What PERC controller you have on the server? Physical Disks on PowerEdge R730xd are hot swappable. If drive is online it is recommended to make drive offline first before hot swapping the drive. You can refer below link with more details on this

https://www.dell.com/support/kbdoc/en-us/000143539/poweredge-hdd-how-to-physically-replace-an-hdd-hot-swap-procedure 

thank you for replying, I updated the controller firmware and that solves it.  If I may ask a different question regarding RAID, can the RAID expand or I need to add another raid controller to add another RAID as another storage?

PERC H730P Mini (Embedded)
Firmware Ver. 25.5.8.0001

Please take a look into the user manual of your H730 and search for online capacity expansion (OCP), There are a few requirements but in general it possible to expand a diskgroup with a single VD.

PERCs supports hot swapping drives since ages for the standard front backplane. If youre 730XD have the additional drive bay than iam not sure because i have in mind that it have "blue" handles which indicated cold swap.... everything which is orange can be hot swapped.

Regards,
Joerg

H730P support expanding existing virtual disk with additional disk if your existing virtual disk supports it. You can refer below link with details

https://www.dell.com/support/manuals/en-us/poweredge-rc-h730p/perc9ugpublication/reconfigure-virtual-disks?guid=guid-aad79692-439f-4743-bfbe-1f054957cd49&lang=en-us

You can also create multiple virtual disk on same controller. So if you need another virtual disk with new drives you can also do that.