If you go to Australian Nick Reddan's site, you can get a good introduction to the deeds preserved at the Registry of Deeds, Dublin:http://members.pcug.org.au/~nickred/deeds/search_index.html
The Mormons (LDS) have microfilmed the 'memorials' from the earliest date until, I think, about 1850. However, you still have to use an index system that must have been invented by a madman. I visited the Registry (Henrietta Street) and was surprised to find that transactions involving very small leaseholding tenants were often recorded, but it is very difficult and extremely time-consuming to find them. Until a certain date, moreover, the tenant's name was not indexed, only the name of the lessor, who may only have been an agent for the 'landlord'. Searching for the parcel of land, or townland, by its name is often frustratingly complicated by the fact that the name, or the spelling, has changed or ceased to be used. If you have a great deal of patience and can go to Henrietta Street, or the Family History Library in Salt Lake City, you may be lucky. I was, and my ancestors were small farmers and Catholics. If you are very, very lucky, you may find your people on Nick Reddan's site, which is still a site-in-the-making.