Change in vdsm[ovirt-3.4]: multiapth: Disable hba rescanning by default

Wednesday, 15 October 2014

Nir Soffer has uploaded a new change for review.

Change subject: multiapth: Disable hba rescanning by default
......................................................................

multiapth: Disable hba rescanning by default

Since commit 85d46e4572 we are scanning both iscsi bus and hbas when
issuing multipath.rescan(). We did not find any bad effects when testing
in our QE lab, but we have reports from customers that these rescans have
bad effects on FC connections.

This patch disables hba rescanning by default, so users can use this
feature if works for them, until we investigate this issue and provide
better solution.

This should have been part of the original patch, since we cannot test
all kinds of storage servers in the same setup and load used by all
users. If hba rescanning cannot be used with certain storage server, it
should be possible to disable this feature.

Change-Id: I812308e54ec2a9eab1ca4115e0456b2dd3990cfb
Bug-Url: https://bugzilla.redhat.com/1152587
Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt;
---
M lib/vdsm/config.py.in
M vdsm/storage/multipath.py
2 files changed, 9 insertions(+), 1 deletion(-)


  git pull ssh://gerrit.ovirt.org:29418/vdsm refs/changes/96/34196/1

diff --git a/lib/vdsm/config.py.in b/lib/vdsm/config.py.in
index 01fcc12..b7963b7 100644
--- a/lib/vdsm/config.py.in
+++ b/lib/vdsm/config.py.in
@@ -246,6 +246,11 @@
         ('vol_size_sample_interval', '60',
             'How often should the volume size be checked (seconds).'),
 
+        ('hba_rescan', 'false',
+            'Enable hba scanning when rescanning multipath. Required to '
+            'detect new or removed luns on FCP server. Disabled by default '
+            'since it may be disruptive.'),
+
         ('scsi_rescan_minimal_timeout', '2',
             'The minimum number of seconds to wait for scsi scan to return.'),
 
diff --git a/vdsm/storage/multipath.py b/vdsm/storage/multipath.py
index bbf2fc8..3531850 100644
--- a/vdsm/storage/multipath.py
+++ b/vdsm/storage/multipath.py
@@ -32,6 +32,7 @@
 
 from vdsm import constants
 from vdsm import utils
+from vdsm.config import config
 import misc
 import iscsi
 import supervdsm
@@ -104,7 +105,9 @@
 
     # First rescan iSCSI and FCP connections
     iscsi.rescan()
-    supervdsm.getProxy().hbaRescan()
+
+    if config.getboolean('irs', 'hba_rescan'):
+        supervdsm.getProxy().hbaRescan()
 
     # Now let multipath daemon pick up new devices
     misc.execCmd([constants.EXT_MULTIPATH], sudo=True)


-- 
To view, visit http://gerrit.ovirt.org/34196
To unsubscribe, visit http://gerrit.ovirt.org/settings

Gerrit-MessageType: newchange
Gerrit-Change-Id: I812308e54ec2a9eab1ca4115e0456b2dd3990cfb
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: ovirt-3.4
Gerrit-Owner: Nir Soffer <nsoffer(a)redhat.com&gt;

    

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