DTrace disk latency

[jpaetzel]

I've been playing around with DTrace. It's kind of interesting and I think some good things will come from it.

Code:

# kldload dtraceall
# dtrace -s /tmp/disklatencycmd.txt

The resolution of the attached script is good for spinning rust, not so much for SSDs, but it can be useful for pinpointing a bad drive.

 

[jpaetzel]

There's a number of other tools already on the system that use DTrace. They just aren't hooked up to the GUI.

For instance you can use zilstat -p <poolname> to examine the ZIL performance on a pool.

Or you can run dtruss -p pid to use DTrace to track a process.

 

[bestboy]

nice.
here's the output of my 2x2 mirror pool while reading:

Code:

<WDC WD30EFRX-68EUZN0 80.00A80>    at scbus0 target 0 lun 0 (ada0,pass0)
<WDC WD30EFRX-68EUZN0 80.00A80>    at scbus1 target 0 lun 0 (ada1,pass1)
<SAMSUNG HD204UI 1AQ10001>         at scbus2 target 0 lun 0 (ada2,pass2)
<SAMSUNG HD204UI 1AQ10001>         at scbus3 target 0 lun 0 (ada3,pass3)

Code:

maxada (0), us: 128702
maxada (1), us: 133637
maxada (2), us: 118185
maxada (3), us: 134905
 
avgada (0), us: 7229
avgada (1), us: 7072
avgada (2), us: 7374
avgada (3), us: 8144
 
stddevada (0), us: 9801
stddevada (1), us: 9578
stddevada (2), us: 7576
stddevada (3), us: 8076