Storing B-tree pages in capacity tier for erasure-coded storage in distributed data systems

A method for employing a distributed-computing system to store a set of client data blocks, wherein the system includes:

• a capacity storage tier including a first plurality of storage disks storing a capacity data object structuring the set of client data blocks as a plurality data stripes that are erasure coded (EC) and distributed across the first plurality of disks, wherein each of the plurality of data stripes includes a subset of the set of client data blocks and corresponding parity data for the subset of client data blocks;
• and
• a performance storage tier including a second plurality of storage disks storing a metadata object structuring log data as a B-tree that includes a plurality of leaf nodes and a plurality of index nodes that include pointers to each of the plurality of leaf nodes, wherein the plurality of leaf nodes encodes an address map indicating, for each client data block of the set of client data blocks, a correspondence between a logical address associated with a first layer of the system and a physical address associated with a second layer of the system,
• wherein the method comprises:
• determining a storage volume associated with the plurality of leaf nodes that are stored on the performance tier;
• in response to the storage volume of the plurality of leaf nodes stored on the performance tier is greater than a predetermined volume threshold, migrating at least a portion of the plurality of leaf nodes to one or more of the plurality of data stripes of the capacity storage;
• updating a portion of the plurality of index nodes that include pointers to the migrated portion of the plurality of leaf nodes to include updated pointers to physical addresses of the one or more of the plurality of data stripes of the capacity storage that store the migrated portion of the plurality of leaf nodes;
• and
• re-allocating a portion of the performance tier that stored the migrated portion of the leaf nodes to store additional log data.

A non-transitory computer-readable storage medium storing one or more programs configured to be executed by one or more components operating in a distributed-computing system, the one or more components having one or more processors and memory, the one or more programs including instructions and the system includes:

• a capacity storage tier including a first plurality of storage disks storing a capacity data object structuring the set of client data blocks as a plurality data stripes that are erasure coded (EC) and distributed across the first plurality of disks, wherein each of the plurality of data stripes includes a subset of the set of client data blocks and corresponding parity data for the subset of client data blocks;
• and
• a performance storage tier including a second plurality of storage disks storing a metadata object structuring log data as a B-tree that includes a plurality of leaf nodes and a plurality of index nodes that include pointers to each of the plurality of leaf nodes, wherein the plurality of leaf nodes encodes an address map indicating, for each client data block of the set of client data blocks, a correspondence between a logical address associated with a first layer of the system and a physical address associated with a second layer of the system,
• wherein the instructions are for:
• determining a storage volume associated with the plurality of leaf nodes that are stored on the performance tier;
• in response to the storage volume of the plurality of leaf nodes stored on the performance tier is greater than a predetermined volume threshold, migrating at least a portion of the plurality of leaf nodes to one or more of the plurality of data stripes of the capacity storage;
• updating a portion of the plurality of index nodes that include pointers to the migrated portion of the plurality of leaf nodes to include updated pointers to physical addresses of the one or more of the plurality of data stripes of the capacity storage that store the migrated portion of the plurality of leaf nodes;
• and
• re-allocating a portion of the performance tier that stored the migrated portion of the leaf nodes to store additional log data.