Raid 5 Drive Error

I assume you have a PERC and not a S120 within your Server

1. Set the drive offline if possible
2. swap the broken disk agains a new one
3. check if rebuild kicks in otherwise assign the Hotspare status the new disk

@Origin3k​  Yes, All disk are under PERC.
1. If Swaping the 3 problematic disk with new 3 , Rebuild is run automatically? for this, any change from raid(ctrl+r) option.

@Network_khor​ 

you need to do one disk after another.   A Raid5 only survive one missing disk so you can only replace one at a time.

If the rebuild starts automaticly it "depends". But it doesn matter because i told you that when it not starts automaticy you need to assign the Hotspare status to the new disk and assign the Hotspare to the given Raidset.

Regards,
Joerg

@Origin3k​
1.  If I configure hotspare with existing raid 5, is possibility missing any data of raid 5 volume?

No.

If your R720 is as 12 bay unit you can insert the spare disk right now when the server is up and running.    IIRC the iDrac supports the PERC in later version so you need to take a look to the Dell OpenManageServerAdministrator(OMSA). OMSA is available for Windows and Linux.

Otherwise just reboot the server and open the PERC menu.

A Hotspare can be a global or dedicated one. Depends on the number of Raidsets and your needs.

Regards,
Joerg