by Bob Fine, Director of Product Marketing — October 29, 2008

We understand – SSDs are expensive – but we’re making them work for users both in performance and affordability. When planning the launch of Compellent’s SSD solution, we pulled out all the stops to figure out how users could maximize efficiency, and ultimately we determined the drive approach would be most adoptable and scalable. See what Martin Glassborow had to say about what we’re doing on his blog. Only the most frequently accessed blocks of data (rather than complete LUNs or volumes) earn “tier 0” storage – it’s for applications that can really take advantage of the performance boost from SSD technology. Questions about how we are able to help our end-users manage this, look no further than this post from our CTO Larry Aszmann.

by Bob Fine, Director of Product Marketing — October 14, 2008

This week at SNW we announced a new business continuity automation feature we’re working on here at Compellent: Live Volume. Live Volume provides coordinated access to data stored on Compellent SANs – and it doesn’t matter where the data is actually housed or how far the sites are from each other. We believe this new technology will complete the server virtualization story by enabling storage to automatically follow the application wherever it is migrated.

Since Live Volume is fully automated, the setup is a simple process. In a virtual server environment, you configure VMs and map volumes for replication, and then you migrate virtual servers using an OS virtualization platform. (Compellent doesn’t require host-based agents or third-party software to support the virtualization platforms.) Following setup, Live Volume provides continuous data connectivity and automatically handles storage migration and connection optimization – all with no changes to the original applications.

Live Volume detects when the application has moved to another server located at the same site or to a different site and, if needed, automatically swaps the data access from the primary to secondary SAN. Here’s a screen capture of the beta version of the Live Volume GUI, which shows the storage migration underway. In the screen shot you can see Live Volume (shown with some development codenames) in the process of swapping the roles for two SANs. The Primary SAN (#908) is becoming Secondary while the Secondary SAN (#909) is becoming Primary. In normal operation, this will happen automatically when a major topology change has occurred, requiring no user intervention and a minimum amount of time.



We think the Live Volume technology fills a large void in the virtualization world and addresses the promise of the virtual data center: that data is available regardless of its physical location. Our development continues at a fast pace and Live Volume will evolve and improve as we work closely with early access customers and partners. Their feedback on operation, user interface options and best practice usage will all combine to a great launch of this product in Q2 2009. Stay tuned to this site over the next few months for more updates from industry voices, and to learn more about our technology innovations.

by Bob Fine, Director of Product Marketing — July 28, 2008

On our last post we were discussing specific features of Compellent’s thin provisioning solution, Dynamic Capacity. And today we’re continuing that conversation to discuss potential green benefits, recovery and reporting.

Does thin provisioning result in any green benefits?
Thin provisioning is a must-have technology for a cost-effective, green data center. By purchasing and operating fewer disk drives, companies can significantly reduce power, cooling and physical space costs. Using thin provisioning alone, without any other energy-saving features, can help companies reduce disk drive counts on just a single tier of storage by 75 percent. Analysts estimate the storage utilization rates for traditional SANs are as low as 25 percent.

For example, a typical storage system—without thin provisioning—might require 274 146-GB disk drives to provide 10 TB of storage capacity (assuming 25 percent storage utilization). By contrast, a Compellent SAN using thin provisioning with the same type of drives would require only 69 146-GB disk drives to provide the same usable storage capacity. Eliminating 105 disk drives from the data center can mean a significant reduction in energy consumption and carbon emissions in addition to the smaller footprint.

What about data migration and recovery processes?
Thin provisioning solutions can also improve efficiency and utilization when end-users transfer data from their legacy storage systems. For example, Compellent’s Thin Import feature in Storage Center 4.0 converts data from a “thick” provisioned volume to a thin-provisioned volume during the migration process. Unused space from the legacy volume is freed up to be allocated to another volume in the Compellent SAN.

In Windows environments, deleted files aren’t really returned to the storage pool even in thin-provisioned volumes. Often, users turn to a third-party utility to defrag the Windows volume to free up the unused space. Without these utilities even a thin-provisioned volume becomes thick. Compellent integrates a utility to recover this unused space called Free Space Recovery in Enterprise Manager, our SRM tool that automates replication, storage and green cost savings reports and chargeback, keeping volumes as thin as possible.

How extensive are management and reporting tools?
The Compellent SAN monitors capacity utilization in real time and provides information to administrators so they know exactly what the disk space consumption is at all times. The SAN sends alerts (like e-mail and text messages) based on pre-defined rules.

Enterprise Manager also shows storage utilization and consumption over a period of time including allocated space, used space and configured space for all disks and total space and used space for any RAID selection with any disk tier. Admins can also view ongoing CPU and memory utilization for each SAN to understand how utilization is affecting performance. They can generate “hero” reports to document storage ROI for senior management, charge back departments for storage utilization, and show savings on energy and carbon emissions.

As energy costs continue to skyrocket, we expect more customers to take advantage of thin provisioning technology as they start to realize the lowered disks and power and cooling costs associated with thin provisioning. Especially as organizations look to migrate data off of aging DAS and legacy SAN storage systems to more flexible next-generation storage arrays.

After reading this, are there still areas of thin provisioning that aren’t clear for you? Leave me a question, I’m happy to answer it.

by Bob Fine, Director of Product Marketing — July 25, 2008

Not all thin provisioning products are created equally—some are thinner than others. Industry experts like Rich Friedman at Storage magazine and Mario Apicella at Infoworld, recently posed interesting questions about different features, cost reductions and energy savings of thin provisioning solutions. Given this, we thought it would be helpful to explain Compellent’s approach and what makes our thin provisioning software, Dynamic Capacity, unique.

Diving into the virtual storage pool
Compellent manages data inside the volume, at a granular, block level. Dynamic Capacity works with our storage virtualization technology to make all physical disk space available to all volumes from a single shared storage pool. First, we spread read/write operations across all of the disk drives, rather than limiting availability to a single drive or group of drives dedicated to a volume. This means there aren’t the typical restrictions of RAID grouping or space pre-allocation. Users can create volumes of any size and number, and those volumes can simultaneously utilize all of the disk drives in the shared storage pool, resulting in better performance.

How does thin provisioning work?
Dynamic Capacity allows the creation of volumes without having to pre-allocate disk space. In other words, Compellent only allocates volume space when actually writing to disk. For example, if a server application requires 1 TB of storage, a customer can provision the space the application needs, even though there might be 500 GB of physical capacity.

So no more “islands” of storage?
Competitive thin provisioning solutions actually require end-users to pre-allocate physical capacity to create thin-provisioned volumes. Once the space is used up, the volume can’t be expanded. When unused it becomes an “island” of storage and can’t be returned to the storage pool, resulting in wasted storage space. Due to this, some vendors don’t enable or recommend their thin provisioning solution 100 percent of the time. To take advantage of the full benefits of thin provisioning, make sure the thin provisioning technology you are considering will always remove these “islands,” allow you to expand the volume on the fly and return any unused space to the storage pool.

What is the maximum pool size?
Compellent’s Dynamic Capacity has unlimited pool size.

What is the typical oversubscription ratio?
Ratios of real to oversubscribed capacity vary. Some users tell us they oversubscribe by 50 percent while others use a 2-to-1 ratio.

Another way to look at this is capacity planning – it’s not unheard of for thin provisioning users to plan 6-12 months in advance for drive purchases. They still allocate the volumes based on projected needs but they’d purchase fewer drives – often 50 percent fewer.

What about performance?
With thin provisioning, there’s less data being written to the disk, so common operations such as copy, replication and RAID rebuilds require disk access perform faster because they are based on actual data written within a volume instead of based on an artificially large allocated volume. The smaller the amount of data you have to write or re-write, the faster the performance. Some thin provisioning solutions, like Compellent’s, also match the chunk or page size of the data being written with your server application to optimize performance.

Consequently, Compellent thin-provisioned volumes can be expanded while the system is online without any downtime. Through automated tiered storage, the Compellent SAN can also dynamically move data to less-used disks if system bottlenecks occur. Compellent takes this a step further with Fast Track, because frequently accessed blocks are placed on the outer edges of drives to improve performance by as much as 30 percent.

What is the chunk or page size?
Compellent users can scale the chunk or page size from 512KB to 4MB depending on the server application. Smaller page sizes, like 512KB, improve performance for databases while larger 4MB page sizes improve performance for large I/O such as image processing.

To be continued…
In the next post we will look at green benefits of thin provisioning along with recovery process and reporting functions, so please stay tuned.

by Bob Fine, Director of Product Marketing — February 22, 2008

We hope you’ve all been following the launch of Compellent's Storage Center 4.0. We’re excited about all of the upgrades we've made and the potential the product has to impact the storage market . We've noticed from some of the articles that have run have compared one of our new features, Fast Track, to solutions already on the market, like this article. And to that, we’d like to take a couple of moments to provide some additional clarity on our Fast Track feature:

• Fast Track provides benefits far beyond short stroking. Fast Track does provide performance benefits similar to short stroking since data is written to the outer zones of the drive. However, Fast Track goes beyond short stroking by utilizing the full capacity of the drive as inactive data is placed on the inner tracks. All the benefits without the high cost of short stroking.
  
• Fast Track is fully automated and dynamic. The storage admin sets up the volume once through a few clicks and never touches it again. All blocks are analyzed daily to determine frequency of access. The most active blocks are moved to outer zones and inactive blocks are moved inward, automatically.
  
• Fast Track operates at the block level rather than a volume level. By working inside the volume, only the small portion of a volume that has the highest activity will be moved. Other storage products operate at the volume level, which requires movement of the entire volume.
  
• Fast Track leverages Thin Provisioning. This is very important since only the actual data is committed to the disk. Some vendors that lack thin provisioning must write the entire volume to the outer edge of the disk. Since only 20% of the total capacity provides the highest performance, a thick provisioning volume will typically consume more than just the outer zones, eliminating any potential performance gains.
  

Let us know what you think about Fast Track, Thin Import and other features of the new release.