TiFlash compute nodes support dynamic disk sizing.

Enhancement

Currently, under disagg arch TiFlash compute nodes use the config storage.remote.cache.capacity to define the local capacity available for caching S3 files. When storage.remote.cache.capacity is set to 0, local caching of S3 files is disabled.

When deployed in the cloud, TiFlash compute nodes are typically deployed with exclusive disks that is not shared with any other component. In cloud environments, parameters such as EBS disk capacity can be adjusted without restarting the EC2 instance. Therefore, when disk space becomes insufficient, it may be necessary to dynamically expand the EBS volume. In such scenarios, TiFlash compute nodes should be able to adapt to the increased EBS capacity without requiring a restart, thereby utilizing the expanded disk space for larger local cache capacity.

Start by tracing how the storage.remote.cache.capacity configuration controls local S3-file caching for TiFlash compute nodes under disaggregated architecture. The work is done when setting this value to 0 still disables caching, while an expanded cloud disk can be detected and used for greater cache capacity without restarting the node.