Performance Metrics

There are 3 important metrics data for evaluating the performance of cloud disks:

• IOPS: Number of read and write operations per second.
• Throughput: IO flow rate read and write per second.
• IO Latency: The time from IO submission to IO completion.

In theory, the larger the IOPS and throughput, the better. The lower the latency, the better.

IOPS

IOPS (Input/Output Operations Per Second) is a measurement method used for performance testing of computer storage devices (such as Hard Disk Drives (HDD), Solid State Drives (SSD) or Storage Area Networks (SAN)), which can be viewed as the number of reads and writes per second. IOPS mainly includes 4 types of IOPS indicators according to different test tendencies: random read IOPS, random write IOPS, sequential read IOPS, and sequential write IOPS.

Throughput

Throughput is the average amount of data that a disk can successfully transmit in a unit of time. The unit of throughput is usually expressed as MB per second (MB/s or MBps).

IO latency

IO latency refers to the time spent from the issuance of an IO request to the completion of the IO request.

Performance Comparison

UDisk mainly includes three types of products: RSSD cloud disk, SSD cloud disk, and ordinary cloud disk

• RSSD Cloud Disk: It uses Nvme SSD as storage medium at the bottom layer, and RDMA for network transmission
• SSD Cloud Disk: It uses Nvme SSD as its storage medium at the bottom layer
• Ordinary Cloud Disk: It uses HDD mechanical disk as storage medium at the bottom layer

The performance comparison of the three cloud disk products is shown in the table below:

Relationship between RSSD Performance and Instance Performance

The IO performance of the virtual machine instance is linearly proportional to its CPU configuration. The more cores, the higher the storage IOPS and throughput.

• If the performance of the RSSD cloud disk does not exceed the IO storage capability of the instance, the actual storage performance is determined by RSSD cloud disk performance
• If the performance of the RSSD cloud disk exceeds the IO storage capability of the instance, the actual storage performance is determined by the storage performance associated with the instance
• If the number of instance cores is not in the table below, then the instance performance is not to exceed the maximum performance of this number of cores, for example, if the number of CPU cores is 50, then its IO storage performance is the same as 48 cores.