_exit() at fork_exit+0x84/frame 0xfffffe0469b9fbf0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe0469b9fbf0
--- trap 0, rip = 0, rsp = 0, rbp = 0 ---
KDB: enter: panic
[ thread pid 26 tid 100093 ]
Stopped at      kdb_enter+0x3b: movq    $0,kdb_why
db>