A one terabyte SAS drive that isn't has been launched. We find out more from Seagate's engineers.
We met with Seagate today as they launched a refresh of the Barracuda series of hard drives, which are available in capacities of up to a terabyte. The new line of Maxtor One Touch external drives was also launched.
The most interesting announcement was the Barracuda ES.2 line, which on the surface is a standard consumer grade Barracuda 7200.11 (also launched) with better fault management, lower power consumption, a raft of interesting features and availability in both SATA and SAS interfaces.
The ES2 introduces iRAW, a technology that kicks in when the drive becomes too hot. Because writing data generates more heat than reading, once it hits 57 degrees celcius it will start to read what it writes on the fly to check write consistency and reduce temperatures. Firmware security features are included so that the drive will only install authorised firmware updates, and the installation time has been reduced to three seconds to decrease the likelihood of bricking the drive during flashes.
The SAS edition of the Barracuda ES2 will be the lowest end SAS drive available, because fundamentally it is still a high end consumer grade drive. The difference between it and the SATA version is that its controller circuitry will be swapped out in exchange for SAS electronics. Although internally the platters and heads won’t compare to industrial SAS specifications, in theory the latency will be reduced when used with a SAS controller as the native drive interface means less translations during use which is accompanied by lower latency.
As a result, the SAS version of the Barracuda ES2 will be aimed at utilising workstation boards with integrated SAS controllers to improve performance while keeping costs down. Although it won’t perform as well as a high RPM SAS drive it still supports dual interfaces for controller redundancy and sports a better MTBF than the lower end Barracuda 7200.11, as it is more resilient to vibration and uses less power. These qualities are what data centres look for, and the introduction of a SAS drive with a large capacity (either 250, 500, 750 or 1000 GB), low price and (relative to 15K SAS drives) low performance will appeal to many IT managers.
After chatting to Sam Zavaglia, a Seagate engineer, we were able to uncover some interesting facts about hard drive reliability measurements. Consumer drive MTBF (Mean Time Before Failure) rates are measured at a 5% duty cycle, while the drive hovers at an average temperature of 25 degrees celsius. SAS (Serially Attached SCSI) drives are tested at 100% duty cycle at full temperature. When the MTBF and of a drive is graphed against its operating temperature, the failure rates increase exponentially - a reflection of the research and development that goes into enterprise drives.