Why ExaGrid Versus Backup Software Deduplication

All IT departments want to back up to disk versus tape. Data deduplication greatly reduces the amount of disk required by only storing unique bytes or blocks from backup to backup. Over an average retention period, deduplication will use about 1/10th to 1/50th of the disk, depending on the mix of data types. On average the deduplication ratio is 20:1.

All vendors need to offer data deduplication in order to reduce the amount of disk to lower the cost to be about the same as tape. However, how deduplication is implemented changes everything about backup.

Deduplication in backup software is typically performed on the client server, on the media server, or both.

The deduplication rate for most software is an average of 6:1 to 7:1, much lower than hardware appliances, as the hardware is not dedicated and therefore the software vendors typically employ deduplication algorithms that are less aggressive in order to run on non-dedicated backup and media server hardware, running general purpose operating systems on top also running all of the backup processes. As a result of lower deduplication rates, backup software deduplication will use far more disk to store the deduplicated data and far more bandwidth to replicate data offsite. The longer the retention period, the higher the cost will be for onsite disk and for WAN bandwidth to replicate data offsite.

In addition, deduplication in the backup software deduplicates the backups inline during the backup process. Deduplication is a compute-intensive process and slows backups down, which results in a longer backup window. Furthermore, if deduplication occurs inline, then all the data on the disk is deduplicated and needs to be put back together, or “rehydrated,” for every request. Local restores, instant VM recoveries, audit copies, tape copies, and all other requests take hours to days. Furthermore, these solutions only add disk as data grows. Since additional compute resources are not added, as data grows, the backup window expands until the backup window becomes too long and then the media server has to be upgraded to a bigger, faster, and more expensive media server.

Backup Software Deduplication

ExaGrid understands that deduplication is required, but how you implement it changes everything in backup. ExaGrid has a unique landing zone where backups can land straight to disk without any inline processing. Backups are fast and the backup window is short. Deduplication and offsite replication occur in parallel with the backups by using available unused resources. Deduplication and replication never impede the backup process as they always are second order priority. ExaGrid calls this, “adaptive deduplication.” Since backups write directly to the landing zone, the most recent backups are in their full undeduplicated form ready for any request. Local restores, instant VM recoveries, audit copies, tape copies, and all other requests do not require rehydration and are as fast as disk. As an example, instant VM recoveries occur in seconds to minutes versus hours for the inline deduplication approach. ExaGrid provides full appliances (processor, memory, bandwidth, and disk) in a scale-out GRID. As data grows, all resources are added, including additional landing zone, bandwidth, processor, and memory as well as disk capacity. The backup window stays fixed in length regardless of data growth, which eliminates expensive server upgrades. Unlike the inline, scale-up approach where you need to guess at how much server hardware and storage is required, the ExaGrid approach allows you to simply pay as you grow by adding the appropriate sized appliances as your data grows. ExaGrid has 10 appliance models and any size appliance or any age appliance can be mixed and matched in a single GRID, which allows for IT departments to buy the compute and capacity as they need it. This approach also eliminates product obsolescence.

ExaGrid’s approach takes the same rack space, same power and cooling, and is the same or lower price.

ExaGrid thought through data deduplication implementation and created an architecture that provides for the fastest backups, restores, recoveries and tape copies; fixed the backup window as data grows; and eliminated forklift upgrades and obsolescence, while allowing IT staff to buy what they need as they need it. There is no downside and only upside. ExaGrid has taken the stress out of backup storage.

Backup Software Deduplication