A couple of weeks ago SEPATON demonstrated OpenStorage (OST) at Symantec Vision and I posted a blog entry including a link to the demo. I wanted to explore OST in more detail.

OST is Symantec’s intelligent disk interface. It works with all types of disk targets and is most commonly implemented with deduplication enabled storage. OST addresses disk as disk and is different from the traditional tape-based metaphor. It handles backups as images and allows the backup application to simultaneously read and write data and incrementally deleted expired information. OST enables access to NetBackups native disk features such as San Client Backups, Media Server Load Balancing, Intelligent Disk Capacity Management and Storage Lifecycle policies. These are features of NetBackup that can benefit end users and are outside the scope of this blog. In this post, I want to discuss the features that are unique to OST.

The challenge that end users grapple with is how to move or transform data using their backup appliance while maintaining NetBackup (NBU) catalogue consistency. This can be a particularly difficult when using appliance-based tape copy or replication. OST addresses these issues by enabling the appliance to access the NBU catalogue. This means that NBU can instruct the appliance to replicate a copy of the data and maintain separate retention policies on the two copies. Let’s look at these features in more detail:

Optimized Duplication – Yes, this is really the name and I did not mistakenly exclude the “de” before duplication. This is Symantec’s name for intelligent replication. The technology enables a deduplication appliance to replicate only deduplicated data to a remote site while maintaining catalogue consistency. It simplifies the process of replication and management.

Open Storage Direct-to-Tape – In the past, vendors have promoted the ability to create physical tape copies without the intervention of a media server. This capability was promoted as a way to overcome bandwidth constraints, but it created a management challenge because NBU’s catalogue was not involved in the tape creation process. OST enables the VTL appliance to create physical tapes directly in a catalogue consistent fashion. It also allows for different retention times on the VTL resident and tape resident images.

Optimized Synthetic Full Backups – Synthetic Full Backup has been a feature of NetBackup for years. The technology enables NBU to create a new full backup based on the full backup and subsequent incremental backups. The challenge with the initial implementation is that substantial disk or tape I/O operations were required to create the synthetic full backup. The new feature takes advantage of the pointer based technology used within many deduplication and allows the appliance to synthesize the full in an automated fashion. Like the previous two examples, the synthetic full would be created in a catalogue consistent manner which simplifies its creation and management.

All of these features are unique to OST. However, it is critical to note that just because a vendor supports OST does not mean that it supports all of these features. Each vendor must write their OST plugin and decide which of these features to support. Today, the vast majority of OST implementations support Optimized Duplication while very few support Open Storage Direct-to-Tape or Optimized Synthetic Full Backups. When considering a solution you should discuss your vendor’s implementation and the features they support. If you are wondering about SEPATON, we will support all of these features over time.

Symantec should be recognized for their work on OST. They have created a technology that provides real customer benefits. They also should be acknowledged for the openness of the technology. They have made OST an open standard and encouraged all disk vendors to adopt the technology. This provides customers with the choice to choose the OST enabled solution that best works for their environment.

Related posts:

1. Video Demo: SEPATON and Symantec OST
2. Perspectives on Quest Acquiring BakBone

There is an interesting blog discussion between Dipash Patel from CommVault and W. Curtis Preston from Backup Central and TruthinIT regarding the increasing or decreasing benefits of deduplication ratios. They take different perspectives on the benefits of increasing deduplication ratios and I will highlight their points and add an additional one to consider.

Patel argues that increasing deduplication ratios beyond 10:1 provides only a marginal benefit. He calculates that going from 10:1 to 20:1 results in only a 5% increase in capacity efficiency and suggests that this provides only a marginal benefit. He adds that vendors who suggest that a doubling in deduplication ratios will result in a doubling cost savings are using a “sleight of hand.” He makes an interesting point, but I disagree with his core statement that increasing deduplication ratios beyond 10:1 provides only marginal savings.

Preston responds to Patel by suggesting that there is a real cost to purchase, manage and power/cool disk systems. An increase in deduplication ratios from 10:1 to 20:1 reduces the amount of required disk storage by two. (e.g. 10 TB at 10:1 requires 1 TB of disk while a 20:1 reduction would require .5TB disk.) He argues that this provides real management cost, power and cooling savings. I believe that Preston makes a good point, but there is another element that is also worth considering.

Most end users purchase deduplication with an end goal of replicating their data for disaster recovery purposes. The benefit of deduplication is not just about retaining data locally, but also about reducing bandwidth requirements for replication. The implications of going from 10:1 to 20:1 can have a major impact on replication and disaster recovery and in some cases can make the difference between meeting or missing SLAs. If we take the same example above, 10TB will shrink to 1 TB and will take 49.4 hours to replicate over a T-3. The same math with a 20:1 ratio yields 24.7 hours. (The model assumes that the T-3 delivers 45 Mb/sec and can be fully utilized for backup.) In this scenario, if the customer’s requirement is to get data offsite in 24 hours, they barely miss it with 20:1 and completely miss it with 10:1. If the deduplication ratio were to increase by one point to 21:1, the customer could replicate their data in 23.5 hours and meet their window. As you can see, in this case, data reduction ratios really matter. In fact, they are critical to the customer meeting their SLAs.

In summary, I believe that Patel is wrong in his assessment of deduplication ratios. Increasing ratios can and will have a meaningful impact on customer environments and suggesting that the benefits only result in 5% savings is misleading.

Related posts:

1. TSM and Deduplication: 4 Reasons Why TSM Deduplication Ratios Suffer
2. DeltaStor Deduplication, cont….
3. DeltaStor Deduplication

With all the recent hype, you may have missed that SEPATON launched DeltaRemote a couple of weeks ago. DeltaRemote is a software upgrade for existing DeltaStor users and enables deduplicated replication between SEPATON VTLs. Some of the new features include:

• Multi-node support – DeltaRemote leverages SEPATON’s DeltaScale architecture to use multiple nodes for replication. It’s fast and concurrent just like DeltaStor.
• Fast restore performance at the remote site – I have discussed in the past how DeltaStor has some unique features to enable industry-leading restore performance. The same technology has been extended to the VTL on the remote site.
• Simple management –Manage replication through SEPATON’s existing GUI. Detailed reporting and 30 day bandwidth efficiency analysis make planning and optimization a snap.
• Cartridge level control – DeltaRemote provides complete tape cartridge level control of replication and recovery. You can easily set replication policies or manually choose cartridges to replicate or recover in the same format as tape libraries.

Stay tuned for more detailed information on DeltaRemote.

Related posts:

1. The hidden cost of deduplicated replication
2. Recent Comment

Recently an end user commented about how the replication performance on his DL3D 1500 was less than expected. As he retained more data online, his replication speed decreased substantially and EMC support responded that this is normal behavior. This is a major challenge since slow replication times increase replication windows and can make DR goals unachievable.

The key takeaway from the comment is that testing is vital. When considering any deduplication solution, you must thoroughly review it with limited and extended retention. In this case, the degradation appeared when data was retained and would not have been found if the solution was tested with limited retention. The key elements you should test include:

1. Backup performance
   1. On the first backup
   2. With retention
2. Restore performance
   1. On the first backup
   2. With retention
3. Replication performance
   1. On the first backup
   2. With retention

Related posts:

1. The hidden cost of deduplicated replication