A method for data storage includes storing data in a set of memory blocks of a non-volatile memory. Each memory block, which holds a respective portion of the data, is classified as valid or invalid depending on whether the memory block holds a most updated version of the portion, and as anchor or non-anchor depending on whether the portion belongs to a coherent snapshot of the data. Upon recovering from a power interruption, the coherent snapshot of the data is reconstructed from the memory blocks, based on classification of the memory blocks as valid or invalid and as anchor or non-anchor.