ApsaraDB RDS for SQL Server offers the enhanced SSD (ESSD) storage type. This topic provides the basic information about the storage type and purchase suggestions.
Introduction
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, durability, and read and write performance goals that are specified in the Alibaba Cloud service level agreement (SLA). ESSDs use a distributed storage architecture. This architecture supports multiple data replicas to ensure data reliability. If you use RDS High-availability Edition or RDS Cluster Edition and the primary RDS instance fails, a primary/secondary switchover is performed within seconds.
ESSD
ESSDs are developed by Alibaba Cloud based on the next-generation distributed block storage architecture. ESSDs deliver ultra high storage performance. ESSDs are integrated with 25 Gigabit Ethernet and remote direct memory access (RDMA) technologies. ESSDs can provide lower one-way latencies than standard SSD 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.
For more information about ESSD performance, see ESSDs.
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. |
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 | ★★★★★ Requires a few minutes. |
Impact of storage capacity expansion | Transient connections occur during the storage capacity expansion process. |
Data durability | ★★★★★ Delivers 99.9999999% data reliability, supports RDS instances that run RDS Basic Edition, and reduces costs. |
Purchase suggestions
We recommend that you use ESSDs.
References
For more information about the frequently asked questions about storage capacity, see FAQ about storage capacity.