This is an initial implementation of a plugin to collect information
about Linux Software-RAID (md) devices. It reports the number of
component devices, number of devices in array, number of active,
working, failed and spare disks.

Signed-off-by: Michael Hanselmann <[email protected]>
---

This is a patch I already sent once in early October 2010. Unfortunately it was
not applied at the time. The patch below is rebased on top of the master branch.

 configure.in          |   19 +++++
 src/Makefile.am       |    8 ++
 src/collectd.conf.in  |    6 ++
 src/collectd.conf.pod |   24 ++++++
 src/md.c              |  204 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/types.db          |    1 +
 6 files changed, 262 insertions(+), 0 deletions(-)
 create mode 100644 src/md.c

diff --git a/configure.in b/configure.in
index 8db24ca..d6e1ed7 100644
--- a/configure.in
+++ b/configure.in
@@ -298,6 +298,21 @@ fi
 # For hddtemp module
 AC_CHECK_HEADERS(linux/major.h libgen.h)
 
+# For md module (Linux only)
+if test "x$ac_system" = "xLinux"
+then
+       AC_CHECK_HEADERS(linux/raid/md_u.h,
+                        [have_linux_raid_md_u_h="yes"],
+                        [have_linux_raid_md_u_h="no"],
+[
+#include <sys/ioctl.h>
+#include <linux/major.h>
+#include <linux/types.h>
+])
+else
+       have_linux_raid_md_u_h="no"
+fi
+
 # For the battery plugin
 AC_CHECK_HEADERS(IOKit/ps/IOPowerSources.h, [], [],
 [
@@ -4334,6 +4349,7 @@ plugin_irq="no"
 plugin_libvirt="no"
 plugin_load="no"
 plugin_memory="no"
+plugin_md="no"
 plugin_multimeter="no"
 plugin_nfs="no"
 plugin_fscache="no"
@@ -4367,6 +4383,7 @@ then
        plugin_irq="yes"
        plugin_load="yes"
        plugin_memory="yes"
+       plugin_md="$have_linux_raid_md_u_h"
        plugin_nfs="yes"
        plugin_fscache="yes"
        plugin_processes="yes"
@@ -4653,6 +4670,7 @@ AC_PLUGIN([match_regex], [yes],                [The regex 
match])
 AC_PLUGIN([match_timediff], [yes],             [The timediff match])
 AC_PLUGIN([match_value], [yes],                [The value match])
 AC_PLUGIN([mbmon],       [yes],                [Query mbmond])
+AC_PLUGIN([md],          [$plugin_md],         [Query md devices])
 AC_PLUGIN([memcachec],   [$with_libmemcached], [memcachec statistics])
 AC_PLUGIN([memcached],   [yes],                [memcached statistics])
 AC_PLUGIN([memory],      [$plugin_memory],     [Memory usage])
@@ -4980,6 +4998,7 @@ Configuration:
     match_timediff  . . . $enable_match_timediff
     match_value . . . . . $enable_match_value
     mbmon . . . . . . . . $enable_mbmon
+    md  . . . . . . . . . $enable_md
     memcachec . . . . . . $enable_memcachec
     memcached . . . . . . $enable_memcached
     memory  . . . . . . . $enable_memory
diff --git a/src/Makefile.am b/src/Makefile.am
index 5728144..b9785fc 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -593,6 +593,14 @@ collectd_LDADD += "-dlopen" mbmon.la
 collectd_DEPENDENCIES += mbmon.la
 endif
 
+if BUILD_PLUGIN_MD
+pkglib_LTLIBRARIES += md.la
+md_la_SOURCES = md.c
+md_la_LDFLAGS = -module -avoid-version
+collectd_LDADD += "-dlopen" md.la
+collectd_DEPENDENCIES += md.la
+endif
+
 if BUILD_PLUGIN_MEMCACHEC
 pkglib_LTLIBRARIES += memcachec.la
 memcachec_la_SOURCES = memcachec.c
diff --git a/src/collectd.conf.in b/src/collectd.conf.in
index 94cf2a9..6b6c1c4 100644
--- a/src/collectd.conf.in
+++ b/src/collectd.conf.in
@@ -89,6 +89,7 @@
 #@BUILD_PLUGIN_LPAR_TRUE@LoadPlugin lpar
 #@BUILD_PLUGIN_MADWIFI_TRUE@LoadPlugin madwifi
 #@BUILD_PLUGIN_MBMON_TRUE@LoadPlugin mbmon
+#@BUILD_PLUGIN_MD_TRUE@LoadPlugin md
 #@BUILD_PLUGIN_MEMCACHEC_TRUE@LoadPlugin memcachec
 #@BUILD_PLUGIN_MEMCACHED_TRUE@LoadPlugin memcached
 @BUILD_PLUGIN_MEMORY_TRUE@@BUILD_PLUGIN_MEMORY_TRUE@LoadPlugin memory
@@ -428,6 +429,11 @@
 #      Port "411"
 #</Plugin>
 
+#<Plugin md>
+#      Device "/dev/md0"
+#      IgnoreSelected false
+#</Plugin>
+
 #<Plugin memcachec>
 #      <Page "plugin_instance">
 #              Server "localhost"
diff --git a/src/collectd.conf.pod b/src/collectd.conf.pod
index ed979c4..c63bfff 100644
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -1812,6 +1812,30 @@ TCP-Port to connect to. Defaults to B<411>.
 
 =back
 
+=head2 Plugin C<md>
+
+The C<md plugin> collection information from Linux Software-RAID devices (md).
+
+All reported values are of the type "md_disks". Reported type instances are
+"number" (number of component devices), "raid" (number of devices in the
+array), "active", "working", "failed" (number of failed disks) and "spare"
+(number of spare disks).
+
+=over 4
+
+=item B<Device> I<Device>
+
+Select md devices based on device name. See B<IgnoreSelected> for more details.
+
+=item B<IgnoreSelected> I<true>|I<false>
+
+Invert device selection: If set to true, all md devices B<except> those listed
+using B<Device> are collected. If false (the default), only those listed are
+collected. If no configuration is given, the B<md> plugin will collect data
+from all md devices.
+
+=back
+
 =head2 Plugin C<memcachec>
 
 The C<memcachec plugin> connects to a memcached server, queries one or more
diff --git a/src/md.c b/src/md.c
new file mode 100644
index 0000000..65cf3d4
--- /dev/null
+++ b/src/md.c
@@ -0,0 +1,204 @@
+/**
+ * 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
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * 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[] =
+{
+       "Device",
+       "IgnoreSelected",
+};
+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);
+       }
+       else
+       {
+               return (-1);
+       }
+
+       return (0);
+}
+
+static void md_submit (const int minor,
+                       const char *type, 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 (vl.host, hostname_g, sizeof (vl.host));
+       sstrncpy (vl.plugin, "md", sizeof (vl.plugin));
+       ssnprintf (vl.plugin_instance, sizeof (vl.plugin_instance),
+                  "%i", minor);
+       sstrncpy (vl.type, type, 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;
+
+       fd = open (path, O_RDONLY);
+       if (fd < 0)
+       {
+               WARNING ("md: open(%s): %s", path,
+                        sstrerror (errno, errbuf, sizeof (errbuf)));
+               return;
+       }
+
+       if (fstat (fd, &st) < 0)
+       {
+               WARNING ("md: Unable to fstat file descriptor for %s: %s", path,
+                        sstrerror (errno, errbuf, sizeof (errbuf)));
+               close (fd);
+               return;
+       }
+
+       if (! S_ISBLK (st.st_mode))
+       {
+               WARNING ("md: %s is no block device", path);
+               close (fd);
+               return;
+       }
+
+       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);
+               return;
+       }
+
+       /* 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);
+               return;
+       }
+
+       close (fd);
+
+       md_submit (minor, "md_disks", "number", array.nr_disks);
+       md_submit (minor, "md_disks", "raid", array.raid_disks);
+       md_submit (minor, "md_disks", "active", array.active_disks);
+       md_submit (minor, "md_disks", "working", array.working_disks);
+       md_submit (minor, "md_disks", "failed", array.failed_disks);
+       md_submit (minor, "md_disks", "spare", array.spare_disks);
+
+       return;
+} /* 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 " PROC_DISKSTATS ": %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)
+                       continue;
+
+               major = atoi (fields[0]);
+
+               if (major != MD_MAJOR)
+                       continue;
+
+               minor = atoi (fields[1]);
+               name = fields[2];
+
+               /* 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), DEV_DIR "/%s", name);
+
+               if (ignorelist_match (ignorelist, path))
+                       continue;
+
+               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 */
diff --git a/src/types.db b/src/types.db
index e6345ab..8557fe6 100644
--- a/src/types.db
+++ b/src/types.db
@@ -84,6 +84,7 @@ irq                   value:DERIVE:0:U
 latency                        value:GAUGE:0:65535
 links                  value:GAUGE:0:U
 load                   shortterm:GAUGE:0:100, midterm:GAUGE:0:100, 
longterm:GAUGE:0:100
+md_disks               value:GAUGE:0:U
 memcached_command      value:DERIVE:0:U
 memcached_connections  value:GAUGE:0:U
 memcached_items                value:GAUGE:0:U
-- 
1.7.1


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