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Snapshots for Rapid Recovery
“What are you doing for Rapid Recovery of Data?” If the answer to this question is “nothing” or “tape backup”, then read on. The explanation below may change the way you view data protection and rapid recovery!
Challenges: • Rapidly recover data in minutes – rather than hours – from file deletion, corruption and virus infection. • Overcome the limitations of traditional tape backup in protecting ever-growing amounts of data. • Deploy a solution that works with all storage arrays and all servers in the IT environment. Solution: • StoreAge multi View and multiMirror, to provide online rapid recovery and remote replication of data.Results: • Retain large numbers of low-capacity, disk-based snapshots for rapid online recovery without impacting performance of storage devices or servers. • Lower costs due to the use of a single product rather than multiple products to support various vendors. Snapshots for Rapid Recovery The number of IT applications that companies deploy is increasing every day. Productivity is increasing, but dependence on these applications is increasing as well. Today, most corporations are so dependant on these applications that their business cannot run without them – or the data they generate. IT managers are being tasked to protect unprecedented amounts of data and to recover from data losses in minutes, not hours or days. This cannot be achieved with traditional backup and recovery tools. To attempt to meet these difficult requirements, they are buying: • Disk-Based Backup Systems – All the tape library vendors are selling front-end disk systems that emulate their libraries. • Replication Software – Mirroring and replication software tools are used to create copies of data on separate arrays. • Snapshot Technology – One of the fastest growing trends is to use snapshots for creating instant, “live” backups of data for online rapid recovery. StoreAge multi View and multiMirror→→StoreAge’s multi View and multiMirror provide all the tools necessary to supplement tape backup, providing the ability to “backup” enormous amounts of data and allow rapid recovery from a variety of “disasters”. Each of these applications work with any SAN-attached storage array. This heterogeneous capability allows users to create a single set of data protection and recovery procedures that stay consistent regardless of the storage devices that users choose to deploy.→→ multi View –Because multiView can create thousands of space-efficient snapshots, it is a perfect tool for creating instant, point-in-time images that can provide much more granular “backup” than tape-based backup. Each snapshot is created in a few seconds, regardless of the volume size. This powerful snapshot tool can also create disk-based backups while applications are live, and offloads the data movement task from production servers.→→ multi Mirror – To protect from array failures or facility disasters, multiMirror can continuously replicate data to a low-cost array – locally, or to a remote facility.multi View vs. Array-based Snapshot
Most currently installed snapshot applications are array-based. The two key disadvantages to these solutions are that they are proprietary to the array that supports them, and that they are very limited in the number of snapshots that they can perform. Examples of these technologies are TimeFinder or SnapView (EMC), ShadowImage (HDS) and FlashCopy (IBM). Problems with Proprietary Implementations - All of the array-based snapshot offerings require the use of that vendor’s proprietary array hardware, and are licensed separately for each array. If you use storage arrays from multiple vendors, you will need to purchase and learn multiple snapshot packages from different vendors. Using multiple software products for the same purpose has several limitations. • Higher Initial Purchase Cost – Purchasing 3-4 different packages will cost more than one that supports all storage devices. • Administrators must learn multiple packages o Chance of errors increases substantially o Time required to learn and stay proficient with multiple packages is a waste of valuable resources • Lack of common policies and procedures – The use of multiple packages rarely allows interoperability and deployment of standards. Snapshot for Rapid Recovery – Historically, snapshots have been used to allow access to production data, while applications continue to run. Users could access a snapshot to perform a backup operation or use it to test new software while the main application program continues to operate. When the backup or the test was completed, the snapshot was erased. For these applications it was not necessary to do more than a few snapshots and if those snapshots consumed 1-2 times the storage capacity of the original volume, it was not a concern as the snapshot was deleted when the operation was complete. If users want to deploy snapshots to instantly protect data as a rapid recovery tool, the rules change. The concept is to take a snapshot of every volume once or twice a day for a week or more (10-15 active snaps per volume) and if data is lost due to something other than an array failure (less than 10% of data loss is from an array failure), the user mounts a previous snap to quickly recover lost data. This application requires the ability to create 1000’s of snapshots and each snap cannot consume much storage space or the associated costs will be prohibitive. Array Snapshots are Limited – Array snapshot applications require processing cycles from the array’s controllers. If multiple servers are requesting snapshots, the performance of the array is quickly degraded. Worse yet, all servers attached to the array will be affected – regardless of whether they are requesting a snapshot. Even the best arrays have a practical limit of 100-200 snapshots, with I/O performance degradation beginning much sooner. Another major flaw is that some of the array snapshot applications reserve space equal to at least 100% of the original volume’s size for each snapshot. These “full-sized” snapshots will severely limit the quantity and frequency of snapshot creation. →→multiView to the Rescue – multiView was designed as a network-based rapid recovery mechanism. It has the ability to create very low capacity snapshots and can maintain 1000’s of snapshots – perfect for a rapid recovery strategy. As a distributed network application, multiView is not limited to the resources of an individual device (array). Each host server does its own small amount of work to execute and maintain snapshots (through our host agent), and imposes absolutely no overhead on servers that are not performing snaps. Each snapshot consumes very little SAN storage, as multiView creates a very small temporary space where it directs all new writes to the volume. multiView then dynamically expands the size of the temporary volume in small increments, as needed. When the next snap is performed, the original temporary volume is frozen and another is created and all new writes are directed to the latest temporary volume. The result is that many snapshots can be performed without consuming large amounts of disk space. As an example, if a user performed two (2) snapshots per day for a week, and the data in that volume changed 10% per day, the amount of data consumed for those snapshots would be less than 100% of the original volume size. This is a small price to pay for 14 instantly recoverable disk images over an entire week. →→Data Consistency – multiView was designed with applications in mind. Snapshots are powerful, but without the ability to create consistent snapshots, databases and other applications would have out-of sync data. multiView supports “consistency groups” that allow snapshots to be created of multiple volumes at the same point-in-time, maintaining full synchronization of the datasets. →→multiView is Heterogeneous – multiView provides users with a single software package that works with all of their storage arrays. This heterogeneous capability not only reduces acquisition and support costs but also allows users to create a common recovery strategy regardless of the arrays they currently own or choose to purchase in the future. multi View vs. Disk-based BackupIn the last few years, disk prices have plummeted to the point where they can compete with tape on a cost per terabyte basis. This has led many users to consider using disk as a target for their backup applications, and all of the tape library vendors are selling disk systems that emulate their libraries. To the backup software, the disk drive looks like a tape drive and it sends the backup data to the disk in the same format it would to a tape drive. The main goal is to speed up the backup process and to improve recovery times. Users believe that disk drives are faster than tape drives, and therefore should be able to accomplish these tasks faster. The reality is that disk transfer rates are not any faster than today’s highspeed tape drives. Some tape emulation disk systems can create faster data streams through the use of proprietary file systems. However performance is limited by the number of streams available. Using more tape drives can offset this advantage. While disk has the advantage of random access capability, it has no clear advantage in the speed with which it can backup data. In recovery mode, these disk subsystems eliminate tape mount times and reduce seek times to file marks for individual files. However, to recover disk volumes or restore applications, all data must be sequentially transferred to a new disk system to be useable. Overall, the backup speed and recovery improvements are relatively nominal. The Real Problem – The massive growth in the amount of data that users must protect and their dependency on the applications that use it have created real problems. →→ Too Much Data – Users cannot physically move data from one device to another fast enough to “back up” the massive amounts of data they must protect. While a terabyte per hour backup speed is considered fantastic, how do you backup 20, 50 or 100TB of data in a short period of time? →→ Restoring Critical Applications – How do users get their database applications back on-line after a data corruption event or a virus attack? Moving terabytes of data that is in tape format from disk or tape back to your production storage system will take hours or even days. →→ Restoring Critical Data – Backups are usually done once per day. With massive amounts of data to protect, even daily backups are often not completed. In the event of a failure, any data created since the last backup will be lost. Losing an entire day’s worth of data is not acceptable to most businesses. →→multiView to the rescue – again! – When multiView creates a snapshot, it creates a point-in-time (PIT) instant disk image. When you want to use the data, the snapshot functions exactly like the original volume at the point-in-time that it was created. Unlike a backup volume that is in tape format, a multiView snapshot is instantly available just like the original volume. →→Let’s see how multiView solves the problems we outlined. • Too Much Data – Unlike traditional backup operations, multiView doesn’t need to move the data anywhere. Since it takes only a few seconds to create a snapshot of a volume, regardless of its size, multiple-terabyte per minute data protection is possible with multiView. Problem solved! • Restoring Critical Applications – Again, unlike restoring backup data from tape or disk, multiView does not need to move the data anywhere. Restoring an application’s data from a snapshot is immediate. Simply mount the snapshot to the application server and you are back online. Problem solved! • Restoring Critical Data – Because multiView snapshots are instant and low-capacity, users can take frequent snapshots throughout the day (e.g., two or three times per day). With more frequent snapshots, the potential data loss since the last snapshot is far less than it would be to go back to the last tape (or disk) backup. Problem solved! Combining multiView with multiMirror Recent studies indicate that well over 90% of the incidents that cause data loss, involve something other than a disk array failure. In other words, multi View offers sufficient protection of your data over 90% of the time. To protect against the remaining 10% (e.g., an array failure), data will need to be copied to an alternate array. Traditional backup to tape or to disk solves the problem of moving the data to another device, but cannot restore data and applications quickly. Mirroring software from the array vendors allows you to mirror the data to another array, but usually requires each array to be identical, making this type of protection very expensive.→→multi Mirror allows you to mirror your data between arrays from any vendor, including low-cost arrays. This mirroring can be done locally or to a remote facility. See the “What’s Hot” document on Mirroring for more details. By combining multiView to create snapshots and multiMirror to mirror data locally or to a remote location, users have total data protection. If files are accidentally deleted or corrupted, or a virus attacks, data is protected through multiView snapshots. If an array fails, a local mirror provides the recovery path.If data center is out of service, a remote mirror has protected the data – Total Data Protection.
multi View Rapid Recovery Snapshots• Each snapshot is a fraction of the size of the original volume • 1000’s of snapshots are possible • Snapshots are created in seconds without the need to move data • Each snapshot is a fully usable copy of a volume • Fast recovery of data (minutes) • Fast recovery of applications • Protects user against any non-array failure • multi View works with any storage arraymulti Mirror completes the data protection• Create a local mirror to a low-cost array • Create a remote mirror over low cost communication lines to low-cost arrays • multi Mirror works with any storage array
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