Hi,  It is recommended to enable the scanner.  There will be a small bit of overhead. However, you can set the scan rate ( default: 1MB/second per device) which limits the bandwidth allowed for scanning.  Setting high bandwidth may create negative impact on system performance.  Background device scanner enhances the resilience of your ScaleIO system by constantly searching for, and fixing, device errors before they can affect the system.  There are two modes, Device only and Device comparison.  Note device comparison is only available if zero padding us enabled.  Background device scanner can be enabled/disabled for a given storage pool at any time.  For new storage pools, the scanner us disabled.  Upon enabling/disabling the scanner, takes few seconds to start/stop.  Hope this helps, kind regards,
Hello, By default background device scanner is disabled. Is it recommended to enable it? Does it cause any performance overhead?
Background device scanner