Choosing the Right Deduplication Solution for Your Organization Application-based deduplication versus appliance-based deduplication Introduction Due to the significant data growth and extended retention requirements organizations face today, almost every backup and recovery solution on the market now includes deduplication and compression capabilities. Together, deduplication and compression enable impressive savings, including reduced storage and network requirements, lower power and cooling loads, better recovery point objectives (RPOs) and recovery time objectives (RTOs), and shorter backup windows. Also, precious data center storage real estate becomes ~15 times more scalable, and organizations can effectively protect data generated at remote and branch offices by replicating deduplicated data to central locations using existing and often limited bandwidth. There are two popular approaches to implementing compression and deduplication capabilities in backup environments: Using deduplication and compression functionality that is integrated into backup software applications Using the deduplication and compression features of purposebuilt back-up-to-disk appliances (PBBAs) In most cases, there is no benefit to implementing more than one deduplication approach. But which of the two approaches is better for your organization? One might think that the first option would offer more benefits, since tight integration often offers efficiencies through use of shared technologies. In practice, however, choosing the right option is more complicated, because deduplication technology can have profound effects on multiple areas of the backup environment. This white paper explores the key areas of impact to help you make an informed decision about the best deduplication solution for your organization.
A common frustration with backup and recovery solutions is logjams at the media server. The two approaches to deduplication Let s begin with a quick overview of the two approaches to implementing deduplication: technologies are fast, scalable and extremely efficient. As backup data sets grow over time, the appliance s superior deduplication algorithms scale to extremely large data stores with millions of files. technology is less efficient and more limited. For example, many of these offerings implement a fixed block approach for deduplication, whereas appliances implement variable block size deduplication technology. Additionally, many software solutions are limited to smaller deduplication stores. When multiple deduplication stores are required, deduplication becomes less effective and savings diminish because deduplication does not span across deduplication stores. A complete picture of each option, though, extends far beyond these direct benefits and drawbacks. The rest of this paper explores how these deduplication technologies affect the broader backup environment, including resource contention, costs, flexibility, maintenance and risk. The media server A common frustration with backup and recovery solutions is logjams at the media server. As backup demands grow over time, the media server can become overtaxed by lack of resources, encounter networking issues when sending data to or receiving data from the protected client, or a combination of both. In particular, running multiple backup and restore tasks together in parallel can cause media server logjams to quickly appear. In fact, when a backup softwarebased deduplication approach is chosen, media server workloads are increased tenfold. This is because the media servers are additionally taxed with ingest deduplication (hashing), management of the deduplication dictionary database, rehydration of data to tape and replication workloads. In addition, client-based deduplication workloads may also be introduced on the media server. With software-based deduplication, the media server workload includes all of the following: Processing client backup data Ingest deduplication (hashing) Managing the deduplication dictionary Creating tape copies from disk Rehydration processing Replication Figure 1. increases the media server workload significantly. 2
Client 1 Client 2 Client 3 Client 100 Media server 1 Media server 3 Media server 5 Media server 2 Media server 4 Media server 6 Figure 2. With software-based deduplication, avoiding logjams requires adding more media servers, which increases costs and complexity. To avoid logjams, customers often add media servers equipped with greater CPU and memory resources (see Figure 2). While this approach spreads out the extra load, it also obviously increases complexity and costs. Because purpose-built backup to disk appliances absorb deduplication and replication workloads, current backup environments can remain unchanged. Complexity is avoided because there is no need to beef up the number and horsepower of media servers (see Figure 4). SAN or local storage 10 / 15K Purpose-built backup to disk appliances absorb deduplication and replication workloads, so the media server workload is limited to: Processing client backup data Creating tape copies from disk Figure 3. Appliance-based deduplication puts no extra load on the media server. With appliance-based deduplication, there is no need to beef up the number and horsepower of media servers. 3
Client 1 Client 2 Client 3 Client 100 Media server 1 Media server 2 Media server 3 Purpose-built deduplication appliances are built to simultaneously handle deduplication loads across multiple backup applications. Purpose-built backup-to-disk appliance Figure 4. does not put additional load on media servers. What if the backup environment is already equipped with bigger and faster media servers with no logjams? Does this diminish the value of appliancebased deduplication? Definitely not. In fact, if desired, purpose-built backup to disk appliances can offload the deduplication processing from the appliance to a number of media servers. If enough media server resources become engaged, the deduplication process for backups can become faster than the appliance itself. Costs Vendors of backup software deduplication and compression solutions tout significant costs savings when compared to dedicated appliances, pointing out that existing investments in SAN, NAS and DAS storage systems can be utilized to support backup storage needs. However, these vendors fail to include in their calculations the tenfold increase in media server workloads with software deduplication solutions and the resulting significant cost of spreading this additional workload across a greater number of media servers with big CPUs and memory to avoid logjams. In addition, meeting service level agreements (SLAs) often requires fast and therefore expensive solid state disk (SSD) drives be used for target repositories. These costs wash out the touted backup software deduplication and compression savings. Flexibility Each backup software application implements a proprietary approach to deduplication and compression. Thus, if an environment uses multiple backup software applications, two or more software-specific deduplication technologies are being implemented, which can make the environment more complex and difficult to manage. On the other hand, purpose-built deduplication appliances are not anchored to any specific backup software product they are built to simultaneously handle deduplication loads across multiple backup applications. This capability is extremely valuable to IT environments that use multiple backup products. Moreover, as updates or changes to backup software occur in the future, the deduplication appliance can continue to be used, maximizing the value of the investment. 4
Management and maintenance With purpose-built backup appliances, storage administration expertise is unnecessary because use of virtual storage entities abstracts management tasks such as creating LUNs, configuring RAID groups and mounting volumes. Appliance dictionary databases and all other components are pre-configured, making the appliance immediately ready for operation after a short deployment wizard is completed. Management is simple as well. The internal storage system is equipped with cost-effective, high-capacity hard drives, offering significantly denser target repositories for backup workloads than storage with software-based solutions. When appliances require additional storage, an expansion is quick and typically non-disruptive. Appliances will immediately begin to use the extra capacity without any need to tune LUNs or RAID groups or perform any other storage-related tasks. Deployment and management are not as simple for software-based deduplication solutions. CPU, memory and storage must be properly sized for each media server and because there are more servers, there is more to scope and manage. To ensure adequate performance, fast and expensive solid state disk drives dedicated to the deduplication database must be properly sized and configured into LUNS, RAID groups and so on, following vendor or company best practices or configuration guidelines which typically requires assistance from a storage specialist. Over time, deduplicated data will continue to grow. When maximum storage capacities are reached, a storage specialist will be required again to reconfigure disks and RAID groups and perform other storage-related tasks. Tolerance solutions piggyback the backup environment s media servers, which typically run well-known, full-blown operating systems. These operating systems are easy targets for viruses, worms and other malware so components such as the deduplication database are likely to experience unexpected hiccups and even outages, putting the organization at risk of data loss. And when corruption occurs, restoring the deduplication database is time-consuming. An appliance-based deduplication database is significantly less susceptible to corruption because its components run within a controlled, locked down operating environment. Every driver, service and component is well understood, and they are designed to work closely together as a complete solution, making it significantly more difficult for outside influences to cause corruption and also making the database significantly easier to recover. Rehydration In disk-to-disk-to-tape (D2D2T) backup environments, backups that are deduplicated and compressed on a disk are rehydrated to their native format and preserved on tape for longer term retention. Rehydration is a very long and resource-intensive task because unique deduplicated chunks of data are stitched back together to form the original backup. Because of this, backup softwarebased duplication solutions can be difficult to size for. While processing deduplication for backups, the media server will also be processing the rehydration of data, which can typically run 24x7. When aggressive recovery time objectives are required, beefing up the media server resources to meet these time windows can be quite costly. An appliance-based deduplication database is significantly less susceptible to corruption because its components run within a controlled, locked down operating environment. 5
Purpose-built deduplication and compression appliances offer an affordable, powerful and easy-to-use solution that can scale to handle growing data sets without rip-andreplace. Purpose-built backup appliances, on the other hand, absorb all rehydration workloads from D2D2T environment components, which make them much easier to size for. Conclusion Data sets and regulations are both growing rapidly, but IT staff size is not. Therefore, today s IT solutions must be simple to deploy and use, and must be able to scale to meet aggressive data growth. Deduplication and compression are first-rate technologies to manage growing data sets that require longer and longer retentions. When choosing deduplication technology, organization cannot afford to ignore the impact to their broader backup environments. Softwarebased deduplication solutions claim to be more cost-effective than their appliance-based counterparts, but these alleged savings disappear when you factor in the hidden costs of adding media servers with powerful CPUs and lots of memory, upgrading to expensive SSDs, hiring storage management expertise, and risking downtime and data loss. Moreover, purpose-built deduplication appliances deliver superior deduplication technology while reducing the complexity of backup administration and management. Purpose-built deduplication and compression appliances offer an affordable, powerful and easyto-use solution that can scale to handle growing data sets. They are designed to complement existing backup environments regardless of what backup software is being used, enabling compression and deduplication savings without rip-andreplace demands. Dell offers the DR Series of purposebuilt disk based deduplication and compression appliances that have a proven track record of satisfying customer backup needs. We invite you to learn more at software.dell.com/ solutions/deduplication-appliances. 6
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