Sun StorEdge™ Network Data Replicator 3.0 Configuration Guide Sun Microsystems, Inc. 901 San Antonio Road Palo Alto, CA 94303-4900 U.S.A. 650-960-1300 Part No. 806-7550-10 June 2001, Revision A Send comments about this document to: docfeedback@sun.
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Contents Preface 1. v Overview 1 Sun SNDR Software Description 1 Supported Hardware and Software 3 TCP/IP Connection Hardware Components Network Multipathing 2.
Configuring The Sun SNDR Software for Mutual Replication Order-Dependent Writes and Volume Set Grouping Recovery Considerations 12 13 14 Failing Over to the Secondary Site 14 Recovering the Primary or Secondary Site 14 Using The Sun SNDR and Sun StorEdge Instant Image Software Sun SNDR Software and Sun StorEdge Fast Write Cache Software One-to-Many and Multihop Volume Sets 18 Using The Sun SNDR Software in a Firewall Environment iv Sun StorEdge Network Data Replicator 3.
Preface The Sun StorEdge Network Data Replicator 3.0 Configuration Guide describes the Sun StorEdge™ Network Data Replicator (Sun SNDR) software and general information about its use. This guide is intended for system administrators who have experience with the Solaris™ operating environment and related disk storage systems.
Using UNIX Commands This document may not contain information on basic UNIX® commands and procedures such as shutting down the system, booting the system, and configuring devices. Refer to the software documentation that you received with your system. Documentation Conventions Typeface or Symbol vi Meaning Examples AaBbCc123 The names of commands, files, and directories; on-screen computer output. Edit your .login file. Use ls -a to list all files. % You have mail.
Shell Prompts Shell Prompt C shell machine_name% C shell superuser machine_name# Bourne shell and Korn shell $ Bourne shell and Korn shell superuser # Related Documentation Application Title Part Number man pages sndradm scmadm svadm iiadm N/A Latest information Sun StorEdge Network Data Replicator 3.0 Software Notes 806-7513 Sun StorEdge Instant Image 3.0 Release Notes 806-7678 Sun StorEdge Network Data Replicator 3.0 Installation Guide 806-7514 Sun StorEdge Instant Image 3.
Application System administration Configuration viii Title Part Number Platform Notes: The Sun Quad FastEthernet Device Driver 806-3989 Sun Enterprise 10000 InterDomain Networks User Guide 806-4131 Sun StorEdge Instant Image 3.0 System Administrator’s Guide 806-7677 Sun StorEdge Network Data Replicator 3.0 System Administrator’s Guide 806-7512 TCP/IP and Data Communications Administration Guide 805-4003 SunScreen 3.1 Administration Guide 806-4127 Solaris Bandwidth Manager 1.
Accessing Sun Documentation Online A broad selection of Sun system documentation is located at: http://www.sun.com/products-n-solutions/hardware/docs A complete set of Solaris documentation and many other titles are located at: http://docs.sun.com For the latest version of released storage software documentation, go to: http://www.sun.com/products-n-solutions/hardware/docs/Software/ Ordering Sun Documentation For the latest version of storage software documentation, go to: http://www.sun.
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CHAPTER 1 Overview Caution – Do not install or use the Sun StorEdge Version 3.0 Core and data services software on servers in a Sun Cluster 3.0 environment. The Version 3.0 software is not co-existent with the Sun Cluster 3.0 environment. The Version 3.0 software is co-existent in the Sun Cluster 2.2 environment, where it will not interfere with failover. The Version 3.0 core and data services software is cluster aware in the Sun Cluster 3.
The replication mode can be synchronous or asynchronous based as a user-selectable parameter for each Sun SNDR volume set. (Use the sndradm enable command and select the sync or async parameter Use the sndradm -R m command to change the replication mode thereafter.) The volumes can be updated synchronously in real time or asynchronously using a store-and-forward technique. Typically, a primary volume is first explicitly copied to a designated secondary volume to establish matching contents.
■ One-to-many and multihop volume sets — The Sun SNDR software enables you to create one-to-many and multihop volume sets. In a one-to-many volume set, you can replicate data from one primary volume to many secondary volumes residing on one or more hosts. In a multihop set, the secondary host volume of one volume set can be the primary host volume of another volume set. See “One-to-Many and Multihop Volume Sets” on page 18.
Network Multipathing Network multipathing with failover is supported on hosts running the Solaris 8, Update 3 operating environment. This feature is provided as part of the standard Solaris operating environment and is transparent to the Sun SNDR software. The Sun SNDR software does not natively support the functionality listed in TABLE 1 . However, other Sun products can be used with the Sun SNDR software to provide these facilities.
Applications The Sun SNDR software provides protection of critical enterprise information.
Primary host Application Sun STE or SV Sun SNDR NSCTL Network storage control module User User Sun STE or SV Kernel IP Kernel Sun SNDR Sun StorEdge Instant Image Sun StorEdge Instant Image SDBC SDBC Device driver Device driver Hardware Hardware FIGURE 1 6 Secondary host The Sun SNDR Software Architecture Sun StorEdge Network Data Replicator 3.
CHAPTER 2 Configuration Considerations Volumes Eligible for Replication Generally, include the following critical volumes in the Sun SNDR configuration: ■ Database and database management system (DBMS) logs (the total database or online DBMS log) ■ Access control files You can exclude volumes from the Sun SNDR software configuration if they can be reconstructed at the recovery site or if they seldom change: ■ Temporary volumes (such as those used in sort operations) ■ Spool files ■ Paging volume
Choosing Volume Level Protection In general, customers should protect their data with some level of RAID. With the Sun SNDR software, the primary volumes can be protected by any software or hardware RAID level desired. The protection level of the secondary volumes does not have to match that of the primary volumes. For example, if the primary volumes are RAID1, the secondary volumes could be RAID5. Bitmap Volumes for Scoreboard Logs Note – After editing the /usr/kernel/drv/rdc.
If your server is configured in a clustered environment, set the bitmap mode to 1. If your server is not configured in a clustered environment, you can also choose the bitmap mode setting of 1 to improve error or disaster recovery. Choosing a Connection Medium to Link My Sites The primary and secondary sites must be connected by a standard medium that supports TCP/IP. For example, you can use any medium such as ATM, ISDN, Ethernet, Gigabit-Ethernet, or T1 and T3 lines to replicate data.
Configuring Redundant Links Between Sites The Solaris 8 operating environment offers IP multipathing. This feature permits a Solaris host to group multiple physical network interfaces into a single logical interface. Redundancy between paths permits transparent operation in the event of a failure anywhere on the path including failures of network interface cards, links, switches and routers. This feature also provides the Sun SNDR software with the transparent means for surviving link failures.
Choosing Between Synchronous and Asynchronous Replication In synchronous mode, a write operation is not confirmed as complete until the remote volume has been updated. Generally, synchronous mirroring is limited to relatively short distances (that is, tens of kilometers) because of the detrimental effect of round-trip propagation delay on I/O response times.
When To Suspend Replication to the Secondary Site For many customers, the Sun SNDR software is used to mirror the primary site’s information onto the alternate location as quickly as possible under the constraints of distance and technology. Operator errors, software bugs, and hardware data corruption are solid arguments for taking more deliberate, albeit less real-time, approaches to remote copies.
Order-Dependent Writes and Volume Set Grouping For the Sun SNDR Version 2.0 software, write ordering is only maintained by the Sun SNDR software within a logical volume. In Version 3.0, write ordering is also maintained for groups of asynchronously replicating volume sets. (The general definition of write ordering here is that write operations directed to the target volume occur in the same order as write operations to the source.
Recovery Considerations The Sun StorEdge Network Data Replicator 3.0 System Administrator’s Guide contains information about various recovery scenarios.
Choosing the Resynchronization Type: Update or Full Tip – If a synchronization initiated by the sndradm -m or sndradm -m -r commands is interrupted, use the sndradm -m -u update command to complete the synchronization. Use /usr/opt/SUNWscm/sbin/scmadm -S to view the synchronization progress. An update resynchronization applies changes that occurred at the primary data to the secondary site during the time replication was suspended. The primary site can also be updated from the secondary, if desired.
Using The Sun SNDR and Sun StorEdge Instant Image Software To help ensure the highest level of data integrity on both sites during normal operations or during data recovery, use the Sun SNDR software with the Sun StorEdge Instant Image software. The Instant Image software is best used just before you perform a resynchronization, to help ensure that a consistent copy of data exists. In this case, if the resynchronization is interrupted, you at least have a copy of known good data that is usable.
Sun SNDR Software and Sun StorEdge Fast Write Cache Software Note – You cannot use the Sun StorEdge Fast Write Cache (FWC) product, including the SUNWnvm Version 3.0 software, in a Sun Cluster environment because cached data is inaccessible from other machines in a cluster. To compensate, you can use a caching array, such as the Sun StorEdge A3500 disk array. The Version 2.0 and Version 3.0 Sun StorEdge data services are binary incompatible. If your system includes Version 2.
One-to-Many and Multihop Volume Sets The Sun SNDR software enables you to create one-to-many and multihop volume sets. In a one-to-many volume set, you can replicate data from one primary volume to many secondary volumes residing on one or more hosts. One primary and each secondary host volume is a single volume set (each secondary volume requires its own unique secondary bitmap volume).
Using The Sun SNDR Software in a Firewall Environment You can use the Sun SNDR software with any enhanced network product that Sun offers. Port 121 must be available for use by the Sun SNDR sndrd daemon. You can use IP masquerading. SNDR uses connection-oriented service (COTS) based remote procedure calls (RPC; that is, TCP). The RPC part of the packet does not contain any address information.
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