g_vfs_done() error = 6

[Mario Pavlov]

Hi list,
I was running my FreeBSD-amd64 7 stable for quite some time without any problems until suddenly it started to spit out those:

ad10: detached
g_vfs_done(): ad10s2a[READ(offset=412188672, length=16384)]error = 6
g_vfs_done(): ad10s2a[READ(offset=412188672, length=16384)]error = 6
vm_fault: pager read error, pid 698 (devd)
g_vfs_done(): ad10s2a[READ(offset=98304, length=16384)]error = 6
g_vfs_done(): ad10s2a[READ(offset=578027520, length=16384)]error = 6
g_vfs_done(): ad10s2a[READ(offset=1348599808, length=16384)]error = 6
...
...
...
panic: vinvalbuf: dirty bufs
cpuid = 0
KDB: enter: panic
[thread pid 960 tid 100057]
Stopped at kdb_enter+0x3d: movq $0,0x431b24(%rip)

then I'm in the db> "prompt"
and after a few minutes I get this:

panic: knlist not locked, but should be
cpuid = 0
Cannot dump, no dump device defined
Automatic reboot in 15 seconds...

what I want to find out is whether this is caused by hardware failure or it's software problem
I upgraded to 8-CURRENT just to try if it will be the same and it is

do you think this is hardware problem or not ?
thank you

Regards
MGP