Abstract: A technique protects host data. The technique involves receiving, at a local computerized node, a block of data from a host computer, the block of data including data sub-blocks. The technique further involves storing the block of data, as a dirty cache block, in a local cache of the local computerized node. The technique further involves performing a set of external caching operations to cache a set of sub-blocks in a set of external computerized nodes in communication with the local computerized node. Each external caching operation caches a respective sub-block of the set of sub-blocks in a cache of a respective external computerized node. The set of sub-blocks includes (i) the data sub-blocks of the block of data from the host and (ii) a set of checksums derived from the data sub-blocks of the block of data from the host.