For production high availability, a quorum of three or more File System Manager nodes is the recommended configuration. This allows the system to maintain operation and consensus even if one node fails, preventing a single point of failure. A single node is not highly available, two nodes can lead to a split-brain scenario without a tiebreaker, and NSD servers do not host the active FSM role.

For a workload dominated by small, random reads (which are often metadata-intensive), enabling and properly sizing the fileset-specific metadata cache (mmfsconfig –metadata-cache) on the client nodes can dramatically reduce latency and improve IOPS. This keeps frequently accessed metadata locally. Increasing block size helps large sequential I/O, decreasing pagepool hurts performance, and while RDMA helps, it’s not the primary lever for metadata-heavy random read patterns.

A quarantined node is one that the cluster has automatically isolated from serving data (NSD or FSM roles) because it has detected problems, such as network issues or slow responses. However, the node remains part of the cluster, can communicate, and may automatically rejoin data services once its health is restored. It is not a permanent removal, a planned offline state, or a purely manual safe mode.

IBM Storage Scale Active-Active replication uses an inode generation number (a 64-bit counter) that is incremented with every metadata change. The replication process synchronizes this generation number. When a file is accessed on the target cluster, its generation number is compared to the cached value; if it differs, the client knows its cache is stale and must refresh data/metadata from the storage, ensuring read-after-write consistency.

Daemon Networks are a core IBM Storage Scale concept for logically segregating traffic. You define separate daemon networks (e.g., management, client, storage) during cluster configuration. This allows different TCP/IP networks or even different network adapters to be dedicated to specific cluster functions, ensuring bandwidth isolation, security, and optimal performance for each traffic type.

A disk status of ‘free’ means the disk is recognized by the cluster (it’s a managed disk), but it is not currently assigned to any storage pool or failure group. It is available and ready to be added to a pool using the `mmadddisk` command. It is not failed, not being erased, and not in active use.

IBM Storage Scale’s Role-Based Access Control (RBAC) system allows you to define custom administrative roles with specific privileges. You can create a role that grants permissions for operations like ‘CREATE_FILESET’ and ‘MANAGE_FILESET’ only on a specified file system or directory subtree, and then assign that role to the data scientists’ group, providing precise delegated administration.

Quorum nodes are critical for cluster integrity during a network partition (split-brain). They participate in a voting mechanism. For the cluster to remain operational, a partition must contain a majority (more than half) of the quorum nodes. This ensures only one partition can continue, preventing data corruption that could occur if two separated partitions both allowed writes to the same data.

The IBM Spectrum Scale Data Management (DM) service provides transparent tiering and file lifecycle management. It includes policy engines and migration modules that physically move data between storage tiers (e.g., from local flash/disk to cloud object storage) based on user-defined rules. The FSM manages metadata, FPO is for local storage optimization, and Native RAID manages local disk arrays.

For production high availability, a quorum of three or more File System Manager nodes is the recommended configuration. This allows the system to maintain operation and consensus even if one node fails, preventing a single point of failure. A single node is not highly available, two nodes can lead to a split-brain scenario without a tiebreaker, and NSD servers do not host the active FSM role.0