Yes that is possible, you can restart the iDRAC through the iDRAC GUI or for instance with racadm racreset. This will only restart the iDRAC and leave the OS running.
Hello,  I have Dell R610 running ESXi 5.0, with about 11VMs.  I tried to get the memory information from IDRAC web GUi in the  "system inventory" tab,  but it keeps on saying : Hardware Inventory is unavailable. Try again at a later time.   I want to reboot the IDRAC and I want to know if the reboot is possible without rebooting the ESX host and without affecting the VM running on the host.     My IDRAC is at version 1.99.    Other info, I have another server, this one is R710 and running the same Idrac 1.99 version, and from this I can get the memory information perfectly without any issue.    I thank you in advance Regards Nicolas
IDRAC 6 - reboot