minio/docs/disk-caching/README.md

Disk based caching

Disk caching can be turned on by updating the "cache" config settings for minio server. By default, this is at ${HOME}/.minio.

"cache" takes the drives location, duration to expiry (in days) and any wildcard patterns to exclude certain content from cache as configuration settings.

"cache": {
	"drives": ["/path/drive1", "/path/drive2", "/path/drive3"],
	"expiry": 30,
	"exclude": ["*.png","bucket1/a/b","bucket2/*"]
},

The cache settings can also be set by the environment variables below. When set, environment variables override any cache settings in config.json

export MINIO_CACHE_DRIVES="/drive1;/drive2;/drive3"
export MINIO_CACHE_EXPIRY=90
export MINIO_CACHE_EXCLUDE="pattern1;pattern2;pattern3"

• Cache size is 80% of drive capacity. Disk caching requires Atime support to be enabled on the cache drive.

• Expiration of entries takes user provided expiry as a hint, and defaults to 90 days if not provided.

• Garbage collection sweep of the expired entries happens whenever disk usage is > 80% of drive capacity until sufficient disk space has been freed.

• Object is cached only when drive has sufficient disk space for 100 times the size of current object

Behavior

Disk caching happens on both GET and PUT operations.

• GET caches new objects for entries not found in cache. Otherwise serves from the cache.

• PUT/POST caches all successfully uploaded objects. Replaces existing cached entry for the same object if needed.

When an object is deleted, it is automatically cleared from the cache.

NOTE: Expiration happens automatically based on the configured interval as explained above, frequently accessed objects stay alive in cache for a significantly longer time on every cache hit.

The following caveats apply for offline mode

• GET, LIST and HEAD operations will be served from the disk cache.
• PUT operations are disallowed when gateway backend is offline.
• Anonymous operations are not implemented as of now.