I use following dtrace script to trace the postion of one file on zfs:
#!/usr/sbin/dtrace -qs
zio_done:entry
/((zio_t *)(arg0))->io_vd/
{
zio=(zio_t *)arg0;
printf("Offset:%x and Size:%x\n",zio->io_offset,zio->io_size);
printf("vd:%x\n",(unsigned long)(zio->io_vd));
printf("process name:%s\n",execname);
tracemem(zio->io_data,40);
stack();
}
and I run dd command: "dd if=/export/dsk1/test1 bs=512 count=1", the dtrace
script will generate following it output:
Offset:657800 and Size:200
vd:ffffff02d6a1a700
process name:sched
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
zfs`zio_execute+0xa0
genunix`taskq_thread+0x193
unix`thread_start+0x8
^C
The tracemem output is the right context of file test1, which is a 512-byte
text file. "zpool status" has following output:
pool: tpool
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
tpool ONLINE 0 0 0
c2t0d0 ONLINE 0 0 0
errors: No known data errors
My question is how to translate zio->io_offset (0x657800, equal to decimal
number 6649856) outputed by dtace to block number on disk c2t0d0?
I tried to use "dd if=/dev/dsk/c2t0d0 of=text iseek=6650112 bs=512 count=1"
for a check,but the result is not right.
Thanks
Zhihui
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