What is an external disk
The external disk is a disk outside the server, and you can increase the disk capacity by accessing it from the server.
There is a difference whether it is Block Storage or File Storage, but by mounting it, you can deal it like a local file.
It will be used as an additional disk attached (added) to the server.
In some cases, the OS itself is placed on an external disk, in which case the disk speed of the main unit and the speed of the external disk are almost unchanged.
Since it is connected via a network, it is usually slower than a locally connected SSD, but it is often a disk that can get a considerable speed.
Although the object storage can be said to be an external disk as well, the usability is quite different because the access method and the method of reading and writing files are different, so if you run out of local disks and want to expand for the same purpose, Block Storage or File Storage are candidates for use.
What is the difference between block storage and file storage
After mounting on the server, the difference is not visible in terms of usability, but there are following differences in structure.
Features of block storage
Data can be accessed at high speed by accessing in blocks.
Because it is fast, it is suitable for parts that require transactions such as databases.
A little expensive compared to other file formats.
Basically, you can mount from only one server.
Features of File storage
High-speed file access and search by combining attribute information and directory structure.
It can be mounted from multiple servers.
Access speed is “normal” compared to block storage
Comparison of external storage of VPS companies
Here is list of external disk plans of each VPS company that provides external disks.
The unit of capacity cost is yen, and the unit of capacity is GB.
Unlike Public Cloud, VPS external storage does not have a separate charge based on IOPS (I/O access that disk can process per second).