doesn't notary chains on XCH (xcp clone for viacoin) basically do what factom says it wants to do?
or am I missing something?
no one is even really using notary chains at the moment btw (although it is a nice idea)... people are building solutions for 5 years from now is what is happening
Just to expand it a bit - XCH has a "blockchain notary service" implemented and "custody chains" are in development now. Yes, this is all very close to what Factom is developing, however Factom outsources 99% of this work and data storage away from the Blockchain of choice (Viacoin, in this case) and on to their own network. You can probably roll your own in house Factom server/infrastructure too. XCH look like they will stuff everything into their Blockchain.
i don't think that is the case my understanding is that the XCH notary just puts the hash of the document(s) onto the blockchain, which is what i thought factom does as well? and the data storage could be anything from storj, maidsafe to my mom's hard drive.
My apologies, when I said "data storage" I meant storage of the hashes. I didn't mean storage of the original data, which as you mentioned could be achieved in any way imaginable. So to summarize what I tried to say earlier:
Factom = Factom Network (to notarize every document individually and establish/notarize the custody chain(s)) + Bitcoin Network (to notarize aggregations/snapshots of what has happened in the Factom Network)
Clearinghouse = Bitcoin Network (to notarize every document individually and establish/notarize the custody chains)
TL;DR Factom has a dedicated off-chain (off-Bitcoin Blockchain) notary service/network, Clearinghouse doesn't (i.e. it just uses it's Viacoin Blockchain for everything).
It all comes down to questions of price/fee, security, Blockchain Bloat, trust in the given network, etc.