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Datalink oracle backup_recovery_white_paper


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Datalink oracle backup_recovery_white_paper

  1. 1. w h i t e pap e rEnterprise Backup and RecoveryMethodologies for OracleBy Data l i n k Abstract Organizations house some of their most business critical paper provides an introductory overview of some of information in Oracle® databases, making it imperative the enterprise backup options available for Oracle to have sound backup and recovery processes in place environments. It is aimed at IT professionals—including to protect this data. Backing up and recovering Oracle database administrators, storage administrators and environments can present unique challenges. A variety of managers—and anyone who plays a role in architecting technologies are available that—if used correctly—can and implementing the backup and restore processes of assist companies in overcoming these challenges. This Oracle systems. March 2009 | Page 1
  2. 2. Table of Contents Abstract 1 Introduction 3 Database data is extremely valuable 3 Backup options for Oracle 3 Various alternatives are available 3 Deploying the right solution 3 Need to weigh several factors 3 Backup in an Oracle environment 4 Systems are complex 4 Unique challenges 4 Ensuring data consistency 4 Backing up in the correct order 5 The landscape of RPO and RTO 5 Oracle backup methods 6 Oracle hot backup mode 6 Oracle RMAN 6 Oracle Data Guard 6 Oracle Export Import Utilities 7 Oracle Data Pump 7 Oracle Flashback 8 Storage-based backup methods for Oracle environments 9 ‘Undiscovered’ technologies 9 Triple mirroring 9 Array-based replication 9 Snapshots 9 Other backup enhancements 11 Enterprise backup scheduling software 11 Deduplication 11 Encryption 11 Summary 13 Backup for Oracle environment requires careful analysis 13 Datalink can help 13 March 2009 | Page 2
  3. 3. Introduction Introduction Database data is extremely valuable Oracle databases generally host mission critical data requirements demand that organizations be able to for business operations. This content is often revenue recover database environments in both a timely manner generating, driven by business applications that span and without corrupting or losing more data than the the enterprise and support a wide variety of activities company can withstand to lose. Data loss or the inability performed by an organization’s customers, employees and to quickly recover data could cause severe financial other stakeholders. These activities can range from online repercussions for a company and its customers and e-commerce purchases to deposits in a savings account or partners. This white paper examines some of the available the tracking of global inventory and shipping. options and considerations for backing up and recovering Oracle database environments. While it is important for companies to have a solid enterprise backup plan in place for all corporate There are a myriad of enterprise backup and recovery solutions on the market for Oracle- information assets, the requirements are especially based environments. stringent for database applications and data. Business Backup options for Oracle Various alternatives are available There are a myriad of enterprise backup and recovery These include triple mirroring, array-based replication, solutions on the market for Oracle-based environments. and snapshots. Oracle Corporation provides several native options such Beyond this, several hardware and software manufacturers as hot backups, Recovery Manager (RMAN), Data Guard, provide technologies that can be integrated within Export/Import, Data Pump, and Oracle Flashback. backup solutions to help monitor and manage the backup Storage vendors such as NetApp, Hitachi Data Systems environment. Also, other products can enhance backup and EMC offer a variety of solutions that can further performance, security, and fulfillment of compliance enhance the Oracle backup and recovery process and, in requirements of Oracle data through features such as some cases, address limitations of Oracle-only solutions. deduplication and encryption. Deploying the right solution Need to weigh several factors The type of backup and recovery solution that an data a company can lose and how frequently the data organization deploys for its Oracle environment should be must be captured in the backup system. For instance, some driven by recovery point objectives (RPOs) and recovery organizations may decide that they can withstand to lose an time objectives (RTOs). The RPO describes how much hour’s worth of transactions or even a day of transactions. continued on next page March 2009 | Page 3
  4. 4. Backup in an Oracle Environment Need to weigh several factors (continued) Meanwhile, other organizations, such as financial institutions, data from an application where the data is refreshed every might determine that they cannot afford to lose any data. evening or where the data could be completely re-created For them it is well worth the extra cost and effort required from another source. to deploy a solution that captures every transaction and As an organization defines its RPOs and RTOs, there must ensures no records are ever lost. be buy-in from upper management so that company-wide RTO describes how long applications or parts of standards can be established. Ideally, management sets the applications can be down while the IT area is recovering or business objectives and the IT department can then scope failing over data. In determining RTO, organizations should out the cost and effort involved to meet these objectives. ask questions such as, “How long could our business wait to There is a wide range of solutions, each of which meets recover a specific table?” or “How long could our business varying business requirements and has a different cost wait to recover the entire data center?” associated. It is important to note that the stringency of the RPO and RTO requirements and the cost of the backup Organizations should define RPO and RTO on an and recovery solution to meet these requirements are, for application by application basis. For example, when defining the most part, directly proportional. The good news is that RTO, recovering the database for the payroll application there are now hardware and software technologies available may not be as time sensitive as recovering the database that make these solutions much more cost effective. that services an e-commerce application. Or, as it relates to RPO, companies likely will not be able to afford losing When backing up an Oracle environment, any information from applications that generate credit card there are some unique challenges that present transactions. Meanwhile, they may be able to lose some themselves Backup in aN Oracle environment Systems are complex When backing up an Oracle environment, unique hand, comprise a complex system of interrelated files. challenges present themselves. In the “non-Oracle” They cannot be backed up in isolation, but rather must be world, flat files such as Microsoft Word® documents or backed up in sets and in the correct order. The challenges executables can generally be backed up and recovered on in doing this span several fronts. an individual basis. Oracle databases, on the other Unique challenges Ensuring data consistency First, it can be difficult to know which sets of files to back It is essential to know which files are interrelated so that up and recover in consistent groups. For instance, multiple the proper sets of files can be grouped together in a databases and applications often talk to one another. backup. Otherwise, it may not be possible to restore continued on next page March 2009 | Page 4
  5. 5. The Landscape of RPO and RTO Ensuring data consistency (continued) the system to a consistent state. A simple illustration of this a product. Depending on how the system is architected, would be a bank customer transferring funds from Account the order information could potentially be housed in two “A” to Account “B.” The sets of files that contain information different databases (one where the order is placed and about the deposit transaction and withdrawal transaction one where the order is fulfilled). If there is an outage and may be located in different areas, but they are interrelated. the databases are not restored to consistent states, then The bank would need to ensure that both of these files sets one database might show the order while the other might were contained in the same backup. Otherwise, if the system not. Data consistency is extremely relevant if an application crashed and was subsequently restored, it may only reflect relies on multiple databases or if data is distributed the withdrawal to one account and not the deposit to the through Oracle snapshots, Oracle Streams, Oracle multi- other (or vice versa). master replication, or application-level replication. These replication technologies are common in business Ensuring data consistency across multiple databases and applications can be challenging, but it’s extremely important. applications such as Oracle e-Business Suite, SAP®, Oracle’s Another example of this is a customer placing an order for Siebel CRM, PeopleSoft, and home-grown applications. Backing up in the correct order It’s also important in an Oracle environment to back up Only by understanding each of the available options for files in the correct order. When files are not backed up backup and recovery and the strengths and weaknesses in the correct order, it’s easy to inadvertently overwrite a of each can an organization ensure a proper enterprise control file, which is a set of pointers that indicates where backup environment. Even then, the data protection various files are located and which files they’re associated strategy must be properly executed and periodically with. This then becomes an issue if the organization needs tested in order to serve the needs of the business. to recover the database to a particular point in time. Without the control files, the organization cannot recover Ensuring consistency across multiple databases the database to a certain point in time and will lose data. and applications can be challenging, but it’s extremely important. Unfortunately, this is not an uncommon occurrence. The landscape of RPO and RTO Recovery Point Recovery Time days hours seconds seconds hours days $ Cost of Protection $$$ $$$ Cost of Recovery $ Failure $$$ Cost of Lost Data $ Occurs $ Cost of Time $$$ Tape Backup Async Replication Syncronous Replication Snapshots Copy-on-write Tape Backup Hot Backup RMAN Data Guard Snapshots Hot Backup RMAN Data Guard The ability to meet RPOs and RTOs varies depending on the solution type as outlined above. March 2009 | Page 5
  6. 6. Oracle Backup Methods Oracle backup methods Oracle offers several options for backup and recovery that are native to the software. Depending on which version of Oracle an organization has, these options may vary. Some benefits and drawbacks of the various Oracle backup methods are listed below .Oracle hot backup mode Oracle’s hot backup mode enables physically copying files to CONS: The process of backing up and recovering entire file another disk or tape while the database is active. systems can be prohibitively lengthy and a challenge for RTO. Recovering a 500Gb database alone can take several hours and PROS: This method provides recovery without any data loss and recovery of a multi-terabyte environment can take this amount of can be used with other backup methods as well. For example, time many times over. System performance degrades during the performing nightly hot backups enables a company to recover a backup process (10-15 percent on standard systems). Additionally, database to the previous night, then applying all redo log changes this method only backs up the database itself and not customized (provided these logs were online or mirrored or copied to another code or non-Oracle systems such as Exchange or SQL. And, if online system) brings the database back to a consistent point in time, with and archived redo logs are not mirrored or copied to another a strong RPO. Most database administrators are likely familiar with system, data may be lost in the event of a recovery. this method. Oracle RMAN Oracle’s RMAN software copies only database blocks that have other Oracle and third-party solutions to provide additional changed since the previous backup. This significantly improves capabilities, such as deduplication and encryption. backup and recovery times over copying full files with hot or cold CONS: RMAN only backs up the database, not non-Oracle systems backup methods. In fact, many companies see a 10x improvement such as custom applications, executables or scripts. As with the RPO (or more) for both backup and recovery, depending on the amount of hot backups, if redo logs are not mirrored or copied to another of updates that were made between backups. system, the result may be lost data in the event of a recovery. PROS: RMAN enables a company to significantly reduce its RTO. For example, a 30-hour backup of two terabytes might only take Depending on the application, the logical version three hours using RMAN. In addition, because only changed data is of Data Guard can provide huge improvements in backed up, the backups will require less storage space. This method RTO and replication performance. also backs up in parallel streams/channels. RMAN works well with March 2009 | Page 6
  7. 7. Oracle Backup Methods Oracle Data Guard Oracle’s Data Guard replicates Oracle databases from one data alternate database is already up and running and in sync with the center to another. It also enables companies to perform backups primary database, data recovery is just a matter of switching over to from the Data Guard’s standby database instead of the production the alternate site while running in synchronous mode. database, improving production performance during the backup Data Guard works well in conjunction with array-based replication, window. Data Guard can be used in either a standard physical or but there are bandwidth and physical site distance latency issues logical version. The physical version applies the changes from the with replication if the volume of transactions is significant. Oracle redo logs to the destination target. The logical version meanwhile sends one SQL statement at a time to change the records CONS: Data Guard’s most robust features are only supported in at the destination target. the Oracle 10g and 11g releases, so it may not provide the required functionality in Oracle 9i or earlier environments. Data Guard only PROS: Depending on the application, the logical version of Data supports Oracle databases (and even then not application and Guard can provide huge improvements in RTO and replication database source code). If running in asynchronous mode, there performance. With the logical standby architecture, one SQL could be data loss during a failure, hurting the RPO. And data will command can instruct the system to change millions of records not be replicated if a table or loading process is in NOLOGGING (versus sending a million record changes in a database block). This mode. Additionally, organizations may need to purchase a license can also significantly reduce bandwidth. Additionally, with the for the standby database. The standby database must also be logical version it’s not necessary to have identical structures at the running in order for changes to be applied, which impacts the primary and secondary sites (as is with the physical version). This performance of any other applications running there. makes it possible to use less expensive disk as the replication target. The logical version is most effective in environments where SQL Many third party hardware and software-based statements are used to update large amounts of data at once. backup and recovery technologies can be Using Data Guard’s synchronous mode (in the physical version) also applied to Oracle data to improve backup and recovery performance. enables quick RTO with an RPO of no data loss. Because the Oracle Export Import Utilities Oracle’s Export/Import utilities generate logical backups of tables. CONS: The backup and recovery process with this method is fairly That is, rather than copying the physical blocks of data, the utilities lengthy. A recovery of just a few hundred gigabyte table can take copy the series of commands used to recreate the tables. several hours to perform. RPO is also an issue as this solution does not provide the ability to recover past the point at which the export PROS: Export/Import offers the ability to recover on a table-by- started. Consequently, this method is not very feasible for tables table basis. So if only one table is needed, the backup administrator that change. can selectively import that table versus recovering, for example, a 2 TB database. March 2009 | Page 7
  8. 8. Oracle Backup Methods Oracle Data Pump Oracle’s Data Pump provides much of the same functionality as storage. Or, perhaps the backup is impacting performance and the Export/Import and offers several new features as well. organization wants to resume it during off-peak hours. PROS: Like the Export/Import utilities, this method enables recovery CONS: Like the Export/Import utilities, RPO is an issue as it is not on a table-by-table basis. It also uses multiple parallel streams for possible to recover past the point in time that the Pump process faster performance. In addition, it provides the ability to suspend started. As for RTO, even though Data Pump is typically 15-45 times and restart data transfer. That way, organizations can pause backups faster than Export/Import, it still can take a long time to back up and and restart them at their convenience (without having to start over). recover compared to snapshot methods (hours versus minutes or This might be necessary if an organization needs to add additional seconds). Oracle Flashback Oracle Flashback Area allows for recovering a table (or database) to CONS: Flashback requires a significant amount of Flashback Area any point in time in the past by storing images of data online. online, taking up lots of storage. Also, the database must be up and active to connect to the Flashback Recovery Area. Although some PROS: This method provides online backup and recovery, functionality was introduced in Oracle 9i, the more robust features eliminating the need to recover from tape and saving valuable only work with Oracle 10g. While Oracle’s Flashback capabilities recovery time and management effort. It provides a great improve RTO, backups of the database must still occur for meeting improvement in RTO through extremely fast recovery of tables with RPO and avoiding lost data. simple SQL commands. Array-based replication solutions fill in the gaps of Data Guard by replicating non-Oracle systems and source code as well as tables in NOLOGGING mode. March 2009 | Page 8
  9. 9. Storage-based Backup Methods for Oracle Environments Storage-based backup methods for Oracle environments ‘Undiscovered’ technologies Many third party hardware and software-based backup be deployed within the backup architecture for non- and recovery technologies can be applied to Oracle data Oracle applications and files; however, the database to improve backup and recovery performance. These staff may be unaware of how the technology is being technologies are independent of Oracle and typically are used or its benefits to the database environment. When also integrated in the backup of non-Oracle applications architected properly, these solutions can prove extremely and files. These solutions are sometimes “undiscovered” in valuable and meet some needs that simply cannot be met the world of database administrators. They may already with Oracle-only technology. Triple mirroring Triple mirroring is a backup strategy where the eliminating performance hits of being in hot backup mode organization copies the data in real time to three sets of for extended periods of time. redundant disks. One of those three sets is broken off CONS: It can be expensive to keep a set of production- when the database is in hot backup mode and the data is sized disks. Companies still may not be able to meet then backed up at a more leisurely pace from the mirror backup windows, especially if backing up from the mirror slices. The other two redundant data sets remain in use for takes more than 24 hours. Because of the amount of disk production. Once the backup is complete, the third mirror involved, it is not feasible to maintain multiple recovery is synced back up with the primary copies. points for the data. PROS: It’s possible to split the mirror almost instantaneously and back up from the slices, thereby Array-based replication Like its name implies, array-based replication offers replication traffic and reducing or eliminating single points replication between two storage arrays—in most cases the of failure. Regardless of whether or not it’s used with Data devices must be from the same manufacturer. This method Guard, array-based replication will significantly improve sends storage layer blocks to a standby site whenever RTO and RPO. there is a storage change at the primary site. CONS: There is a cost associated with purchasing and PROS: Array-based replication solutions fill in the gaps of maintaining a third-party array-based replication solution. Data Guard by replicating non-Oracle systems and source An ROI analysis may demonstrate that this cost can be code as well as tables in NOLOGGING mode. This works justified. The point at which it is recouped will depend on best in conjunction with Data Guard by jointly reducing the value of the data. March 2009 | Page 9
  10. 10. Storage-based Backup Methods for Oracle Environments Snapshots Snapshots, often referred to as point-in-time copies, can be taken every 15 minutes, requiring no more than allow near instant backup and recovery of large data 15 minutes of redo log applies. Some third-party vendors sets using a sophisticated, scalable, and fail-safe pointer also have management software for scheduling and system of storage blocks. Snapshots represent a read-only integrating with Oracle RMAN. view of data taken at a specific point in time. Data and CONS: There is a cost associated with purchasing third- entire environments can be restored to a known stable party snapshot-based storage products. As with the other point prior to the event that caused the disruption or storage-based methods, an ROI analysis will demonstrate corruption. that this cost can be justified. The point at which it is PROS: Online backup and recovery is fast and seamless recouped will depend on the value of the data and the and eliminates the need to recover from tape. It is possible value of the speed of backup or recovery. Also, some to recover a 4 TB database in minutes and keep hundreds vendors use copy-on-write technology for snapshots of snapshots (and therefore hundreds of recovery points) which may degrade performance of the primary disk online. RTO improves with the number of snapshots a system during snapshot activity. This can be addressed vendor can manage. This is because database recovery with some vendors providing “zero performance impact” occurs in two phases: first the image recovery of the snapshots. database and then application of the redo log changes. If a storage vendor can only provide a handful of snapshots, Additional solutions that monitor and manage then typically 12 to 24 hours of redo logs must be applied backup and recovery processes include before fully recovering the database. If a storage vendor enterprise scheduling software. can offer dozens or hundreds of snapshots, then snapshots March 2009 | Page 10
  11. 11. Other Backup Enhancements Enterprise backup scheduling software Additional solutions that monitor and manage backup and risks and simplify the management of complex and recovery processes include enterprise scheduling software heterogeneous environments that often have dozens or such as IBM Tivoli,® HP OpenView, CA Unicenter,® and even hundreds of applications. BMC® Patrol.® These solutions help schedule and monitor Also of note are GUI solutions from leading storage the end-to-end process of backing up and recovering an manufacturers that integrate and schedule snapshot enterprise—from the applications to the databases and technology with backup environments, integrating with the rest of the enterprise storage data. By using these Oracle’s RMAN, ASM, RAC, and more. solutions, companies can reduce backup and recovery Deduplication Deduplication through third-party solutions can channels. Deduplication can be applied to data at rest dramatically reduce the backup stream size—typically in the storage layer, within the database (Oracle 11g 10-20 times—and bandwidth required for backup. compression), through virtual tape libraries (VTLs), or Deduplication works by detecting redundant data across a network. In practice, deduplication can reduce patterns during the backup process and saving references the amount of physical disk storage required for backup to that data (versus actual streams of blocks of data) when and recovery by factors ranging from 10:1 to 30:1, or even duplicate streams are detected. When set up properly, greater for sparse environments or environments that deduplication can work well with multiple Oracle RMAN change infrequently. Encryption Companies often store unencrypted yet sensitive data management is an important consideration. on tape. This opens up the company to vulnerabilities— Methods for encryption include: whether it’s somebody stealing the tape or the tape being 1) racle secure backup–Using Oracle’s Secure Backup O lost in the warehouse or while being transported off-site. method, organizations can encrypt Oracle’s RMAN Encrypting sensitive data or the entire backup can quickly backups before they are written to tape. Oracle also and easily solve this issue. Beyond this, encryption of has capabilities for storing data encrypted within the backups may even be a corporate or government mandate database and, thus, also encrypted on tape. for an organization to meet its compliance requirements. Options for encrypting data exist within Oracle and with y encrypting at the database level, an organization B third party providers as well. It is worthy to note that with reduces much of its exposure. This method is also free any type of encryption strategy, encryption key (for one direct-attached storage device). A downside continued on next page March 2009 | Page 11
  12. 12. Other Backup Enhancements Encryption (continued) o this type of encryption is that there are no auto- t single points-of-failure for key loss. By using a hardware destruct or multi-master key management features. and software appliance, backup streams can be encrypted Typically, the DBA is solely responsible for retaining with negligible impact on performance. the key and there are inherent weaknesses with this strategy. 2) hird-party encryption–Third-party vendors provide T encryption at the storage level. Many of these solutions provide multi-master key management that prevents March 2009 | Page 12
  13. 13. Summary summary Backup for Oracle environment requires careful analysis Many companies use combinations of Oracle-based and management complexity—before implementing a solution. third party solutions for better protection and improved Because of the complexities involved in developing a well- performance of their mission critical Oracle data. Because designed backup and recovery architecture for an Oracle criticality and the interrelated nature of the data will vary, environment, it is often helpful to work with a company there is no “one size fits all” solution. Organizations should that is knowledgeable about the alternatives available and consider several factors—including RPO and RTO of the that has experience in weighing the various benefits and individual applications, total cost of ownership (TCO), and drawbacks of each. Datalink can help A complete data center solutions and services provider their information assets, which include a combination of for Fortune 500 and mid-tier enterprises, Datalink Oracle and non-Oracle data. Our independence allows transforms data centers so they become more efficient, us to recommend hardware and software technologies manageable and responsive to changing business needs. that provide the most optimal fit for an organization’s Datalink helps leverage and protect storage, server, and environment and enable them to effectively meet their network investments with a focus on long-term value, business initiatives. Datalink has extensive field experience offering a full lifecycle of services, from consulting and with a wide range of technologies. This, combined with design to implementation, management and support. the knowledge we glean from in-depth testing conducted Datalink solutions span virtualization and consolidation, in our interoperability labs, provides us with invaluable data storage and protection, advanced networks, and insight that we can pass on to our clients as we design and business continuity. Each delivers measurable performance implement data center solutions. gains and maximizes the business value of IT. For several years, Datalink has worked with organizations For more information, contact Datalink at to help define and implement strategic solutions for (800) 448-6314 or visit March 2009 | Page 13