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* collectd - src/md.c
* Copyright (C) 2010,2011 Michael Hanselmann
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; only version 2 of the License is applicable.
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* General Public License for more details.
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
* Author:
* Michael Hanselmann
#include "collectd.h"
#include "common.h"
#include "plugin.h"
#include "utils_ignorelist.h"
#include <sys/ioctl.h>
#include <linux/major.h>
#include <linux/raid/md_u.h>
#define PROC_DISKSTATS "/proc/diskstats"
#define DEV_DIR "/dev"
static const char *config_keys[] =
static int config_keys_num = STATIC_ARRAY_SIZE (config_keys);
static ignorelist_t *ignorelist = NULL;
static int md_config (const char *key, const char *value)
if (ignorelist == NULL)
ignorelist = ignorelist_create (/* invert = */ 1);
if (ignorelist == NULL)
return (1);
if (strcasecmp (key, "Device") == 0)
ignorelist_add (ignorelist, value);
else if (strcasecmp (key, "IgnoreSelected") == 0)
ignorelist_set_invert (ignorelist, IS_TRUE (value) ? 0 : 1);
return (-1);
return (0);
static void md_submit (const int minor, const char *type_instance,
gauge_t value)
value_t values[1];
value_list_t vl = VALUE_LIST_INIT;
values[0].gauge = value;
vl.values = values;
vl.values_len = 1;
sstrncpy (, hostname_g, sizeof (;
sstrncpy (vl.plugin, "md", sizeof (vl.plugin));
ssnprintf (vl.plugin_instance, sizeof (vl.plugin_instance),
"%i", minor);
sstrncpy (vl.type, "md_disks", sizeof (vl.type));
sstrncpy (vl.type_instance, type_instance,
sizeof (vl.type_instance));
plugin_dispatch_values (&vl);
} /* void md_submit */
static void md_process (const int minor, const char *path)
char errbuf[1024];
int fd;
struct stat st;
mdu_array_info_t array;
gauge_t disks_missing;
fd = open (path, O_RDONLY);
if (fd < 0)
WARNING ("md: open(%s): %s", path,
sstrerror (errno, errbuf, sizeof (errbuf)));
if (fstat (fd, &st) < 0)
WARNING ("md: Unable to fstat file descriptor for %s: %s", path,
sstrerror (errno, errbuf, sizeof (errbuf)));
close (fd);
if (! S_ISBLK (st.st_mode))
WARNING ("md: %s is no block device", path);
close (fd);
if (st.st_rdev != makedev (MD_MAJOR, minor))
WARNING ("md: Major/minor of %s are %i:%i, should be %i:%i",
path, (int)major(st.st_rdev), (int)minor(st.st_rdev),
(int)MD_MAJOR, minor);
close (fd);
/* Retrieve md information */
if (ioctl (fd, GET_ARRAY_INFO, &array) < 0) {
WARNING ("md: Unable to retrieve array info from %s: %s", path,
sstrerror (errno, errbuf, sizeof (errbuf)));
close (fd);
close (fd);
* The mdu_array_info_t structure contains numbers of disks in the array.
* However, disks are accounted for more than once:
* active: Number of active (in sync) disks.
* spare: Number of stand-by disks.
* working: Number of working disks. (active + sync)
* failed: Number of failed disks.
* nr: Number of physically present disks. (working + failed)
* raid: Number of disks in the RAID. This may be larger than "nr" if
* disks are missing and smaller than "nr" when spare disks are
* around.
md_submit (minor, "active", (gauge_t) array.active_disks);
md_submit (minor, "failed", (gauge_t) array.failed_disks);
md_submit (minor, "spare", (gauge_t) array.spare_disks);
disks_missing = 0.0;
if (array.raid_disks > array.nr_disks)
disks_missing = (gauge_t) (array.raid_disks - array.nr_disks);
md_submit (minor, "missing", disks_missing);
} /* void md_process */
static int md_read (void)
FILE *fh;
char buffer[1024];
fh = fopen (PROC_DISKSTATS, "r");
if (fh == NULL) {
char errbuf[1024];
WARNING ("md: Unable to open %s: %s",
sstrerror (errno, errbuf, sizeof (errbuf)));
return (-1);
/* Iterate md devices */
while (fgets (buffer, sizeof (buffer), fh) != NULL)
char path[PATH_MAX];
char *fields[4];
char *name;
int major, minor;
/* Extract interesting fields */
if (strsplit (buffer, fields, STATIC_ARRAY_SIZE(fields)) < 3)
major = atoi (fields[0]);
if (major != MD_MAJOR)
minor = atoi (fields[1]);
name = fields[2];
if (ignorelist_match (ignorelist, name))
/* FIXME: Don't hardcode path. Walk /dev collecting major,
* minor and name, then use lookup table to find device.
* Alternatively create a temporary device file with correct
* major/minor, but that again can be tricky if the filesystem
* with the device file is mounted using the "nodev" option.
ssnprintf (path, sizeof (path), "%s/%s", DEV_DIR, name);
md_process (minor, path);
fclose (fh);
return (0);
} /* int md_read */
void module_register (void)
plugin_register_config ("md", md_config, config_keys, config_keys_num);
plugin_register_read ("md", md_read);
} /* void module_register */
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