Comment by prakashsurya

Error detection can always be used, but error correction may or may not be available (it depends on the type of block). Metadata blocks are redundant even on a single drive pool; so if you just have a partial failure (e.g. overwrite a metadata block) it might be able to correct the block using another redundant copy on the same drive. Data blocks will require a redundant pool configuration, though, as these are not store redundantly by default (e.g. multiple drives in a raidz or mirror).