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Data Replication Xcelerator (DRX) is a replication acceleration solution that maximizes replication performance in long-distance(DR) replication with DRBD.

The replication provided by DRBD operates synchronously or asynchronously depending on the configuration environment and purpose. A synchronization method is commonly used in local HA mirror configurations to ensure full target coherency when source node failures occur, but it impacts local I/O performance due to the nature of synchronous implementation. The asynchronous method is suitable for long-distance replication. Although the RPO is somewhat lower than the synchronous method, the replication performance and the local I/O response latency are good, so most long-distance replication is assumed to operate asynchronously. However, even if asynchronous replication does not impact local operations in architectures, the following environmental problems that compromise replication performance in WAN environments will inevitably lead to performance degradation in replication throughput.

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Necessity

In real-world WAN environments, real-time replication data transfer is hindered by the following issues

The transmission bandwidth across the WAN is very low compared to the local I/O replication

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band,

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which reduces data throughput

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and causes replication

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delays.

• Replication

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• transport protocols (TCP/IP)

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• are typically subject to transmission delays and packet losses

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• across the WAN

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• , causing delays in data retransmission.
• If

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• WAN asynchronous replication is

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DRX is a kind of proxy that directly integrates with DRBD to accommodate DRBD replicated data as a buffer in DRX, and provides optimized transmission for data transmission over the WAN interval through buffering and compression.

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• operated without resolving these issues, severe replication delays are unavoidable, and it becomes impossible to maintain the replication state if replication delays and out-of-sync conditions are repeated.

DRX performs the function of buffering the replication I/O load by implementing a sufficient level of data buffering to perform replication in a low transmission band, thereby buffering replicated I/O load, realizing data de-duplication through data compression, and transmitting data to be processed by the TCP protocol Minimizes costs and shortens the physical replication transfer time over the WAN. Compression can have compression delays depending on the compress level, but it can offset the cost of these delays because you can get a significant reduction in physical data transfer time, and you get maximum compression performance when using dedicated compression boardslow transmission bands. It also implements real-time data deduplication through data compression to minimize the data transmission cost that the TCP protocol needs to handle and shorten the physical replication transmission time along the WAN section. This is a traditional WAN optimization approach, and DRX implements multi-channel simultaneous replication acceleration with high-level compression.DRX provides high-performance, real-time data encryption (AES 128-bit) at the same time with this compression, providing an effective solution to problems such as data leaks that can occur when important data of a company goes through the WAN transmission intervalin addition, it implements compressed, encrypted (AES 128 bit) real-time transmission in multichannel to achieve optimal multichannel replication acceleration.

Replication uses DRX buffering to accomplish this, rather than performing buffering directly as data is transferred. Because performing large amounts of buffering at the kernel layer can have a systemic impact, it makes sense to offload buffering to a separate proxy(DRX).

The following figure shows how the interworking between DRX and DRBD work together.

1.2. 네트워크 구성

DRX는 기본적으로 로컬 DRX와 원격 DRX의 2 프록시 구조로 구축하며 버퍼링, 압축, 암호화의 기능은 로컬-원격 DRX 구간(WAN 구간)내에서 구현되어 복제 환경에 투명하게 기능 합니다. 이러한 투명성은 복제 환경과의 연동 시 유연함을 제공하여 다음 그림과 같이 다양하게 구성할 수 있는 뛰어난 확장성을 제공합니다.

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replication.

Network Configuration

By default, DRX is deployed in a two-proxy structure: a local DRX and a remote DRX. It implements the functions of buffering, compression, and encryption within the 2-proxy section, so it functions transparently to the replication environment. This transparency provides flexibility in interfacing with the replication environment, providing excellent scalability that can be configured in various ways as shown in the following figure.

• Local configuration: Install and operate both replication and DRX in your production environment.
• Dedicated: Operate with multi-channel replication via a separate DRX-dedicated machine.
• Mixed configuration: Operate a mix of local and dedicated.