Ancient Sparta was an interesting example of a society based on large scale slavery. Unlike the rest of Classical Greece, where slavery was an individual thing (i.e. you could choose to own a slave if you could afford one), and slavery itself was considered an unfortunate condition (being enslaved because your side lost the war, or sold to pay off debts and so on), Spartan Helots were enslaved as a conquered people, and property not of any particular Spartan, but of the Spartan State as a whole.
While this also had some pretty severe consequences for the evolution of the Spartan Polity (especially the rise of a permanent warrior class developed primarily to deal with slave revolts), the Spartans also had an extensive system of informants, fake incentives and even a ferocious secret police (the Krypteia)
So your society is likely to evolve in similar directions.
All able bodied freemen will be impressed into military service in order to provide the manpower to put down slave revolts. Slaves will be subverted so some will become willing stooges capable of informing on their fellow slaves to provide information. Sometimes, slaves might be "invited" to become soldiers or receive manumission; the ones which step forward are violenty punished or killed to ensure others don't get ideas above their station.
Finally, the Krypteia was essentially a cross between "Force Recon" and the Stasi, creeping around to observe the slaves when they didn't think they were being observed, taking notes and then swooping down to seize potential troublemakers and remove them from the rest of the population.
Of course the Spartites discovered that this was a policy of diminishing returns. As the Helot population grew and the farm income of the Spartan State increased, the Spartans were forced to redouble their efforts to keep the Helots down. Sparta evolved into a hyper militarized state, ritually declaring war on the Helots every year and with virtually no male citizens exempt from military duty and full time training. We know a lot about the Spartan military, but there is virtually no Spartan literature, arts, temple complexes or even Spartan colonies around the Aegean Sea. And of course, the Helots nurtured a simmering resentment, to the point Xenophon wrote "helots would gladly eat their masters raw", and several unsuccessful Helot revolts were recorded in history.
The Spartan advantage of extreme militarization kept them in power until after the Peloponnesian War, when Thebes, another land power, finally invaded Laconia under Epaminondas. He defeated the Spartans militarily, and then not only freed the Helots, but kept his army in Messenia long enough for the Helots to throw up fortified cities and gain enough training , weapons and equipment to successfully battle the Spartites on equal terms.
If there is no outside "power" to liberate the Helots, they may choose to revolt against their masters, but unless there is an overwhelming manpower advantage or they are led by some sort of military genius who can overcome deficits in training and equipment, success is not guaranteed at all.
