Constant Replicator: An Introduction

Transcription

1 Data Availability Storage Software Constant Replicator: An Introduction Configurations, Applications and Solutions of Constant Replicator A White Paper A Constant Data Technology Document August 2004

2 Copyright and Trademark Information Copyright Constant Data, Inc. All rights reserved. Unpublished -- Rights reserved under the copyright laws of the United States. RESTRICTED RIGHTS LEGEND Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in Technical Data and Computer Software clause at DFARS IMPORTANT NOTE TO USERS While every effort has been made to ensure the accuracy of all information in this document, Constant Data assumes no liability to any party for any loss or damage caused by errors or omissions or by statements of any kind in this document, its updates, supplements, or special editions, whether such errors are omissions or statements resulting from negligence, accident, or any other cause. Constant Data further assumes no liability arising out of the application or use of any product or system described herein; nor any liability for incidental or consequential damages arising from the use of this document. Constant Data disclaims all warranties regarding the information contained herein, whether expressed, implied or statutory, including implied warranties of merchantability or fitness for a particular purpose. Constant Data makes no representation that the interconnection of products in the manner described herein will not infringe on existing or future patent rights, nor do the descriptions contained herein imply the granting or license to make, use or sell equipment constructed in accordance with this description. Constant Data reserves the right to make changes without further notice to any products herein to improve reliability, function, or design. TRADEMARKS The Constant Data company name the Constant Data logo, the Constant Replicator, the OnDemand Replicator, the Constant HA Cluster, and the Sync2NAS product names are trademarks of Constant Data, Inc. which may be registered in some jurisdictions. All other brands and product names are trademarks or registered trademarks of their respective holders. The Constant Data name and swoosh logo, Constant Replicator, Constant Replicator DB, Constant HA Cluster toolkit, On-Demand Replicator and the Sync2NAS product names, are trademarks of Constant Data, Inc. All other brands and product names are trademarks or registered trademarks of their respective holders. Information supplied by Constant Data, Inc. is believed to be accurate and reliable. Constant Data, Inc. assumes no responsibility for any errors that appear in this white paper. All materials in this document are (and shall continue to be) owned exclusively by Constant Data, Inc. or other respective third party owners and are protected under applicable copyrights, patents, trademarks, trade dress and/or other proprietary rights. All right, title and interest not expressly granted is reserved to Constant Data, Inc. Constant Data, Inc. reserves the right, without notice, to make changes in product design or specification. Constant Data, Inc. is a member of SunTone and is applying for product certification. The Constant Replicator software product is a RedHat Certified Application, Novell/SUSE Certified Application, comprehensive IBM TotalStorage proven and IBM ServerProven. Headquarters Constant Data, Inc th Avenue South Hopkins, Minnesota Copyright 2004 Constant Data, Inc. Page 2 of 10

3 Table of Contents 1. Introduction Constant Data s Real-Time Data Replication Architecture Application Independence Successful Configurations Bi-Directional Configuration Hot-Standby Configuration Cascaded Configuration One-to-many Configuration Many-to-one Configuration Many-to-many Configuration Successful Applications Improved Backups Server Migrations and Data Migrations Simple Uni-Directional Replication combined with HA Cluster Long Distance Uni-Directional Replication of HA Clusters Bi-directional data replication between two servers on local area networks Bi-directional data replication between multiple servers on local area networks Bi-directional data replication over long distances Successful Solutions Storage Consolidation Storage Consolidation with an Integrated Failover Solution Content Distribution Universal Data Availability with Failover Universal Data Availability with Failover and Consolidation Conclusion Technical Highlights Full-Featured Product Evaluation Copyright 2004 Constant Data, Inc. Page 3 of 10

4 1. Introduction The following document describes common installed configurations of Constant Data s real-time data replication software solution - Constant Replicator. This paper presents a few examples how Constant Replicator can be used in an enterprise s existing heterogeneous IT environment. Constant Replicator is able to replicate between two server, from one server to many server (1:N), from many servers to one servers (N:1), and from many servers to many servers (M:N). 2. Constant Data s Real-Time Data Replication Architecture Constant Data s data replication software, Constant Replicator, is a hybrid real-time software solution, combining both synchronous and asynchronous replication technology. In synchronous operations, data is written on the primary storage system then the data is written on the remote system. The synchronous operation is completed only after the data has been written to all storage systems. The advantages of this model are the guaranteed transfer of data changes from the local to the remote server, because the system is not allowed to proceed until the data is successfully committed to all storage systems and 100% synchronized. The disadvantages are distance limitations, a slow local response time of applications due to the higher server overhead and the higher risk of a break down, due to its sensitivity to latency, speed and bandwidth. In asynchronous operations, the order is chronological inverse of synchronous replication. First, the data is written to the primary storage system and then sent to a remote or secondary storage system at a later point in time. The asynchronous operation is usually unaware, if the data has been delivered to the secondary site or not. The advantages of asynchronous over synchronous replication are no distance limitations, a better performance due to low network overhead, and a higher degree of scalability than synchronous replication. The disadvantage can be seen in the lower level of guaranteed data transfer from the primary to the secondary storage system. In asynchronous operations, the secondary storage system does not always have an exact copy of the primary system, because the system allows the user to proceed with the operation. Continues proceeding in operations at the primary site opens a big window of vulnerability, due to the point in time snapshot. In other words, the moment the system starts replicating the data to the secondary site, the data is already outdated because the primary site continues its operations. It also takes the same amount of time to write the data at the secondary storage system than it took to write at the primary site. The window of vulnerability is based on this point in time snapshot and increases dramatically with the size of the replicated file. The bigger the file, the longer the replication process and therefore the window of vulnerability! Constant Data s hybrid replication software, changes data first on the source and starts to replicate these changes immediately with little or no lag time to the destination server. The application on the primary site is allowed to proceed, but in the meanwhile the data gets constantly synchronized with the secondary site. Constant Replicator reduces the window of vulnerability through real-time hybrid data mirroring technology. Real-time replication solutions have a constant lag time, which is independent of the file size. In case of Constant Replicator, the remote copy overlaps with the local copy, reducing the lag time and eliminating the dependence on the underlying file system size. Normal asynchronous solutions start replicating after local changes are finished on the local server. It also abolishes the restrictions of synchronous solutions. It provides a higher degree of scalability and imposes low server overhead, which results in better local system performance. It also eliminates the limits of high latency, long distance and unstable network environments. 3. Application Independence Constant Replicator works on commodity hardware. It installs on existing server and is platform independent. The replication software allows enterprises to use their existing operating system and even complements the installed operating system. Its Application Programming Interface (API) allows the software to be fully embedded Copyright 2004 Constant Data, Inc. Page 4 of 10

5 in the operating software and IT environment. The API enables IT staff to configure and monitor the software from any machine in the network running Constant Replicator. Constant Replicator supports any file system, network file system (NFS), or any proprietary protocol a customer may have developed in house. It also fits in existing direct attached storage (DAS), network attached storage (NAS) and in storage area networks (SAN) environments. 4. Successful Configurations The following examples provide an overview of configurations successfully used by Constant Data customers when configuring Constant Replicator continuous real-time data replication software in their server and network infrastructures. 4.1 Simple Uni-Directional Configuration Simple Uni-Directional Data Replication replicates data from one server (Source) to another server (Destination). In this configuration, the source server is the primary server and the destination server is a hot-standby server. 4.1 Bi-Directional Configuration Bi-Directional Data Replication connects two server using a local area network (LAN) or wide area network (WAN). It automatically mirrors data between existing servers to maintain enterprise-wide data consistency using existing networks. 4.2 Hot-Standby Configuration A Hot-Standby for Disaster Recovery is used to keep data available in the event of a disaster. If one of the two servers fails, data is immediately available due to the replica server. A unique feature of Constant Data s software solution allows data to be usable on both the master and remote/backup server with guaranteed data integrity, regardless of the distance between the servers. 4.3 Cascaded Configuration Cascaded Data Replication distributes content between servers by replicating among the participating servers. It allows each server to be configured as both a source and/or a destination. 4.4 One-to-many Configuration 4.5 Many-to-one Configuration One-To-Many Real-Time Guaranteed Data Distribution replicates data from one server to many server that run on several heterogeneous operating platforms like Linux, UNIX, Solaris, etc. The configuration solution enables geographically dispersed organizations to instantly and effectively access the same data, regardless of location. Many-To-One Real-Time Storage Consolidation allows an organization to consolidate many servers in realtime in a heterogeneous environment to a single destination server. The configuration solution enables an organization to mirror many remote servers to a central data center where the data can be consolidated and stored. This process reduces the operating cost and improves the efficiency of an organization by saving significant resources due to effectively managed data in central data centers and the consolidation of data and backups at one remote location. Copyright 2004 Constant Data, Inc. Page 5 of 10

6 4.6 Many-to-many Configuration Many-To-Many Real- Time Data Availability solution distributes content between servers by replicating among the participating servers. Data at one location is immediately available at all the other locations in the network. Any analysis or transformation performed on the data will be immediately available within the network. Constant Replicator mirrors data between different operating systems with its true-cross platform capabilities. It also preserves security ACL metadata between Solaris and Linux servers, making it a good solution for data migration. 5. Successful Applications Constant Data improves operational efficiency and eliminates downtime with high performance data availability solutions. The solutions minimize risk, improve business processes and grow with enterprise to the next level. Constant Data s enterprise software makes the transition simple, and hassle-free. 5.1 Improved Backups Real-time data replication enhances existing backup strategies by maintaining an up-to-date centralized online backup available for immediate access in the event of a disaster or unplanned service outage. The destination server is maintained through real-time data replication and can be archived to tape from the destination server with existing backup technologies and no impact on primary server. 5.3 Simple Uni-Directional Replication combined with HA Cluster The following example illustrates simple unidirectional replication combined with a high availability cluster manager to create a HA Cluster. In this solution, a cluster manager controls the role of destination servers. One server actively assumes the role of a source and the other assumes the role of the destination as a passive hot-standby. Upon a failure of the primary active server, the passive standby server automatically takes over the role of the primary server. 5.2 Server Migrations and Data Migrations Constant Data's real-time replication products install and integrate easily in existing IT environments and guarantee data mirroring over existing networks in mixed operational environments. The Constant Replicator product line maintains a reliable, stable infrastructure to keep data synchronized by providing symmetric data mirroring between production UNIX servers and replacement Linux servers. There is no need to take the servers offline or install special hardware. Constant Data s products allow enterprises to migrate from their existing Solaris servers to new Linux servers. Desktop clients usually access file systems or applications on the primary server through a virtual IP and are not cognizant of which server is actually the active primary server. The cluster management software provides for automatic server and application failover. Constant Replicator seamlessly integrates into the existing cluster manager through the Constant HA Cluster toolkit and provides a common data set across servers. Constant Replicator allows the customer to maintain a common data store between local servers Copyright 2004 Constant Data, Inc. Page 6 of 10

7 without the requirement of a SAN or servers located in different remote offices. 5.4 Long Distance Uni-Directional Replication of HA Clusters The simple uni-directional replication from an active source server to the virtual IP of a remote cluster allows enterprises to maintain an identical cluster of web servers providing off-site disaster recovery combined with high availability clustering. Constant Replicator enables companies to enhance existing tape backup solution with the addition of a remote server through the installation of an affordable server-based replication solution. An online mirror replica decreases downtime and increases data and application availability. Normal operation: Failover operation: 5.5 Bi-directional data replication between two servers on local area networks Constant Replicator bidirectionally mirrors data between two servers. By bi-directionally mirroring data between two servers, enterprises are able to maintain data consistency between the source and destination server. Constant Data s software solution allows data to be usable on both the master and remote/backup server with guaranteed data integrity. This enables enterprises to instantly switch between the source and the available destination server in the event of a business interruption. However, data consistency is maintained between the servers in much the same way as NFS: whichever server writes last wins. 5.6 Bi-directional data replication between multiple servers on local area networks Constant Replicator also bidirectionally mirrors data between multiple servers and can be used for content distribution. It distributes data by replicating among the participating sites. Information collected at one site is immediately available at all the other sites. Data is able to be accessed and updated on any server in the network. However, whichever server writes last wins. 5.7 Bi-directional data replication over long distances Constant Data s software solution bi-directionally mirrors data over high latency long haul networks between different locations. Enterprises are able to turn remote offices/sites into off-site data "bunkers" for Disaster Recovery and convert their network into a backup solution. Furthermore, enterprises are able to access and update data on any server in the mirror. Constant Data's bi-directional replication solution provides the remote offices with access to the same data, at each remote site, all the time. Not only is a fast disaster recovery guaranteed through bi-directional data replication, enterprises will have a more efficient Copyright 2004 Constant Data, Inc. Page 7 of 10

8 collaboration and workflow between the remote offices, because the data at each office is always in sync. 6.2 Storage Consolidation with an Integrated Failover Solution Constant Replicator bi-directionally mirrors data between servers located on wide area networks regardless of distance between servers. 6. Successful Solutions Constant Data real-time replication solution minimizes risk and improves business processes. Constant Replicator is flexible and versatile. It plays a critical role in safeguarding customer data when used for business continuance and disaster recovery. The real-time replication solution can be used to consolidate backups of build backup appliances or to automate content distribution. 6.1 Storage Consolidation Constant Replicator consolidates data between remote offices to a centralized data center enabling an organization to consolidate and store data. Its unique compression, encryption and bandwidth throttling allow replication to co-exist over existing networks. The real time software solution mirrors content automatically over low-bandwidth and high latency networks providing an affordable, scalable, simple and secure storage consolidation solution. Constant Replicator maintains a mirror of critical clusters of servers in the same way as individual servers. Companies increase the availability of data and application in remote offices by clustering an additional hot-standby server into the network. Data from the remote clusters is replicated as it changes to a central location where it can be backed up. In the event of a remote server failure, the server can be rebuilt at the main office and shipped to the remote location. 6.3 Content Distribution Constant Replicator is being used by customers to mirror critical data between data centers. This process reduces the operating cost and improves the efficiency of an organization by saving significant resources due to effectively managed data in central data centers and the consolidation of data and backups at one remote location. Consider a company providing data services from the main data centers in the U.S. to the main data center in Europe and to an alternate data center in the U.S. Business intelligence created during the hours of operation in each of these locations needs to be Copyright 2004 Constant Data, Inc. Page 8 of 10

9 propagated to the others. Using Constant Replicator, this organization makes data created at one of these locations available to the entire enterprise in the most efficient way possible. Constant Replicator ensures that only changed data is replicated, saving valuable network overhead. created in the West Replication Mesh are able to be retrieved from the East Replication Mesh and vice versa. At the same time, Constant Data s cross-platform technology reduced the company s IT costs by replacing a redundant in-house solution and freeing up employees to concentrate on the company s core business. Constant Replicator automatically updates all locations within the system right at the moment when changes occur. If an interruption occurs Constant Data s failover feature switches automatically to the remote location and allows the company to continue its business without any interference. 6.5 Universal Data Availability with Failover and Consolidation A variation of long distance replication clustering is the addition of real-time consolidation to a central server. In the following example, a customer is using Constant Replicator to distribute terabytes of multimedia in a telecommunications environment to remote data centers located across the country and guarantees the delivery of multimedia content. 6.4 Universal Data Availability with Failover Constant Replicator consolidates backups from a central location without impacting the production environment. 7. Conclusion Constant Data developed a fully connected and redundant replication mesh that assures that documents Constant Data offers a replication software solution that replicates only changed data from files and databases in real-time from one to one, one to many, many to one and many to many servers between different operating systems. The hybrid replication solution reduces the total cost of ownership by reducing system and configuration down time and by removing the required backup windows. Copyright 2004 Constant Data, Inc. Page 9 of 10

10 The reduction of business risk associated with system downtime translates into higher availability and a reduction in the cost of backup operations because less staff time is spent on backups. Constant Replicator can be used to consolidate data, automate data distribution or provide universal data availability. Constant Replicator offers increased levels of data availability without impacting a company s IT system performance. 8. Technical Highlights Constant Data s hybrid data replication solution has the following technology benefits: Assures delivery of data due to highly resilient replication technology Authorizes dynamic reconfiguration that allows addition of remote replicas with no system downtime Allows true cross platform replication (Solaris- Linux; Linux-Solaris; Solaris-AIX; Linux-Mac OSX, etc.) Maximizes available network bandwidth and performance through unique compression and fast byte-level replication Runs on any specified TCP/IP port over existing networks - firewall friendly Provides flexible modes of replication (1-1, 1-N; N- 1; M-N; uni-directional or symmetric) Guarantees data integrity through data journaling for resiliency over both local and unreliable wide area networks Automates the deployment, configuration and management through user-friendly graphical user interface (GUI), command line interface (CLI) tools and optional programmable API toolkit. 9. Full-Featured Product Evaluation A full-featured evaluation copy of Constant Replicator software is available for download from Constant Data at Copyright 2004 Constant Data, Inc. Page 10 of 10