Like many other parts of the IT industry, the storage industry has had its fair share of disruptive technologies over the years. The latest is flash and all-flash arrays. There are all kinds of claims being made for all-flash arrays. Maybe you’ve heard some of them. Like the one that they can run your OLTP apps 4,000% faster? Or the one that claims they can save $4m per annum in power costs?
The trend went this way a few years ago with ‘cheap and deep’ SATA drives while this year it’s heading the same way with all-flash arrays. Flash is a new media technology and it certainly has its place however it’s not going to take over the storage world. It’s a great tool to help solve some storage issues but it’s not a one-size-fits-all solution. Organisations need to make they are not swept up by the hype surrounding flash. The reality is there is still plenty of mileage left in hard drives.
With SATA, after many years stuck in the cycle of replacing three-year old 15K RPM FC drives with some newer 15K RPM drives, lower-cost options for wide-striping more cost effective SATA drives generated some excitement. For many organisations this led to an imbalance – low capital costs versus ridiculously high operating costs and, in some cases, business disruption. This is often the case when architects and designers look to promote the use of a trending new tool as the next big solution.
There’s no doubt SATA drives have a place in the data centre, but they are not suitable for primary use where risk and performance are critical. They’re great for backup and archive where the performance hit of RAID-6 can be tolerated and businesses can handle downtime, but other than that, it’s buyer beware. All too often we’ve seen key workloads such as OLTP apps and VDI sitting on SATA where reliability or growth issues have seen systems grind to a standstill and cause serious impact to the customers’ business.
Fast forward to today and a multitude of new vendors are shouting from the rooftops that flash is our true saviour of the storage universe. Among other things, I’ve heard outlandish claims that all flash arrays can do everything from run your OLTP apps 4,000% faster to saving $4m per annum in power costs. Sounds impressive but are they right or is this just another extreme example of a tool being positioned as a business solution?
In a recent real-world customer test, a hybrid 10TB unit had the same performance as all-flash 10TB units from two vendors but used less than half the power and gave out less than half the heat. Most crucially for businesses in a world of tightening IT budgets, the hybrid unit cost around 70% less than the flash-only alternatives.
One of the major inhibitors to adopting flash arrays is price. In a recent survey, the high costs associated with all-flash arrays was cited by three-quarters (75%) of IT managers surveyed as the single biggest barrier to deployment, should they consider it in the first place. To save costs, businesses could opt for cheap, consumer grade flash-based products with short duty cycles but that’s a risky move and few are likely to take it.
For those that do consider it, businesses should be aware of the risks they are taking. No matter much software is wrapped around consumer-grade flash, it’s still a major concern and adds far too much risk for enterprise environments. Most UK businesses (99%) would not permit consumer-grade flash in their enterprise storage arrays.
Another area worth exploring in more detail is power and heat. Two thirds of respondents (75%) believed that using less power and cooling is the second main difference after speed between all-flash and hybrid storage. But real-life testing by users has found that hybrid arrays use half the power of all-flash arrays in like-for-like evaluations. Flash modules/SSDs draw less power as raw components than hard disk drives, but enterprise storage arrays are not just raw storage.
One vendor claims its flash modules use only five watts per TB of storage. By those figures, someone might expect a 10TB array would only require a 50W power supply. However, that figure doesn’t include the processors needed to run the unit, some of the background issues (write endurance and garbage collection) that need power too, as well as the on-board memory. Once you add all those in, a 10TB all-flash array could need nearer 2KW of power.
And it’s not just one flash-only array vendor pushing the power angle, it’s pretty much all of them. It’s hard to blame them. The space it super hot – EMC reportedly bought XtremIO in 2012 for close to a half billion bucks without having shipped a system.
But, from the user’s perspective, it’s essential to keep a cool head and pragmatic perspective when it comes to deploying flash.
The common myth that enterprise flash storage uses less power than hard drive arrays may have been true of some of the old-school 15K RPM Fibre drive units, but it’s not the case with new hybrid arrays. Hybrid arrays help overcome power consumption issues by combining different media technologies together, including flash, and playing to the strengths of each of them.
The other aspect to consider is length of warranty offered. Flash-only warranties typically tend to last one year as standard. Hybrid arrays offer five-year warranties as standard, which demonstrates a far higher degree of confidence.
A five-year warranty ensures you’re buying into an architecture that can provide crucial uptime to the business. Hybrid can deliver this thanks to its non-reliance on a single media type along with, of course, some clever software stuff that self-heals hard drives.
With flash grabbing all the headlines, here are a few tips how not to lose your head. When considering flash-only arrays, ask yourself:
- Do you need 1,000,000 IOPS in 10TB of storage? Really?
- Do you need 300µS latency? Really?
- Can you justify to your boss a £300,000 outlay for something that comes with a 1 year return to base warranty? Really?
For the majority of users today, for now, it’s probably best to use flash where it’s appropriate and as a tool rather than a solution. Of all the trends we’ve witnessed in storage the one thing we probably all agree on is how to avoid ‘overspend on a storage trend’. Opt for tried and tested, rather than choose trial and error. This approach should be plenty good enough for most of us.