FAQs about exclusive instances - Alibaba Cloud Developer Forums: Cloud Discussion Forums

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FAQs about exclusive instances

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More Posted time:Dec 6, 2016 13:53 PM
What is an exclusive instance?
The exclusive instance is an instance with a fixed computing capacity and balanced network performance. The product was launched by Alibaba Cloud in September 2016. Two specifications are added in the instance specification series II: the exclusive-type SN1 and exclusive-type SN2. For scenarios with higher CPU utilization and requiring more stable computation paths, the exclusive instance is an optimal choice.

What are the principle and performance features of exclusive instances?
To ensure the secular stability of computing performance within expectation, the CPU allocation policy of the exclusive instance is to allocate and maintain multiple vCPUs to the same computing core. Because of the presence of hyper-threading, threads on the same instance still compete with each other, but the computing performance of the instance stays stable within expectation and won't be influenced by the behavior on other instances on the physical server.
In comparison, the shared instance adopts a random sharing policy for vCPU allocation. The sharing mode of vCPUs will change with time based on the load behavior on other instances on the physical server while ensuring the performance to the largest extent. The vCPUs may be scheduled to different computing cores, or to the same core. When other instances on the physical server are not busy, the computing capacity by allocating vCPUs of this instance to different computing cores will surpass that of the exclusive instance. But when other instances on the physical server are all busy, the performance will be compromised significantly. Therefore, the shared instance cannot always maintain consistent computing performance. Under some circumstances, the shared instance may outperform the exclusive instance, but under some other circumstances, the shared instance will underperform the exclusive instance.

In what business scenarios are exclusive instances necessary?
• Massively Multiplayer Online Game (MMO) front ends, data analysis, and computing.
• Medium/large Web servers (high concurrency).
• Computing scenarios with a fixed performance such as high-precision coding/decoding, rendering, and gene computing with a CPU.
What limits are there for purchasing exclusive instance specifications and changing exclusive instance configurations?
• You cannot swap configurations between the general-type N1, general-type N2, memory-type E3 and exclusive-type SN1, exclusive-type SN2 of series II.
• You cannot swap configurations between series I and series II instances either.

What is the highest specification of exclusive-type instances available?
The highest specification of exclusive-type instances: 40-core, 224 GB of memory.

What network types does the exclusive-type instance support?
It supports two network types: private networks and classic networks.

What disk types does the exclusive-type instance support?
• The exclusive-type instance supports ultra cloud disks and SSD cloud disks as the system disk.
• The data disk supports basic cloud disks, ultra cloud disks and SSD cloud disks.

What image types does the exclusive-type instance support?
• The exclusive-type instance supports images of various types of operating systems.
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