sg_get_disk_io_stats(3) 				     Library Functions Manual					   sg_get_disk_io_stats(3)

NAME

       sg_get_disk_io_stats, sg_get_disk_io_stats_diff - get disk io statistics

SYNOPSIS

       #include <statgrab.h>

       sg_disk_io_stats *sg_get_disk_io_stats(int *entries);

       sg_disk_io_stats *sg_get_disk_io_stats_diff(int *entries);

DESCRIPTION

       Both  calls  take  a  pointer to an int, entries, which is filled with the number of disks the machine has. This is needed to know how many
       sg_disk_io_stats structures have been returned. A pointer is returned to the first sg_disk_io_stats.

       sg_get_disk_io_stats returns the disk IO stored in the kernel which holds the amount of data transferred since bootup. On  some	platforms,
       such  as  Solaris 7, this value is stored in a 32bit int, so wraps around when it reaches 4GB. Other platforms, such as Solaris 8, hold the
       value in a 64bit int, which wraps somewhere near 17 million terabytes.

       sg_get_disk_io_stats_diff is the same as sg_get_disk_io_stats except it will return the difference since the last call. So, for instance  a
       call  to  sg_get_disk_io_stats_diff is made, and called again 5 seconds later. Over that time, 2000 bytes of traffic were written and 10000
       bytes read. write_bytes will store 2000 bytes, read_bytes will store 10000, and systime will  store  5.	 This  function  copes	with  wrap
       arounds by the O/S so should be seemless to use.

       On  Solaris  libstatgrab will attempt to get the cXtXdXsX representation for the disk_name string. If it fails it will use a name like sd0.
       On some systems programs calling libstatgrab will need elevated privileges to lookup some of the names. The  mappings  are  built  up  when
       sg_init is called.

RETURN VALUES

       All diskio statistics return a pointer to a structure of type sg_disk_io_stats.

       typedef struct{
	       char *disk_name;
	       long long read_bytes;
	       long long write_bytes;
	       time_t systime;
       }sg_disk_io_stats;

       disk_name
	      The name known to the operating system.  (eg. on linux it might be hda)

       read_bytes
	      The number of bytes the disk has read.

       write_bytes
	      The number of bytes the disk has written.

       systime
	      The time period over which read_bytes and write_bytes were transferred.

BUGS

       On  the very first call sg_get_disk_io_stats_diff will return the same as sg_get_disk_io_stats.	After the first call it will always return
       the difference.

       On operating systems that hold only 32bits of data there is a problem if the values wrap twice. For example, on Solaris 7 if 9GB is  trans-
       ferred and the operating system wraps at 4GB, the sg_get_disk_io_stats_diff function will return 5GB.

SEE ALSO

       statgrab(3)

WEBSITE

       http://www.i-scream.org/libstatgrab/

i-scream						   $Date: 2005/04/25 11:25:45 $ 				   sg_get_disk_io_stats(3)