Navigating From All-Disk to All-Solid State Storage
A common put-down for sports wannabes is that they are "all flash and no substance." But for those contemplating moving off disk-based storage once and for all, the trick is to arrive at all-flash with plenty of substance. So how do you pull off this feat, and in the meantime, what do you do with all that expensive storage gear that was purchased not so long ago?
Here are some tips from the experts to help you along the way. They will help some of you arrive at that fabled haven where all-flash arrays (AFAs) have completely supplanted disk. For others, disk arrays and solid state storage will have to live in harmony for some time to come.
Take it Slow
It’s quite likely that some storage managers have been told by some over-enthusiastic CEO to go all-flash NOW! But that may not be the wisest choice. It takes time to come to terms with the intricacies of AFAs, so get to know them, gain confidence and then increase their share of the storage pie once you understand the beast.
“Keep your options open and give yourself the flexibility to fine-tune the mix of flash and HDD to find the optimal performance and ROI for your specific circumstances,” said Kevin Liebl, vice president of marketing, Zadara Storage.
Find Your Ratio
There are certainly clear business cases when all solid state storage makes sense. Examples include those whose entire business is all about the highest levels of performance, those with relatively minor investments in disk arrays and those with a lot of aging and almost obsolete arrays. More than likely, those considering all-flash have more than one of those factors in play. But for the rest of us, 100 percent flash may not be optimum. It’s all about finding the right ratio now and adjusting it in the future as requirements change.
“Many users find that their perfect ratio will change over time,” said Liebl. “You can change your ratio as your I/O demands change over time.”
Part of the flash preparation process includes extensive testing. Liebl recommends that users prepare to test AFAs over an extended period of time. They should test during month-end, or during peak periods when applications are hitting data hard.
“It is difficult to run a simple test to determine whether an AFA will solve an application’s I/O bottleneck,” said Liebl. “It is like interviewing an employee for 45 minutes to determine if they will become a good employee for the next five years.”
Some buy an AFA because it’s the latest and greatest. They throw it at their highest-performing applications and don’t give a thought to how it will integrate with the rest of the storage infrastructure. That was fine in the early days of the technology. But these days, careful planning is required so that the steady onslaught of solid state storage causes the least havoc.
“If you’re moving from a large disk architecture to all-flash, what you want is to find a flash array that has the ability to migrate the disk array to flash, and integrate with the array non-disruptively,” said Keith Parker, Violin Memory’s director of product marketing.
There could be a nasty surprise lurking for unsuspecting storage managers if they don’t pay attention to flash endurance. This essentially deals with the usable life of flash media. With a traditional hard disk, there is no set amount of times that it can be written to and read from. However, there is a limit to the number of times you can write to solid state storage. So it makes sense to know your flash and how it deals with the subject of endurance. Does the flash you’re looking at have active management to intelligently distribute the writes so that over time it won’t fail during the useful life of the storage? SSD-based arrays typically don’t provide this as they have a controller chip that does things like managing garbage collection. That potentially introduces a factor out of your control.
“In the middle of your day, your SSD could go into garbage collection and then your performance goes off a cliff,” said Parker. “Make sure your flash array manufacturer has access to the flash and is able to control things like garbage collection that so your applications are not impacted.”
Demand Vendor Help
If someone is pushing you to dump disk and buy a bunch of all-flash arrays, it might be wise to ask that vendor what they are going to do to help in the migration process. Some provide an easy migration path when moving from disk to solid state storage, helping you replicate data with various services to simplify the process. Others leave you in the lurch to deal with all the heavy lifting, or charge more for the privilege.
“Look for a flash-based product that can use integrated software to migrate data from your old array to the new one,” said Parker.
Divide and Conquer
Flash and disk serve different purposes within a storage infrastructure. Flash is best leveraged for performance and latency sensitive applications while disk is best used for capacity centric applications.
“Implementing flash as a bolt-on approach to existing HDD systems isn’t optimal and ends up hurting both performance and capacity” said Dan Leary, vice president of products and alliances, Nimble Storage. “The best approach to making the transition to all-flash is to select a single architecture that allows end users to cost effectively increase performance and capacity for the variety of workloads (applications) within a data center.”
Follow the Big Boys
Lee Caswell, vice president of product, solutions and services marketing at NetApp, suggested that users do what large providers of hyperscale environments are doing concerning the introduction of flash into their massive infrastructures:
- Introduce flash for performance workloads.
- Integrate flash with disk and cloud for backup.
- Add flash for consolidated virtualized workloads.
New Tricks for Old Dogs
Storage folks certainly know a thing or two about SAN and NAS. They can get into the mindset that they know it all. Perhaps the best approach is to show them how solid state storage can address some of their more pressing challenges. For those that can’t afford to upgrade their SANs, said Caswell it is possible to put some SAN workloads on a flash array. That can open the door to more willingness for broad scale flash adoption.
Photo courtesy of Shutterstock.