# Controllers
Controller Objects in the VPSA represent the clustered virtual
controller pair of a VPSA.
## Failover
Failover halts the active controller and activates the standby
controller with minimal I/O interruption.
In the Controllers screen, click **Failover** to manually trigger failover.
## Restart File Services
Restart File Services terminates and reactivates SMB or NFS file service
processes on the selected controller.
The restart action is almost instantaneous.
Restarting file services is recommended in cases where a folder from the
SMB File History Snapshot has been left open on a client, preventing deletion
upon expiry, and generating a failure error.
In this case, restarting file services releases the client file handle,
allowing the deletion to proceed.
To restart file services:
1. In the navigation tree, select **Resources > Controllers**.
2. In the Controllers list, select the controller whose file services will
be restarted.
3. In the top menu bar, select Restart File Services.
1. Select the file services to restart.
* **SMB Service**
* **NFS Service**
A confirmation dialog opens, alerting that
**Restarting the file share service will disconnect all connected clients**
for the selected service (SMB or NFS).
2. Confirm proceeding with the file services restart.
## Viewing Controller Properties
### Properties
This tab display the following Properties for the selected Controller:
| **Property** | **Description** |
|------------------|----------------------------------------------------------------------------------|
| ID | Controller name (which is automatically assigned) |
| Target | The iSCSI qualified name (IQN) |
| WWPN1 | Worldwide name of the FC virtual HBA |
| WWPN2 | Worldwide name of the FC virtual HBA |
| IPSec Key | IPsec Key for secured iSCSI connectivity over IPSec |
| Encryption Set | |
| VPSA CHAP User | iSCSI CHAP authentication user name. For use when setting global CHAP on servers |
| VPSA CHAP Secret | iSCSI CHAP authentication password. For use when setting global CHAP on servers |
| Cache Size | Size of Flash Cache of this VPSA |
| Heartbeat1 | Heartbeat status between 2 virtual controllers |
| Heartbeat2 | Heartbeat status between 2 virtual controllers |
| Software Version | Virtual Controller SW build version |
### Paths
This tab lists all the paths between this virtual controller and the
attached servers. If multipathing is set, each server will show all
paths along with the number of active sessions.
For iSCSI connections, the initiator and target IQNs are listed.
For Fibre Channel connections, the initiator and target WWPN are listed.
### Virtual Networks
If the VPSA was assigned muliple Virtual Networks (See: [Managing Virtual Networks](first-steps.md#managing-virtual-networks) )
they are listed in the Controller’s south panel.
Each network is displayed with its IP address and the associated VLAN ID.
### System Usage
The System Usage Charts provide live metering of the consumption of
compute resources on the selected Controller.
The charts display the usage data as it was captured in the past 20
“intervals”. An interval length can be set to one of the following: 1
Second, 10 Seconds, 1 Minute, 10 Minutes, or 1 Hour. The Auto button lets you
see continuously-updating live metering info (refreshed every 3 seconds).
System Usage includes the following charts, detailed in the table below:
| **Chart** | **Description** |
|---------------------|--------------------------------------------------------------------------------------------------------|
| CPU Usage (%) | Average usage of all CPU cores |
| Memory Usage (%) | Used memory out of available controller memory |
| Bandwidth (KB\\s) | Total networking traffic (in KB) of read and write SCSI commands issued to the Controller, per second. |
| SSD Cache Usage (%) | Amount of Flash Cache used |
### Cache Metering
The Metering Charts provide live metering of the IO workload associated
with Flash Cache of the selected Controller.
The charts display the usage data as it was captured in the past 20
“intervals”. An interval length can be set to one of the following: 1
Second, 10 Seconds, 1 Minute, 10 Minutes, or 1 Hour. The Auto button lets you
see continuously-updating live metering info (refreshed every 3 seconds).
Controller metering includes the following charts:
| **Chart** | **Description** |
|-------------------|-------------------------------------------------------------------------------------------------------------------------------|
| IOPs | The number of read and write SCSI commands issued to the Flash Cache of the Controller, per second. |
| Bandwidth (MB\\s) | Total throughput (in MB) of read and write SCSI commands issued to the Flash Cache of the Controller, per second. |
| IO Time (ms) | Average response time of all read and write SCSI commands issued to the Flash Cache of the Controller, per selected interval. |
| Hit Rate (%) | Read and write cache hit-rate during the selected interval. |
### Logs
Displays all event logs associated with the selected Controller.
### Performance Alerts
The **Performance Alerts** tab lists the configurable alerts of the selected
Controller:
- Average CPU Usage in the last minute is above the given threshold
- Average memory consumption in the last minute is above the given threshold