Next month the company will begin offering 750GB SATA disk drives as an option on its flagship USP disk arrays.
Hitachi’s major high-end rivals EMC and IBM have been offering SATA for their flagship boxes since respectively 2005 and 2006, or more specifically, drives that combine low-cost, high-capacity ATA mechanical components with Fibre Channel electronic interfaces.
But until now Hitachi has said that such drives have not reliable or fast enough for tier-one applications, and that the USP shouldn’t be used to store data for any other type of application.
Now Hitachi says that SATA-2 drives are approaching the reliability of Fibre Channel drives.
Analyst Nick Simpson at the Burton Group said that he was still sympathetic with Hitachi’s original philosophy. Adding a SATA option to the USP does allow you to create multiple tiers inside the box, but it’s pretty crude. I think this is more about Hitachi filling out a customer check-box than making a significant change of philosophy, he said. Using SATA drives inside a big box doesn’t do much good. Tiering across two boxes, where one box is much cheaper, buys you much more.
Drive makers quote the lives of their products as mean time between failure or MTBF hours, and these numbers are based on statistical analysis of failures encountered in the field. As the population or number of devices in the field increases, and as they clock up running hours, the MTBF numbers that come out of the statistical calculations increases.
Hitachi said that this is one of the reasons why SATA-2 reliability is nearing that of Fibre Channel. But MTBF calculations involve assumptions about the duty cycle or workload applied to devices, and drive makers assume different workloads for SATA and Fibre Channel drives. Hitachi did not discuss that issue.
Separately, Hitachi said that it has extended the use of thin provisioning function in its disk virtualization software to cover third-party external disk arrays attached to the UPS and its diskless variants. Disk arrays from all the major suppliers including EMC, HP, and IBM has been qualified, Hitachi said.
