Hitachi Data Systems Corp., a holdout on Serial Advanced Technology Attachment (SATA) technology for performance reasons, announced Monday that it has spent six months enhancing this format for an intermix
The new disks, which can be added to existing Thunder 9500V systems, enable users to pack high-speed Fibre Channel and lower cost SATA drives into the same storage array. The advantage? Users can route data from different applications to the most appropriate storage based on different criteria. Rivals Hewlett-Packard Co. and EMC Corp. offer similar capabilities.
HDS, a wholly owned subsidiary of Hitachi Ltd., claims it has gone one step further by improving the reliability of SATA technology so that users can use these drives and still sleep at night, a company spokesman said.
"All ATA is designed to be low cost, which means cheaper components and a less rigid system, which results in vibrations that are more likely to make heads misread and bearings wear down," said Hu Yoshida, chief technology officer at HDS. "Because of their flimsier enclosures, these drives are not designed to get a lot of pounding before you get a misalignment. … We were very concerned about putting this technology into an enterprise environment," he said.
To take care of these concerns, HDS built in several enhancements to its SATA drives. First, a read-after-write capability that isn't part of the ATA specification verifies every read to a disk after it has been written to ensure integrity of the data. It has also doubled the number of spare disks that it provides in a traditional SCSI system. While the standard is one spare per drawer, the HDS SATA option provides 30 spares that can be available to any drawer. Then it monitors the temperature, performance and vibration of the SATA disks and automatically replaces a bad one, copying the data to a spare before it burns out, according to Yoshida.
Another interesting enhancement to the SATA drive is the ability to prioritize sparing over normal data movement, which is the opposite of what happens in a SCSI system. "Because SATA is used for non-critical data activity, we give priority to the rebuild," said Yoshida. And when the disks are idle, the system moves the heads around to avoid wear patterns, and does a sweep every 10 minutes to clean the disks.
HDS hopes to sell the SATA option, which offers up to 107 TB in a single array, into the same market as EMC's Centera product for fixed content applications, such as e-mail archiving, database archiving, digital archiving by broadcasters or medical systems and disk backup. In these markets, the need for data integrity and availability is high, but access requirements are much less frequent than with operational data.
To meet regulatory compliance requirements, HDS also announced that it has added WORM (write once read many) capability to its LDEV Guard data retention software. This capability will allow users to lock down archived data, which makes it non-erasable and non-rewritable for the prescribed period, the company said..
The Thunder 9500 V SATA option is available now, on the Thunder 9570V, Thunder 9580V and Thunder 9585V. Example list prices for SATA intermix are $95,000 for 5 TBs (50% Fibre Channel and 50% SATA ), to $170,000 for about 3 TB (15% Fibre Channel and 85% SATA ). For most Thunder system configurations, SATA drives are around 40% cheaper than FC drives, the company said. Existing Thunder 9500V series customers will be able to add SATA drives after a software upgrade.
HDS said it has no plans to add SATA drives into its other product lines at this time. Analysts said that users looking for peace of mind when implementing SATA drives will find it with this product, but should expect to pay a premium for this enhancement over other SATA products on the market.
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