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FAQs about SSD cloud disks

Last Updated: Dec 18, 2018

What is the I/O performance of SSD cloud disks?

  • High performance: A single SSD cloud disk provides a maximum of 20,000 random reading/writing IOPS and 300 MBps throughput of storage performance.
  • IOPS=min{1200+30*disk_size, 20000}. The base is 1200 IOPS, and each GiB provides 30 random IOPS up to a maximum of 20,000.
  • Throughput=min{80+0.5*disk_size, 300} MBps. The base is 80 MBps, and each GiB adds an additional 0.5 MBps up to a maximum of 300 MBps throughput performance.

How is the data reliability of SSD cloud disks?

SSD cloud disks use Alibaba Cloud’s Apsara distributed storage technology, based on three distributed copies, which can guarantee 99.9999999% data reliability.

What scenarios are SSD cloud disks suitable for?

SSD cloud disks provide high performance and high reliability. They are suitable for I/O-intensive applications with high data reliability requirements, such as MySQL, SQL server, Oracle, PostgreSQL, and other medium and large relational database scenarios. At the same time, they are also suited to medium and large-scale development and testing environments with high data reliability requirements.

Compared to basic cloud disks, how much of a performance improvement is provided by SSD cloud disks? Can you provide specific parameters?

Compared to basic cloud disks, SSD cloud disks increase the IOPS performance more than twentyfold and increase the throughput by a factor of 8−16. Generally, it is normal for SSD cloud disk IOPS performance to fluctuate by about 10%.

What is I/O optimization? Can you upgrade existing ECS instances to I/O optimized instances?

I/O optimization provides better network capabilities for instances and cloud disks. This can guarantee that the storage performance of SSD disks can be used to its full potential.

When an SSD cloud disk is attached to an I/O optimized instance, the disk can make full use of its storage performance.

Previously purchased ECS instances do not support I/O optimization. Non-I/O optimized instances cannot be upgraded to I/O optimized instances.

Can existing basic cloud disks be replaced with SSD cloud disks?

Because SSD cloud disks use only SSD storage media, existing basic cloud disks cannot be directly replaced by SSD cloud disks.

How do you purchase SSD cloud disks? What are the prices for I/O optimized instances and SSD cloud disks?

See the SSD cloud disk and I/O optimized instance prices.

When creating an I/O optimized instance, why does it sometimes take a long time to start?

I/O optimized instances use KVM virtualization technology. If an I/O optimized instance is created using an existing custom image, the drivers must be reinstalled during startup. In most cases, startup will take less than 10 minutes.

Some custom images do not support I/O optimized instances. In this case, what should I do?

Currently, you cannot use some custom images to create I/O optimized instances. If you want to create an I/O optimized instance from such a custom image, open a ticket (you must specify the image name). Then, we will perform compatibility verification in the background. After the image is verified, you can use it to create I/O optimized instances.

After purchasing, can you upgrade the product?

It can be upgraded but cannot be resized.

After using an I/O optimized instance and SSD cloud disk, the Linux system reported an error during mounting partition.

The mount point for SSD cloud disks is /dev/vdx. This differs from /dev/xvdx for basic cloud disks. Therefore, executing previous version scripting tool will report an error. We suggest you use a new one-click partition tool,, for partitioning and formatting. Or, you can manually enter the correct mount point: /dev/vdx.

Why does the instance shut down when I use FIO to test the performance?

The fio testing tool supports the bare disk partition and filesystem method to test I/O performance. If you directly test bare disk partitions, this may damage the filesystem metadata in the bare disk partition and you will be unable to access the files in this bare disk partition. This will cause the instance down. When using the fio filesystem method to test I/O performance, this problem will not occur. Therefore, we recommend that you use the fio filesystem method to test I/O performance.

What test tools and methods should I use?

See Storage parameters and performance test.