Resource limitations for Simple Application Server-Simple Application Server(SAS)-阿里云帮助中心

Simple Application Server has certain limitations on product features and service performance. We recommend that you review these limitations before you use the service to ensure that it meets your business requirements. This topic describes the resource limitations for Simple Application Server.

Instances

Limit	Description
Number of instances	The default quota for the total number of Simple Application Server instances, Simple Application Load Balancer instances, Simple Container Service instances, and Simple Database Service instances per Alibaba Cloud account in a single region is 50. To request a quota increase, see View or increase instance quotas.
Virtualization software and secondary virtualization	Virtualization software and secondary virtualization are not supported.
Sound card applications	Sound card applications are not supported.
Attaching external hardware devices	You cannot attach external hardware devices, such as hardware dongles, USB flash drives, external hard drives, or USB security keys.
ICP filing service numbers	For each instance in a Chinese mainland region subscribed for three months or longer (including renewals), you can apply for up to five ICP filing service numbers.

Images

Limit	Description
Custom images	The quota for custom images per Alibaba Cloud account is three times the number of your instances, up to a maximum of 15.
Cross-account image sharing	You can share custom images with other accounts only within the same region. Cross-region sharing is not supported. Each custom image can be shared with up to 10 primary Alibaba Cloud accounts. Sharing with RAM users is not supported. You cannot share images between Alibaba Cloud accounts on the China site and the International site. When you share a custom image created from an instance that has a data disk, the data disk is not included in the shared image. For more information, see Share custom images across accounts.
Application or system images	The `/home/staragent/` and `/usr/local` directories in some images contain pre-installed software, such as `/usr/local/aegis` and `/usr/local/cloudmonitor`. This software consists of programs and library files that are environment dependencies. Do not modify these files.
Releasing custom images	When you release a Simple Application Server instance, any custom images created from it are also released.

For more information about custom images, see Manage custom images.

Storage

Limit	Description
Number of system disks per instance	1
Number of data disks per instance	A maximum of one data disk can be attached.
Data disk capacity	0 to 16,380 GiB
Data disk mount point	`/dev/vdb`
Detaching a data disk	A data disk is bound to its instance, shares the same expiration date, and cannot be detached.
Renewing a data disk	Once attached, a data disk must be renewed with its instance. You cannot renew them separately.

Snapshots

Limit	Description
Number of snapshots per instance	You can create up to three snapshots per instance.
Maximum number of snapshots per account	The snapshot quota per Alibaba Cloud account is three times the number of your instances, up to a maximum of 15.
Scheduled snapshots	You can only create snapshots manually; scheduled snapshots are not supported.
Rolling back a disk with a snapshot	Snapshots created before a system reset or an image change are retained but cannot be used to roll back the disk.
Releasing snapshots	When a Simple Application Server instance expires and is released, its snapshots are also released.
Downloading or exporting snapshots	You cannot download or export snapshots.

For more information about snapshots, see Manage snapshots.

Network

Limit	Description
Public IP address	By default, each Simple Application Server instance is assigned one public IP address. This address cannot be changed and is not retained after the instance expires.
IPv6 address	Simple Application Server does not support IPv6 addresses.
Bandwidth	Simple Application Server provides symmetrical inbound and outbound bandwidth, where traffic in both directions shares a single peak bandwidth limit specified in your plan. For example, if you purchase a plan with 200 Mbps of bandwidth, the peak inbound and outbound bandwidth are both 200 Mbps. However, the total bandwidth for both directions cannot exceed 200 Mbps. This means you cannot reach the maximum bandwidth limit for both directions at the same time. The public bandwidth specified in a Simple Application Server plan is a peak value and not a guaranteed performance commitment. During periods of high traffic, resource contention may lead to bandwidth limitations or packet loss. This service is not suitable for applications that require a guaranteed high-quality public network connection. For such applications, we recommend that you purchase an ECS instance with a fixed-bandwidth billing plan.
Firewall	You can create up to 50 firewall rules per instance. Port 25 on Simple Application Server instances is blocked for outbound email. If you need to send email, use port 465 instead. For more information, see Manage firewalls.
VPC connection	By default, all Simple Application Server instances under the same Alibaba Cloud account and in the same region can communicate with each other over the internal network. However, they cannot communicate with other Alibaba Cloud services in a VPC, such as ECS and ApsaraDB instances. To enable this communication, you must set up a VPC connection. For more information, see Manage VPC connections.