Walrus implements fault tolerance by sharding and replicating your data across the network. Typically, it creates 4-5 copies of each data shard, ensuring that you can recover your data even if up to 2/3 of the network fails. Regarding the need to run multiple storage nodes: Walrus does not require you to operate multiple nodes yourself to achieve fault tolerance. It already spreads chunks of your data across various nodes in the network. This is a key difference from solutions like IPFS clusters, where users must manage their own redundancy.

To ensure private visibility when storing files on Walrus, you need to encrypt the files before uploading them, as Walrus does not provide native encryption. You can use the Seal framework, which offers threshold encryption and on-chain access control to keep the decryption logic secure while using Walrus for storage.