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Disk Cache Quickstart Guide 
Disk caching feature here refers to the use of caching disks to store content closer to the tenants. For instance, if you access an object from a lets say gateway s3 setup and download the object that gets cached, each subsequent request on the object gets served directly from the cache drives until it expires. This feature allows MinIO users to have
- Object to be delivered with the best possible performance.
- Dramatic improvements for time to first byte for any object.
Get started
1. Prerequisites
Install MinIO - MinIO Quickstart Guide.
2. Run MinIO gateway with cache
Disk caching can be enabled by setting the cache environment variables for MinIO gateway . cache environment variables takes the mounted drive(s) or directory paths, any wildcard patterns to exclude from being cached,low and high watermarks for garbage collection and the minimum accesses before caching an object.
Following example uses /mnt/drive1, /mnt/drive2 ,/mnt/cache1 ... /mnt/cache3 for caching, while excluding all objects under bucket mybucket and all objects with '.pdf' as extension on a s3 gateway setup. Objects are cached if they have been accessed three times or more.Cache max usage is restricted to 80% of disk capacity in this example. Garbage collection is triggered when high watermark is reached - i.e. at 72% of cache disk usage and clears least recently accessed entries until the disk usage drops to low watermark - i.e. cache disk usage drops to 56% (70% of 80% quota)
export MINIO_CACHE="on"
export MINIO_CACHE_DRIVES="/mnt/drive1,/mnt/drive2,/mnt/cache{1...3}"
export MINIO_CACHE_EXCLUDE="*.pdf,mybucket/*"
export MINIO_CACHE_QUOTA=80
export MINIO_CACHE_AFTER=3
export MINIO_CACHE_WATERMARK_LOW=70
export MINIO_CACHE_WATERMARK_HIGH=90
minio gateway s3
The CACHE_WATERMARK numbers are percentages of CACHE_QUOTA.
In the example above this means that MINIO_CACHE_WATERMARK_LOW is effectively 0.8 * 0.7 * 100 = 56% and the MINIO_CACHE_WATERMARK_HIGH is effectively 0.8 * 0.9 * 100 = 72% of total disk space.
3. Test your setup
To test this setup, access the MinIO gateway via browser or mc. You’ll see the uploaded files are accessible from all the MinIO endpoints.