strange disk activity

[Boris Samorodov]

On Sat, 20 Feb 2010 14:26:15 -0600 Dan Nelson wrote:
> In the last episode (Feb 20), Boris Samorodov said:
> > Hello List,
> > 
> > I've got a very strange disk activity:
> > -----
> > % iostat -xw60 da0
> >                         extended device statistics  
> > device     r/s   w/s    kr/s    kw/s wait svc_t  b  
> > da0       43.2 204.4   971.9 10917.2    0  30.7  30 
> >                         extended device statistics  
> > device     r/s   w/s    kr/s    kw/s wait svc_t  b  
> > da0        5.1 274.6    72.7 15206.2    0  50.4  27 
> > 
> > If I'm not mistaken it's approx. 15Mb/sec. Which means more than 1000 Tb a
> > day!
> > 
> > How can I find which program is trashing the disk? The system is
> > FreeBSD-7.0 with 15 jails. Thanks for your help.

> Something like this would be a good start:

>  dtrace -n 'syscall::write:entry { @dist[pid,execname] = sum(arg2); }'

> Let it run a few seconds, then hit ^C, and it will print the total bytes
> written by each process during that period.  You may also have to trace
> writev and pwrite, since FreeBSD's dtrace doesn't include the sysinfo
> provider that would let you count them all at once.  

> Data written to swap or mmap'ped files won't register here, but most heavy
> writes aren't done with mmap.

Thanks, Dan! Dtrace is really a way to go.

Unfortunately dtrace is not available at 7.0. That means that
the system should be updated to 7-STABLE.

Are there other possibilities meanwhile?

-- 
WBR, Boris Samorodov (bsam)
Research Engineer, http://www.ipt.ru Telephone & Internet SP
FreeBSD Committer, http://www.FreeBSD.org The Power To Serve