From a4cb456631f0e70685fbc361eced9baa477a8c56 Mon Sep 17 00:00:00 2001
From: Michael Kerrin <michael.kerrin@hp.com>
Date: Tue, 16 Apr 2013 09:43:28 +0000
Subject: Volume IO usage gets reset to 0 after a reboot / crash

Check for reset of block device stats before updating volume usage cache.

If an instance is reboot or crashes, the results of block device stats for
that domain get reset. Add check that if block device stats are lower than
the current stats in the database, then add current values to totals and
update.

Change-Id: I3011872f8d80a1519771f8423001650dcbcc7f5b
Fixes bug: 1169097
---
 nova/virt/libvirt/driver.py | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

(limited to 'nova/virt')

diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index dc0af8539..d4daf5942 100755
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -2731,20 +2731,28 @@ class LibvirtDriver(driver.ComputeDriver):
                 mountpoint = bdm['device_name']
                 if mountpoint.startswith('/dev/'):
                     mountpoint = mountpoint[5:]
+                volume_id = bdm['volume_id']
 
                 LOG.debug(_("Trying to get stats for the volume %s"),
-                            bdm['volume_id'])
+                            volume_id)
                 vol_stats = self.block_stats(instance['name'], mountpoint)
 
                 if vol_stats:
-                    rd_req, rd_bytes, wr_req, wr_bytes, flush_ops = vol_stats
-                    vol_usage.append(dict(volume=bdm['volume_id'],
-                                          instance=instance,
-                                          rd_req=rd_req,
-                                          rd_bytes=rd_bytes,
-                                          wr_req=wr_req,
-                                          wr_bytes=wr_bytes,
-                                          flush_operations=flush_ops))
+                    stats = dict(volume=volume_id,
+                                 instance=instance,
+                                 rd_req=vol_stats[0],
+                                 rd_bytes=vol_stats[1],
+                                 wr_req=vol_stats[2],
+                                 wr_bytes=vol_stats[3],
+                                 flush_operations=vol_stats[4])
+                    LOG.debug(
+                        _("Got volume usage stats for the volume=%(volume)s,"
+                          " instance=%(instance)s, rd_req=%(rd_req)d,"
+                          " rd_bytes=%(rd_bytes)d, wr_req=%(wr_req)d,"
+                          " wr_bytes=%(wr_bytes)d")
+                        % stats)
+                    vol_usage.append(stats)
+
         return vol_usage
 
     def block_stats(self, instance_name, disk):
@@ -2757,7 +2765,8 @@ class LibvirtDriver(driver.ComputeDriver):
         except libvirt.libvirtError as e:
             errcode = e.get_error_code()
             LOG.info(_("Getting block stats failed, device might have "
-                       "been detached. Code=%(errcode)s Error=%(e)s")
+                       "been detached. Instance=%(instance_name)s "
+                       "Disk=%(disk)s Code=%(errcode)s Error=%(e)s")
                        % locals())
         except exception.InstanceNotFound:
             LOG.info(_("Could not find domain in libvirt for instance %s. "
-- 
cgit