Date: Sat, 20 Feb 2010 14:26:15 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Boris Samorodov <bsam@ipt.ru> Cc: freebsd-questions@freebsd.org Subject: Re: strange disk activity Message-ID: <20100220202614.GG70798@dan.emsphone.com> In-Reply-To: <97752307@ipt.ru> References: <97752307@ipt.ru>
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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.
--
Dan Nelson
dnelson@allantgroup.com
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