a cluster of nodes each having a processor and storage; and

a network interconnecting the nodes and connecting to a client, wherein the processors of the nodes are configured to:

record, in a persistent memory (PMEM) of a node of the cluster, metadata corresponding to input/output (I/O) write accesses having data from the client directed to a virtual disk (vdisk) of the cluster, the metadata locating the data cached in an operations log (oplog) prior to persistent storage of the data at a backend of the cluster;

index the metadata by offset ranges of the vdisk;

store a first probabilistic data structure created from the metadata in a dynamic random access memory (DRAM) of the node, wherein the first probabilistic data structure includes locations of the data cached in the oplog and drained from the oplog;

store in the DRAM, a second probabilistic data structure having the metadata locating the data cached in the oplog;

in response to an I/O access having an offset directed to the vdisk, use the second probabilistic data structure and then the first probabilistic data structure to determine whether the offset is in the metadata; and

in response to determining that the offset is in the metadata, search the metadata using the offset to locate and retrieve the data.