Ephemeral SSD disks use the local storage of physical machines at which the instances are located. This type of storage provides block-level data access capabilities to instances. It has low latency, high random IOPS, and high throughput I/O capability.
Pay attention to the following issues when using ephemeral SSDs:
- The storage space provided by ephemeral SSDs of servers has potential single point of failure (SPOF) risks. It is recommended to implement data redundancy at the application layer to ensure data availability.
- Users cannot upgrade or downgrade the CPU, memory, and ephemeral SSD disks after purchasing.
- Since the ephemeral SSD uses the local disk of a physical server, it does not support independent attaching/detaching.
Ephemeral SSD disks provide the following features:
Under normal conditions, the access latency is in microseconds.
High random I/O performance
The maximum random IOPS is 12,000.
The maximum I/O throughput is 300 MBps.
Large storage capacity
A single ephemeral SSD provides a maximum storage space of 800 GiB.
Ephemeral SSD disks are applicable to distributed, I/O-intensive applications with redundancy and scenarios that do not require high data reliability, such as the following:
NoSQL and MPP data warehouse, distributed file systems, and other I/O-intensive applications have their own distributed data redundancy. Ephemeral SSD disks can provide low latency, high random I/O, and high throughput I/O performance.
Logs for large online applications
Large online applications can produce large amounts of log data and require high-performance storage. At the same time, the log data does not require highly reliable storage.
As the swap partition of an instance
When the memory required by an application exceeds the memory actually allocated, a swap space can be used in Linux. When the swap space is enabled, the Linux system can frequently swap in-use memory pages from the physical memory to the swap space (no matter whether it is a dedicated partition of the existing file system or a swap file). In addition, it can free up space for memory pages that require a high access speed.