There are two types of scrub happened,
1> drives part of disk group
2> drives not part of disk group
To configure background scrub for disk groups
1. In the System topic, choose Action > Advanced Settings > System Utilities.
2. Set the options:
Either select (enable) or clear (disable) the Disk Group Scrub option. This option is enabled by default.
Set the Disk Group Scrub Interval (hours) option, which is the interval between background disk group scrub
finishing and starting again, from 0–360 hours. The default is 24 hours.
3. Click Apply. If you chose to disable background scrub, a confirmation panel appears. Click Apply to accept the
changes or click Cancel.
To configure background scrub for disks not in disk groups
1. In the System topic, choose Action > Advanced Settings > System Utilities.
2. Either select (enable) or clear (disable) the Disk Scrub option. This option is disabled by default.
3. Click Apply.
Regarding your 2nd question, yes you can add new drives anytime in the system and configure them as Global spare
Regarding 3rd question, make sure your MSA up to date with latest firmware.
Hope this helps!
Regards
Subhajit
I am an HPE employee
If you feel this was helpful please click the KUDOS! thumb below!
*************************************************************************