  It is not. S stands for Software.   This is normal with many controllers, be they hardware or software. You need OMSA installed to see the individual disks.   Problems with the S300 are usually evident in the posts. The bad rap that the S-series controllers have is well-earned.   As was listed in your other post and mentioned here, you should have OMSA installed on any Dell server you work with.
I have recently inherited a 6 year old Dell T410.  It has a S300 controller and I thought it was hardware RAID adapter.  The OS only sees the virtual disks and does seem to know there are 6 drivers install,  only the two virtual drives.  I have read quite a few posts this evening and the S300 seems to get a bad wrap but without details on way.  There is no DELL management software installed on the server,  the only 'eyes' I have on the controller is if I reboot and CTRL_R  I would love some incite.
PERC S300 hardware or software