Synchronous vs. asynchronous replication

Synchronous vs Asynchronous Replication

Native SQL Server AlwaysOn
vs
RDS Multi-AR for SQL Server Web/SE/EE HA/DR on AWS

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Published: May 1, 2016

Definition: Synchronous replication requires the bandwidth of a LAN between the servers, possibly with an extended LAN in two geographically remote computer zones. Asynchronous replication can be implemented on a low speed WAN.

The native SQL Server AlwaysOn mirroring replicates synchronously. It can work between two SQL Servers Enterprise in on-premise network or between two EC2 SQL Servers Enterprise in same AWS region. It supports Active-Active fail-over.

CloudBasic RDS Multi-AR for SQL Server on AWS was designed to support primarily hybrid on-premise to AWS RDS or EC2 SQL Server (and vice versa) cross-region replication scenarios. It replicates asynchronously over a WAN connection and tolerates degradation in connectivity (and even short downtimes of the primary or replica SQL Servers) between on-premise and AWS. It supports all versions of SQL Server, including Web Edition, and allows for deploying of a cross-region Active-Passive fail-over. More information about Active-Passive fail-over can be found at https://cloudbasic.net/aws/rds/alwayson/dr/

Synchronous vs. asynchronous replication

The primary difference between synchronous replication and asynchronous replication is the way in which data is written to the replica. Most synchronous replication products write data to primary storage and the replica simultaneously. As such, the primary copy and the replica should always remain synchronized.

In contrast, asynchronous replication products copy the data to the replica after the data is already written to the primary storage. Although the replication process may occur in near-real-time, it is more common for replication to occur on a scheduled basis. For instance, write operations may be transmitted to the replica in batches on a periodic basis (for example, every one minute). In case of a fail-over event, some data loss may occur.

 

The benefits of asynchronous replication

  • Asynchronous replication requires substantially less bandwidth than synchronous replication.
  • It is designed to work over long distances. Since the replication process does not have to occur in real time, asynchronous replication can tolerate some degradation in connectivity.

In contrast, synchronous replication allows fail-over from primary to secondary data storage to occur nearly instantaneous, to ensure little to no application downtime. However as noted above, it requires the bandwidth of a LAN between the servers, possibly with an extended LAN in two geographically remote computer zones and may also require specialized hardware (depending on the implementation).

RDS Multi-AR (Asynchronous Replication) for RDS SQL Server HA/DR

RDS\EC2 SQL Server Multi-AZ and Multi-AR (Cross-Region) Readable-Replicas for HA/DR, reporting, off-loading of primaries. On-Premise to AWS replication for Cloud HA/DR.

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You'll be in good company:

Amazing Product for RDS SQL Server replication

 

Cloudbasic RDS Always-On/Geo-Replicate for SQL Server provided us with just what we were looking for. It saved us a lot of time during our migration process by taking care of the database schema replication and keeping large amounts of data in sync. Also, the support has been amazing in terms of being available in-spite of the time zone differences. Read full review >>

Bernadette Hensley

Great product, fantastic support team!

We’re a small, growing company so our AWS budget is tight and the CloudBasic replication product is the perfect solution for our needs. This product has allowed us to implement a reliable, near real-time replication solution without resorting to expensive SQL Server/RDS replication solutions. The CloudBasic product has proven to be fast, reliable, easy to set up, use and manage.

Before our AWS migration we managed our own physical SQL Server installation and used SQL Server log shipping to sync our online and reporting databases with typical latencies of 15-30 minute range. With the CloudBasic solution our latencies are now in the 2-5 second range…  Read full review >>

Damien Hanna, Roomex Limited

CloudBasic is an AWS Rockstar!

The CloudBasic RDS Always-On/Geo-Replicate for SQL Server solution is an absolute lifesaver when working with RDS SQL Server! SQL Server on RDS falls short in a lot of aspects when it comes to replication and disaster recovery, and this solution makes the process seamless. We’re able to migrate very large amounts of data and keep the in sync while we move applications around, as well as create usable read-replicas that RDS simply doesn’t provide. Anytime we’ve run into any snags in the process, CloudBasic support has been right there available to help get things going right away. I’m truly impressed with the product and the company behind it! Read full review >>

Chris Kizziar

five-starsGreat product, simplifies architecture and hassle free

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five-starsExcellent product and support!

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I strongly recommend the product and the CloudBasic advisory support team…  Read full review >>

Dev OPS

five-starsI’m really happy I found your product

I’m really happy I found your product as there are not many options for this sort of thing with RDS and SQL Server.

 

Daniel O’Connor, OpenAgent.com.au

five-starsDoes what it says on the box, easy to use, amazing support.

I found this tool when I was looking for a way to transfer databases between our development systems and our production systems. These comprised of a mix of in house physical SQL, EC2 SQL and and RDS. Cloudbasic Geo-replicate solved this problem.

The product improvements I asked for were implemented within days allowing me to extend our use of this product into our devops continuous delivery model.

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Nick Semer, IT Consultant

five-starsSimple, Powerful, with Stellar Support

 

The software delivers what it promises. Its easy to use. The support is fantastic. We were impressed how fast they reached out to us to want to help. The software is fast, economical and affordable. It doesn’t put any stress on your source and destination databases. It seamlessly does what it does and it does it well. I highly recommend this product to anyone.

Otelz Development Team

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We were looking for a way to continuously replicate our RDS based SQL Servers from west to east coast, for disaster recovery and reporting purposes. We started from looking for a SQL Server log shipping and high availability based solution ..then found CloudBasic’s Geo-Replicate server. We launched the server from the market place, entered RDS source and destination information and within minutes were able to stream data. The secondary DBs seeded very fast, and … Read All

Radmeister, Inc.

five-starsEasy setup. Various deployment scenarios.

We were looking to utilize AWS as a fail-over site for our on-premise SQL Server based applications. We turned to the AWS Market place to find solutions to help us speed up implementation. Found this product, and within minutes were able to steam SQL Server data to an RDS SQL Server on AWS. All we had to do is enter source and destination SQL server connection strings. Then selected if we wanted a one time migration of the SQL server or also… Read full review >>

J.P., Solution Architect

five-starsWorks very well. Easy to use. Some minor issues need to be addressed.

We intended to use this software to do a one time migration of SQL databases from our co-located datacenter to AWS. Then figured it is very easy to setup continuous replication from East to West coast (AWS in California to AWS in Virginia). We currently use EC2 SQL Server Web edition in California, replicating to a small RDS Web Edition in Virginia… Read full review >>

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AnswerFirst Communications