Dell Unity: NFS clients stop responding or encounter performance issues when accessing the destination side of replication
Summary: Random stop responding conditions and performance issues while trying to access the exports on the destination side of replication. (User Correctable)
Symptoms
NFS exports created on the destination NAS server using a backup interface.
Random stop responding conditions and performance issues while trying to access the exports on the destination side of replication.
Network trace analysis shows that the NFS requests are reaching the NAS server, but the NAS server is not responding.
var/log/sm_daemon.log
2021-06-01 16:01:43.049778 [7f1f973ea700]TRACE sm_del_all_by_mark delete_objects(509): Deleting <NAddr>: IPv4 link=0x000c scope=0 label='bond3.218' addr='x.x.x.x/16' flags=Secondary+/Temporary+/NoDAD-/Optimistic-/DADFailed-/Homeaddress-/Deprecated-/Tentative-/Permanent+
2021-06-01 16:01:43.051418 [7f1f973ea700]TRACE sm_del_all_by_mark delete_objects(509): Deleting <NAddr>: IPv4 link=0x000e scope=0 label='bond3.661' addr='x.x.x.x/22' flags=Secondary+/Temporary+/NoDAD-/Optimistic-/DADFailed-/Homeaddress-/Deprecated-/Tentative-/Permanent+ <--- IP in question
2021-06-01 16:01:43.052528 [7f1f973ea700]TRACE sm_del_all_by_mark delete_objects(509): Deleting <NAddr>: IPv4 link=0x000f scope=0 label='bond3.671' addr='x.x.x.x/22' flags=Secondary+/Temporary+/NoDAD-/Optimistic-/DADFailed-/Homeaddress-/Deprecated-/Tentative-/Permanent+
2021-06-01 16:01:43.053629 [7f1f973ea700]TRACE sm_del_all_by_mark delete_objects(509): Deleting <NAddr>: IPv4 link=0x29ba scope=0 label='bond3.651' addr='x.x.x.x/22' flags=Secondary-/Temporary-/NoDAD-/Optimistic-/DADFailed-/Homeaddress-/Deprecated-/Tentative-/Permanent+ <--- IP that prompts bond removal
2021-06-01 16:01:43.055136 [7f1f973ea700]TRACE sm_del_all_by_mark delete_objects(509): Deleting <NLink>: type=4 link=0x29ba media=0x01 flags=Connected+/Up+/Promisc-/Master-/Slave- flags=0x00011043 flagsChange=0x00000000 MTU=1500 MAC='00:60:16:5c:56:04' name='bondx.xxx' parentLink=0x000a VLAN=xxx kind='vlan' PCIAddr='' NICName='' SpeedDuplex/AutoNeg=0/0,supported{}/0,partner{}/0,advertised{}/0 FlowControl/AutoNeg=0/0 NetNS=0 <--- bond removal
/var/log/messages
2021-06-01T16:01:53+00:00 self kernel: [15786728.512641] unregister_netdevice: waiting for bond3.651 to become free. Usage count = 2 2021-06-01T16:02:03+00:00 self kernel: [15786738.588540] unregister_netdevice: waiting for bond3.651 to become free. Usage count = 2 2021-06-01T16:02:13+00:00 self kernel: [15786748.700452] unregister_netdevice: waiting for bond3.651 to become free. Usage count = 2
This issue can occur under the following circumstances:
- The NAS server is the destination side of replication
- Packet reflect is enabled on the source side of replication
The destination NAS server can encounter problems when bringing up the IP reflect cache after coming out of a paused state.
During normal operations, the destination NAS server pauses then play delta information associated with replication.
The NAS server then unpause and bring the interfaces back online, and the associated IP reflect cache.
There is a chance that when the NAS server brings the interface back online it stops responding and fail to respond to NFS client requests.
This condition is intermittent. The NAS server can run for a set period of time then encounter the issue.
It is possible that the NAS server can experience the issue right away or run for a long period of time before the issue is triggered.
This issue can manifest itself in many different ways.
It can cause the SP to panic.
Creating or delete interfaces on the destination NAS server can fail and leave the NAS server in a degraded state.
Cause
This is a code issue with Unity code below 5.07.
Resolution
Workarounds
Disable or pause replication.
Disable IP reflect on the source side (it will be disabled on the destination side)
Upgrade to 5.07