Hi Rao,
The failover(fast) and giveback(slow) are vary from 4 seconds to 120 seconds, depends on Platform model, OnTap Version, Number of Volumes, I/O load. We need to tune two parameters(O2CB_HEARTBEAT_THRESHOLD and O2CB_IDLE_TIMEOUT_MS) to keep the VMs survive during CF failover, which are resides in /etc/sysconfig/o2cb file. By default the O2CB_HEARTBEAT_THRESHOLD 31 seconds and O2CB_IDLE_TIMEOUT_MS is 60000 milliseconds in OVM 3.1.1.
The netapp recommendation is 160 seconds to 190 sec based on considering storage controller and operating system timeout.
O2CB_HEARTBEAT_THRESHOLD = (((timeout in seconds) / 2) + 1) = (190/2)+1 = 91
Sl no. | Parameter | Min Value | Max value |
- 1.
| O2CB_HEARTBEAT_THRESHOLD | 81 | 91 |
- 2.
| O2CB_IDLE_TIMEOUT_MS | 160000 | 190000 |
In http://media.netapp.com/documents/tr-3712.pdf ovm best practice guide – Page 41 has the details about the above parameters for OVM 2.x but it’s applicable for OVM 3.x.
At the same time, tune the LUNs provided to VMs like the below to change it for 190 sec
for i in /sys/class/scsi_generic/*/device/timeout
do
echo 190 > "$i";
done
Regards,
karthikeyan.N
