Limits and quotas on ECS resources - Elastic Compute Service

Specific limits are posed on Elastic Compute Service (ECS) features and service performance. Before you use ECS, we recommend that you obtain the corresponding limits, plan in advance, and apply for a higher quota to ensure that the ECS resources can meet your business requirements. This topic describes the limits on ECS and how to apply for extensions on these limits.

Overview

ECS has the following limits:

Only ECS Bare Metal Instance families and Super Computing Cluster (SCC) instance families support secondary virtualization. Other ECS instance families do not support the installation of virtualization software and secondary virtualization.
ECS does not support sound card applications.
External hardware devices, such as hardware dongles, USB flash drives, external hard disks, and bank U keys, cannot be directly attached to ECS instances. Software verification methods, such as software dongles and two-factor authentication based on one-time passwords, can be used.
ECS does not support multicast protocols. We recommend that you use unicast protocols.
Simple Log Service does not support 32-bit Linux ECS instances.
For information about the ECS instances supported by Simple Log Service, see Install Logtail on a Linux server and Install Logtail on a Windows server.
Before you apply for Internet Content Provider (ICP) filings for websites that are deployed on your ECS instances, make sure that the instances meet ICP filing requirements. You can apply for only a limited number of ICP filing service identification numbers for each ECS instance. For more information, see Check the instance for ICP filing and access information.
Specific software or application licenses must be bound to the hardware of ECS instances. After data is migrated from one instance to another, hardware information may change and invalidate the licenses.

Instance limits

Item	Requirement or limit	Adjustable
Permissions to create ECS instances	To create ECS instances within the Chinese mainland, you must first complete real-name verification.	N/A
Instance quota by region, zone, instance type, billing method, and network type	The instance quota varies based on the instance type. You can view the instance quota items in the Quota Center console.	Go to the Quota Center console.
Maximum number of subscription instances that you can purchase at a time	View the quota in the Quota Center console.	Go to the Quota Center console.
Maximum number of launch templates that can be created in an account	View the quota in the Quota Center console.	Go to the Quota Center console.
Maximum number of versions of each launch template in an account	View the quota in the Quota Center console.	Go to the Quota Center console.
Permissions to change the billing method from pay-as-you-go to subscription	You cannot change the billing method of instances of retired instance types from pay-as-you-go to subscription. For more information, see Retired instance types.	N/A
Permissions to change the billing method from subscription to pay-as-you-go	Your ECS usage determines whether the billing method of instances can be changed from subscription to pay-as-you-go. If you change the billing method from subscription to pay-as-you-go, a refund may be made. Each account has a maximum monthly refund amount. Details of the refund are displayed on the Switch to Pay-as-you-go page in the ECS console.	N/A

Reserved instance limits

Item	Requirement or limit	Adjustable
Maximum number of regional reserved instances in an account	20	Submit a ticket.
Maximum number of zonal reserved instances per zone in an account	20	Submit a ticket.
Instance types that support reserved instances	The following instance families support reserved instances: General-purpose instance families: g7, g7a, g6e, g6, g5, g5ne, and sn2ne Compute-optimized instance families: c7, c7a, c6e, c6, c5, ic5, and sn1ne Memory-optimized instance families: r7, r7a, r6e, r6, r5, re6, re4, and se1ne Big data instance family: d2s Instance families with local SSDs: i3, i3g, i2, i2g, and i2gne Instance families with high clock speeds: hfg7, hfc7, hfr7, hfg6, hfc6, hfr6, hfg5, and hfc5 GPU-accelerated compute-optimized instance families: gn7, gn6i, gn6e, gn6v, gn5, and gn5i ECS Bare Metal Instance families: ebmgn7, ebmgn6i, ebmgn6e, ebmg6, ebmc6, ebmr6, ebmhfg6, ebmhfc6, and ebmhfr6 Burstable instance families: t6 and t5	N/A

Note

For more information, see the Limits section of the "Overview" topic.

Savings plan limits

Item	Requirement or limit	Adjustable
Maximum number of savings plans in an account	40	N/A
Instance types that support savings plans	Savings plans are not supported by the retired instance types, including t1, s1, s2, s3, m1, m2, c1, and c2.	N/A

For more information, see What is a savings plan?

Block storage limits

Item	Requirement or limit	Adjustable
Permissions to create pay-as-you-go disks	To create disks within the Chinese mainland, you must first complete real-name verification.	N/A
Maximum number of system disks on a single instance	1	N/A
Maximum number of data disks on a single instance	You can attach up to 64 data disks to a single ECS instance. The maximum number of disks that can be attached to an instance varies based on the instance type. For more information, see Overview of instance families. Note You can attach only one system disk and up to 16 data disks to an instance when you create the instance. If the instance requires additional data disks, attach more data disks after the instance is created. To query the maximum number of disks that can be attached to an instance of each instance type, you can call the DescribeInstanceTypes operation.	N/A
Capacity of all disks	The quota of the disk capacity varies based on the disk category. You can view the quota in the Quota Center console.	Go to the Quota Center console.
Capacity of a single basic disk	5 GiB to 2,000 GiB	N/A
Capacity of a single standard SSD	20 GiB to 32,768 GiB	N/A
Capacity of a single ultra disk	20 GiB to 32,768 GiB	N/A
Capacity of a single Enterprise SSD (ESSD)	PL0 ESSD: 1 GiB to 65,536 GiB PL1 ESSD: 20 GiB to 65,536 GiB PL2 ESSD: 461 GiB to 65,536 GiB PL3 ESSD: 1,261 GiB to 65,536 GiB	N/A
Capacity of a single ESSD AutoPL disk	1 GiB to 65,536 GiB	N/A
Capacity of a single ESSD Entry disk	10 GiB to 32,768 GiB	N/A
Capacity of a single local SSD	5 GiB to 800 GiB	N/A
Capacity of all local SSDs on a single instance	1,024 GiB	N/A
Capacity of a single system disk	Windows Server: 40 GiB to 2,048 GiB FreeBSD: 30 GiB to 2,048 GiB Linux distributions excluding FreeBSD: 20 GiB to 2,048 GiB Note Basic disks are the previous generation of disks that are unavailable for purchase. If you use basic disks as system disks, the capacity of each basic disk is up to 500 GiB.	N/A
Permissions to attach new local disks to instances that are equipped with local disks	You cannot attach new local disks to instances that are already equipped with local disks.	N/A
Permissions to change the configurations of instances that are equipped with local disks	You can change only the bandwidth configurations of instances that are equipped with local disks.	N/A
Mount point of the system disk on a Linux instance	/dev/vda	N/A
Mount points of data disks on a Linux instance	The mount points are named based on the number of data disks: 1st to 25th data disks: /dev/xvd[b-z]. From the 26th data disk on: /dev/xvd[aa-zz]. For example, the 26th data disk is named `/dev/xvdaa`, the 27th data disk is named `/dev/xvdab`, and so on.	N/A

Note

Block storage capacity is measured in binary units. The multiple of two neighboring binary units is 1,024. For example, 1 GiB equals 1,024 MiB.

SCU limits

Item	Requirement or limit	Adjustable
Maximum capacity that you can purchase for a storage capacity unit (SCU)	50 TiB	Submit a ticket.
Maximum number of SCUs that you can purchase in a region	100	N/A
Resource types that support SCUs	ESSDs, standard SSDs, ultra disks, and basic disks File Storage NAS Capacity and NAS Performance Standard snapshots Object Storage Service (OSS) Standard, Infrequent Access, and Archive storage classes Cloud Backup backup storage capacity Photo and Drive Service (PDS)	N/A

Snapshot limits

Item	Requirement or limit	Adjustable
Maximum number of manual snapshots that can be retained for a single disk	256	N/A
Maximum number of automatic snapshots that can be retained for a single disk	1,000	N/A
Maximum number of automatic snapshot policies that can be retained per region in an account	100	N/A

Image limits

Item	Requirement or limit	Adjustable
Maximum number of custom images in an account	View the quota in the Quota Center console.	Go to the Quota Center console.
Maximum number of users with whom a single image can be shared	View the quota in the Quota Center console.	Go to the Quota Center console.
Support of instance types for images	Instance types that have 4 GiB or more of memory do not support 32-bit images.	N/A

SSH key pair limits

Item	Requirement or limit	Adjustable
Maximum number of SSH key pairs per region in an account	500	N/A
Images that support SSH key pairs	Linux images only.	N/A

Public bandwidth limits

From November 27, 2020, the maximum bandwidth available to create ECS instances or change the configurations of ECS instances is subject to the throttling policy for your account. To increase the maximum bandwidth value, submit a ticket. The following throttling policies apply:

In a single region, the sum of actual maximum bandwidths of all ECS instances that use the pay-by-traffic billing method for network usage cannot exceed 5 Gbit/s.
In a single region, the sum of actual maximum bandwidths of all ECS instances that use the pay-by-bandwidth billing method for network usage cannot exceed 50 Gbit/s.

Item	Requirement or limit	Adjustable
Maximum inbound bandwidth per instance	If the purchased maximum outbound bandwidth is less than or equal to 10 Mbit/s, Alibaba Cloud allocates an inbound bandwidth of 10 Mbit/s. If the purchased maximum outbound bandwidth is greater than 10 Mbit/s, Alibaba Cloud allocates an inbound bandwidth that is equal to the purchased maximum outbound bandwidth.	N/A
Maximum outbound bandwidth per instance	Pay-by-traffic billing method: Subscription instance: 200 Mbit/s Pay-as-you-go instance: 100 Mbit/s Pay-by-bandwidth: 200 Mbit/s Note The maximum outbound bandwidth of a single instance is also limited by the network baseline bandwidth (Gbit/s) and network burst bandwidth (Gbit/s) of the corresponding instance type. For more information, see Overview of instance families.	N/A
Changes of the assigned public IP address of an instance	The public IP address of an instance can be changed within 6 hours after the instance is created and can be changed up to three times.	N/A

Important

When the pay-by-traffic billing method for network usage is used, the maximum inbound and outbound bandwidth values are used as upper limits of bandwidths instead of guaranteed performance specifications. In scenarios where demand outstrips resource supplies, these maximum bandwidth values may not be reached. If you want guaranteed bandwidths for your instance, use the pay-by-bandwidth billing method for network usage.

Security group limits

Item	Requirement or limit on basic security groups	Requirement or limit on advanced security groups
Maximum number of security groups in an account	View and change the quota in the Quota Center console.	The limit is the same as the limit on basic security groups.
Maximum number of ECS instances of the classic network type that can be contained in a security group of the classic network type	1,000 Note If more than 1,000 instances of the classic network type require mutual access over the internal network, you can assign the instances to multiple security groups and allow mutual access among the security groups.	Advanced security groups do not support the classic network.
Maximum number of ECS instances of the Virtual Private Cloud (VPC) type that can be contained in a security group of the VPC type	This limit varies based on the number of private IP addresses that can be contained in the security group.	No limit.
Maximum number of security groups to which an ECS instance can belong	5 Note To change the maximum number of security groups to which an ECS instance can belong, submit a ticket. You can change the limit to 4 or 10. Then, the quota for the number of rules per security group is adjusted accordingly.	The limit is the same as the limit on basic security groups.
Maximum number of security groups to which an elastic network interface (ENI) of an ECS instance can belong
Maximum number of inbound and outbound rules in a security group	200 Note If you increase the quota for the number of security groups per ECS instance, the quota for the number of rules per security group decreases. The product of the following quotas cannot exceed 1,000: the quota for the number of security groups per ECS instance and the quota for the number of rules per security group. For example, if the quota for the number of security groups per ECS instance is 4, 5, or 10, the corresponding quota for the number of rules per security group is 250, 200, or 100, as verified by using the following formulas: 4 × 250 = 1,000, 5 × 200 = 1,000, and 10 × 100 = 1,000. If prefix lists are referenced in security group rules, the maximum numbers of entries in the prefix lists count towards the quota for security group rules. For example, assume that a prefix list can contain a maximum of 100 entries. If the prefix list is referenced in a security group rule, the prefix list counts as 100 rules for the security group, regardless of the number of existing entries in the prefix list.	The limit is the same as the limit on basic security groups.
Maximum number of inbound and outbound rules in all security groups to which an ENI belongs	1,000	The limit is the same as the limit on basic security groups.
Maximum number of rules that reference security groups as authorization objects (sources or destinations) in a security group	20	0. You cannot add rules that reference security groups as authorization objects (sources or destinations) to an advanced security group, or reference advanced security groups as authorization objects (sources or destinations) in rules.
Maximum number of private IP addresses that can be contained in a security group of the VPC type	6,000 Note You can view the quota in the Quota Center console. If more than 6,000 private IP addresses that are assigned to ECS instances require mutual access over the internal network, you can assign the ECS instances to multiple security groups and allow mutual access between ECS instances in the security groups.	65,536
Internet access port	For security purposes, port 25 is disabled on ECS instances by default. We recommend that you use the SSL port instead to send emails. In most cases, the SSL port is port 465.	The limit is the same as the limit on basic security groups.

Prefix list limits

Item	Limit	Adjustable
Maximum number of prefix lists per region in an account	100	N/A
Maximum number of entries in a single prefix list	200	N/A
Maximum number of resources that can be associated with a prefix list	1,000	N/A

Network Connectivity Diagnostics limits

Item	Limit	Adjustable
Maximum number of diagnostic paths in a single region	100	N/A
Maximum number of diagnostic tasks in a single region	1,000	N/A
Maximum number of diagnostic tasks that can be concurrently executed in a single region	5	N/A

Deployment set limits

Item	Requirement or limit	Adjustable
Maximum number of deployment sets in an account	View the quota in the Quota Center console.	Go to the Quota Center console.
Maximum number of instances that can be contained in a single deployment set	For more information, see Deployment set.	N/A
Instance types that support deployment sets	You can call the DescribeDeploymentSetSupportedInstanceTypeFamily operation to specify the deployment strategy and get information about the supported instance families.	N/A

Cloud Assistant limits

Item	Limit	Adjustable
Maximum number of Cloud Assistant commands in an account	View the quota in the Quota Center console.	Go to the Quota Center console.
Output size of a Cloud Assistant command execution task
Retention period of a Cloud Assistant command execution record
Maximum number of the activation codes that can be used to register Cloud Assistant managed instances
Maximum number of instances on which a command can be run in an execution

ENI limits

Item	Limit	Adjustable
Maximum number of secondary ENIs that can be created in an account	View the quota in the Quota Center console.	Go to the Quota Center console.

Tag limits

For information about the limits on tags, see the Limits section of the "Tag overview" topic.

API limits

Item	Limit	Adjustable
Rates of ECS API operations	To view the rate quotas of ECS API operations, go to the API Rate Limits page for ECS in the Quota Center console.	N/A

Note

For information about the limits on VPCs, see Limits and quotas.