Frequently asked questions about SSD cloud disks and I/O optimization issues

The content of this article is about common problems of SSD cloud disks and I/O optimization issues. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

SSD cloud disk FAQ

1. What kind of I/O performance does SSD cloud disk have?

High performance: A single SSD cloud disk has a maximum storage performance of 20,000 random read and write IOPS and 300 MBps throughput.

IOPS=min{1200 30*capacity, 20000}, starting with 1200 random IOPS, providing 30 random IOPS per GiB, with a maximum of 20000.

Throughput=min{80 0.5*capacity, 300}MBps, starting at 80 MBps, increasing by 0.5 MBps per GiB, with a maximum throughput performance of 300 MBps.

2. What is the data reliability of SSD cloud disk?

SSD cloud disk adopts Alibaba Cloud Feitian distributed storage technology and is based on the distributed three-copy mechanism, which can guarantee 99.9999999% data reliability.

3. What application scenarios are suitable for SSD cloud disks?

SSD cloud disk has the characteristics of high performance and high reliability, and is very suitable for I/O-intensive applications that require high data reliability, such as MySQL, SQL Server, Oracle, PostgreSQL and other medium and large-scale applications. Relational database scenarios are also applicable to medium and large development and testing environments with high data reliability requirements.

4. How much better is the performance of SSD cloud disks compared to ordinary cloud disks? Can you provide specific parameters?

Compared with ordinary cloud disks, SSD cloud disks have a 20-fold improvement in random IOPS performance and an 8-16-fold improvement in throughput. Under normal circumstances, it is normal for the IOPS performance of an SSD cloud disk to fluctuate by about 10%.

5. What is the concept of I/O optimization? Can I upgrade existing ECS ​​instances to I/O optimized instances?

I/O optimization provides better network capabilities between instances and cloud disks, ensuring the storage performance of SSD cloud disks.

For I/O-optimized instances, you can obtain the full storage performance of the SSD cloud disk when mounting an SSD cloud disk.

Purchased stock ECS instances do not support I/O optimization. For non-I/O optimized instances, upgrading to I/O optimized instances is not supported.

6. Is it supported to replace the original ordinary cloud disk with an SSD cloud disk?

Since SSD cloud disks are implemented using all SSD storage media, it is not supported to directly replace existing ordinary cloud disks with SSD cloud disks.

7. How to purchase SSD cloud disks, and what is the price of I/O optimized instances and SSD cloud disks?

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

8. Why do I/O-optimized instances sometimes take longer to start?

I/O-optimized instances use KVM virtualization technology. If you use an existing custom image to create an I/O-optimized instance, there will be a process of reinstalling the driver during startup, causing the startup time to expire. long, in most cases within 10 minutes.

9. Some custom images do not support the creation of I/O-optimized instances. What should I do?

Currently, some custom images do not support the creation of I/O-optimized instances. If you want to use such custom mirrors to create I/O-optimized instances, please submit a work order request ( The image name needs to be specified), Alibaba Cloud will perform compatibility verification in the background, and it can be used after passing the verification.

10. Does it support upgrades after purchase?

Supports upgrade and expansion.

11. After using I/O optimized instances and SSD cloud disks, the Linux system reports an error when mounting the partition.

The mount point of the SSD cloud disk in the Linux system is displayed as /dev/vdx, which is different from the mount point /dev/xvdx of a normal instance, so before executing the tool The script will error. It is recommended that you use the new one-click partition tool: tool: auto_fdisk_ssd.sh to format the partition, or write the correct mount point /dev/vdx when doing it manually.

12. Why does the instance crash when I use fio to test performance?

fio This testing tool supports two methods of testing I/O performance: bare disk partition and file system. If you directly test the bare disk partition, the file system metadata in the bare disk partition may be destroyed, and accessing files in the bare disk partition may fail, causing the instance to crash. When testing performance using the fio file system method, the above problems do not exist, so we recommend using the fio file system method to test I/O performance.

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