Notes and Constraints

Storage space

• Centralized instances: 40 GB to 24,000 GB
• Distributed instances: 120 GB to 72,000 GB

To increase the upper limit of the storage space to 10 TB when cloud SSDs or extreme SSDs are used, contact customer service.

Connections

The minimum number is 10 and the theoretical maximum number is 262,143. The actual maximum value dynamically changes.

The maximum number of connections supported depends on memory specifications. For details, see Configuration of Maximum Connections.

IOPS

• Ultra-high I/O: a maximum of 50,000
• Extreme SSD: a maximum of 128,000

The input/output operations per second (IOPS) supported depends on the I/O performance of Elastic Volume Service (EVS) disks. For details, see the description about ultra-high I/O and extreme SSDs in Disk Types and Performance of Elastic Volume Service Service Overview.

Tags

Each instance can have up to 20 tags.

For more information, see Tags.

Free backup space

GaussDB provides free backup space of the same size as your purchased storage space.

After you pay for the storage space of your instance, you will get a backup space of the same size for free. For more information, see How Is GaussDB Backup Data Billed?

Retention period of automated backups

The default value is 7 days. The value ranges from 1 to 732 days.

For more information, see Configuring an Automated Backup Policy for Instances.

Instance name

• 4 to 64 characters long
• Must start with a letter. Only letters (case-sensitive), digits, hyphens (-), and underscores (_) are allowed.

Backup name

• 4 to 64 characters long
• Must start with a letter. Only letters (case-sensitive), digits, hyphens (-), and underscores (_) are allowed.

Parameter template name

• 1 to 64 characters long
• Only letters (case-sensitive), digits, hyphens (-), underscores (_), and periods (.) are allowed.

root permissions

Only the root user permissions are available on the instance creation page.

root password

• 8 to 32 characters long
• Must contain at least three types of the following: uppercase letters, lowercase letters, digits, and special characters. Supported characters: ~!@#%^*-_=+?,

For more information, see Resetting the Administrator Password.

Database port

The port ranges from 1024 to 39989, but the following ports that are reserved for system use cannot be used: 2378 to 2380, 2400, 4999 to 5001, 5100, 5500, 5999 to 6001, 6009 to 6010, 6500, 8015, 8097, 8098, 8181, 9090, 9100, 9180, 9187, 9200, 12016, 12017, 20049, 20050, 21731, 21732, 32122 to 32126, and 39001.

For more information, see Changing the Database Port.

Disk encryption

If you enable disk encryption during instance creation, the disk encryption status and the key cannot be changed later.

VPC

The VPC where a GaussDB instance is located cannot be changed after the instance is created.

Security group

• By default, each tenant can create up to 500 security group rules.
• It is recommended that a security group contain a maximum of 50 rules. For more information, see Configuring Security Group Rules.

System accounts

To provide O&M services, the system automatically creates system accounts when you create GaussDB instances. These accounts cannot be used by users.

• rdsAdmin: a management account with the highest permission.
• rdsBackup: a backup account. It is used for backend backup.
• rdsRepl: an account used to synchronize data from the primary instance to the standby instance.
• root: the system administrator account.
• rdsMetric: a metric monitoring account. It is used to obtain GaussDB performance metrics and report them to Cloud Eye for the tenant to view the status of GaussDB.

Database access

• To access a GaussDB instance that is not publicly accessible, the instance must be in the same VPC subnet as the ECSs.

• The ECSs must be allowed by the security group to access the target GaussDB instance.

  If a GaussDB instance and the ECSs belong to different security groups, no communication between them is established by default. To allow it, you must add an inbound rule to the GaussDB security group.

• The default port number of GaussDB instances is 8000.
• The database port can be set when a DB instance is created and can be changed after the DB instance is created.

Deployment

The servers where instances are deployed are not directly visible to you. You can only access the instances through IP addresses and database ports.

Rebooting a GaussDB instance

GaussDB instances cannot be rebooted through commands. They must be rebooted on the management console.

Querying GaussDB backups

GaussDB backup files are stored in OBS buckets and are not visible to you.

Specification changes

• By default, the specifications cannot be reduced. If you need to reduce the specifications, contact Huawei Cloud technical support.
• Before you change the instance specifications, ensure that the instance is available. If the instance or node is abnormal, or the storage space is full, you cannot perform this operation.
• During the specification change for HA (1 primary + 2 standby) instances, a primary/standby failover is triggered. During the failover, services are interrupted for about 1 minute.
• For a single-replica instance, changing instance specifications will reboot the instance and interrupt services for 5 to 10 minutes.
• Changing the CPU and memory specifications will cause the instance to reboot, and services will be temporarily interrupted during the reboot.

Failover

For centralized instances, services are unavailable for about 10 seconds when the primary node is being switched to the standby node.

Data restoration

To prevent data loss, you are advised to back up key data before data restoration.

Storage space

If the storage space of an instance is full, data cannot be written to databases. You are advised to periodically check the storage space.

Performance tuning

Performance tuning may need to reboot the instance and interrupt services.

Recycle bin management

• GaussDB allows you to move unsubscribed yearly/monthly instances and deleted pay-per-use instances to the recycle bin. You can restore an instance that was deleted up to 7 days ago from the recycle bin.
• The recycle bin is enabled by default and cannot be disabled. The deleted instances can be retained for 7 days by default.