ApsaraDB RDS for PostgreSQL offers the enhanced SSD (ESSD) storage type. This topic provides the basic information about the storage type and purchase suggestions.
Storage types
For more information about the differences in performance among storage types, see Block storage performance. The performance comparison items include the maximum capacity per disk, maximum IOPS, and maximum throughput.
The ESSD storage type meets the reliability, persistence, and read/write performance goals that are specified in Alibaba Cloud service level agreement (SLA). ESSDs use a distributed storage architecture. This architecture supports multiple data replicas to ensure data reliability. If an RDS instance runs RDS High-availability Edition and the primary RDS instance fails, a primary/secondary switchover is automatically performed within seconds.
ESSD
ESSDs offered by Alibaba Cloud deliver ultra-high performance and use the next-generation distributed block storage architecture. ESSDs are integrated with 25 Gigabit Ethernet and remote direct memory access (RDMA) technologies. ESSDs can reduce one-way latencies and process up to 1 million read and write requests at random per second. ESSDs are provided in the following performance levels (PLs):
PL1 ESSD: This is the basic PL of ESSDs.
PL2 ESSD: A PL2 ESSD delivers IOPS and throughput that are approximately twice the IOPS and throughput delivered by a PL1 ESSD.
PL3 ESSD: A PL3 ESSD delivers IOPS that is up to 20 times the IOPS delivered by a PL1 ESSD and delivers throughput that is up to 11 times the throughput delivered by a PL1 ESSD. PL3 ESSDs are suitable for scenarios in which highly concurrent requests must be processed with high I/O performance and at low read and write latencies.
View the storage type of an RDS instance
Log on to the ApsaraDB RDS console and go to the Basic Information page of the RDS instance. In the Basic Information section of the page, view the storage type of the RDS instance.
Performance items of the storage type
Item | ESSD |
I/O performance |
|
Configuration flexibility | Provides various configuration options and allows you to increase and decrease the storage capacity of an RDS instance. Note You can decrease the storage capacity of RDS instances that meet specific requirements. For more information, see Change instance specifications. |
Backup method | Provides snapshot backups. |
Time required for backup, read-only instance creation, and instance cloning | Requires a few seconds. |
Time required for storage capacity expansion | Supports online storage capacity expansion. You can expand the storage capacity of an RDS instance within a few seconds. |
Impact of storage capacity expansion | Imposes no impacts. |
Data durability | Provides 99.9999999% data reliability and supports RDS instances that run RDS Basic Edition to reduce costs. |
Purchase suggestions
You can purchase ESSDs of different PLs based on your business needs.
References
For more information about the frequently asked questions about storage capacity, see FAQ about storage capacity.