Posted by: Dave Raffo
Are lithium-ion batteries running out of juice as a method to protect cache in storage arrays?
There’s probably still a lot of life left in batteries in arrays, but Adaptec today unveiled an alternate approach. The Adaptec Series 5Z RAID controllers use flash memory powered by a super capacitors instead of batteries.
Capacitors store energy until they need it, and provide enough power to destage data to Flash disk. This differs from batteries, which are in constant use, requiring monitoring, and lose power over time. Adaptec director of marketing Scott Cleland says the super capacitors last longer and require less maintenance and lower operating costs than batteries. Adaptec expects to sell the 5Z controllers through integrators and resellers, mostly in entry level and remote office systems.
“Having a battery has been a necessary evil,” Cleland said. “It goes against everything RAID stands for. RAID is about availability without touch.”
Cleland says the 5Z controller is “like having a USB stick on steroids integrated in a system.”
Adaptec isn’t the first storage vendor to use a capacitor in place of batteries. Dot Hill Systems introduced a storage controller with super capacitors two years ago, and recently was granted a patent for a “RAID controller using capacitor energy source to flush volatile cache data to non-volatile memory during main power outage,” according to a vendor press release issued today. Fujitsu also uses a capacitor to back up cache in its Eternus DX midrange storage systems.
“Today it’s available in SANs,” Cleland said. “We’re making it available for everyone else – in appliances, the departmental space, SMBs, not just the high-end Fibre Channel space.”
But Data Mobility Group analyst Joe Martins wonders if this is a solution in search of a problem, because battery life isn’t a big complaint among storage administrators. Still, Martins thinks capacitors can catch on if they work as advertised.
“I never knew it was a problem,” Martins said. “I suspect that this is one of those undercurrents where people don’t know they have the problem until you point it out. It’s like when using Windows you become accustomed to the screen freezing, and after awhile it’s just something you get used to. It’s not thought to be a problem until you encounter something else. A lot of folks may not like the situation as it is, and they may have lost data and travelled miles and miles to get to a data center and thought ‘this is the way it is, there’s no alternative.’ Maybe it will become a requirement as more vendors do it.”
Of course, larger vendors must embrace capacitors before they become a requirement.