Friedrich Miescher Institute (FMI) for Biomedical Research in Basel, Switzerland, learned the hard way about MAID's drawbacks. FMI uses the Copan Revolution 300T virtual tape library (VTL) to store large sets of DNA sequencing data and microscopy images. FMI fronts the system with Sun Microsystems Inc.'s SAM-FS (now owned by Oracle Corp.) highly scalable clustered file system to create a "bottomless NAS," according to Dean Flanders, head of informatics at FMI.Because of the space and cooling constraints at its main data center, energy efficiency was high on FMI's priority list during the product evaluation stage. The density of the Copan VTL was appealing, allowing FMI to store 40 TB in a 3U enclosure. The dense storage, coupled with virtualized blade servers, even proved helpful on one occasion earlier this year when FMI's cooling unit failed. FMI simply installed a small room air conditioner and opened the door while waiting for the fix. Copan's MAID technology was also enticing, with its potential to reduce power consumption. But FMI gradually found the power savings didn't compensate for the 16 seconds of disk spin-up time and the periodic time-outs that scientists experienced when copying large amounts of files. Flanders said he fields two or three complaints each month, and worries about the ones that might not reach him. "I would not recommend using MAID for a file system," said Flanders. "It's perfectly fine for backups or off-line data." FMI recently purchased a Nexsan Corp. SATABeast, with a 60-drive extension tray, to eliminate the spin-up latency, better meet its scalability needs and afford greater flexibility to use different types of drives, such as SAS disks and solid-state storage. FMI plans to gradually migrate off the Copan VTL to the Nexsan storage as its data footprint continues to climb 25% per year. Flanders said even though the Copan VTL consumes less power than the Nexsan SATABeast, it's not a significant enough difference given that both consume considerably less than a traditional disk array. Flanders estimated that he will get more than 50% power savings with the Nexsan storage over traditional disk trays. FMI still plans to use MAID technology, but this time, it won't spin down the disks completely as it did with its Copan system. Instead, Flanders said, FMI will use a MAID level that parks the heads and leaves the disks spinning, even though it will not save as much power as its Copan system did. "MAID is overrated," Flanders said. "The majority of the power consumption savings is not from spinning down the disks. It's from using power-efficient disks and fewer power supplies."
This was first published in July 2010