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Requirements for Chunkservers

Chunkservers, like all other MooseFS components, must run on a POSIX-compliant operating system.

CPU​

The MooseFS Chunkserver is a multi-threaded process, which means it can effectively utilize multiple CPU cores. For optimal performance - especially in environments with heavy I/O operations or many concurrent client requests - a CPU with a high core count is recommended. While clock speed also plays a role, a larger number of physical cores will generally provide better throughput and responsiveness in chunk-handling tasks.

RAM​

The MooseFS Chunkserver typically uses around 250 MiB of RAM to manage 1 million chunks. Actual memory usage may vary depending on system activity and configuration, but this figure provides a good baseline for estimating resource needs.

Example​

Let’s say your Chunkserver is currently using 661 MiB of RAM and, according to the MooseFS Web GUI, it is storing 3 275 062 chunks.

To estimate the memory usage per chunk:

(661 MiB * 2^20 Bytes) / 3,275,062 = ~211.63 Bytes per chunk

This means the system is using approximately 212 bytes of RAM per chunk, which is in line with the expected average. This metric can help in planning memory requirements for scaling up your storage nodes.

HDD​

Chunkserver machines should reserve some local disk space under /var/lib/mfs for local data. A typical Chunkserver process stores around 2 GiB of local metadata (such as chunk IDs and related information).

For chunk storage, each machine should have dedicated disk space — ideally several gigabytes or more. Note that only disks larger than 256 MB are recognized, and only Chunkservers reporting more than 1 GB of total free space are eligible to receive new data.

A common and effective configuration includes:

  • One small disk for the operating system and system-related operations
  • Several large disks for chunk storage, each:
    • Formatted as a single partition
    • Mounted individually
    • Mountpoints listed in mfshdd.cfg to make them available to MooseFS

We recommend using simple, stable filesystems on chunk storage disks—optimized for performance and reliability, without built-in redundancy features (e.g., journaling or mirroring), since MooseFS handles data redundancy on its own.

Avoid using hardware or software RAID for chunk storage, as it introduces unnecessary complexity and may interfere with MooseFS's built-in replication and fault-tolerance mechanisms.