Basic Definitions
Latency: Latency is simply the time it takes to retrieve data.
Cache: Cache is an in-memory storage service.
SSDs: Solid State Drives
HDDs: Hard Disk Drives
Types of Storage Services offered by Cloud Providers
Object storage : manages data in terms of blobs or objects. Each object is individually addressable by a URL. While these objects are files, they are not stored in a conventional file system.
File storage : provides network shared file storage to VMs.
Block storage : uses a fixed size data structure called blocks to organize data. 4kb is the common block size for its file system. However, block sizes of 8kb are often used by relational databases that are designed to access block storage directly.
Caches : are in-memory data stores that maintain/provide fast access to data. The latency of in-memory stores is designed to be submillisecond making them the fastest data store after SSDs