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Because servers can consume stored data faster than hard disks can provide it, companies are driven to add more disks to boost performance. They may not actually need this additional disk capacity, but more spindles increase the throughput of the system.
"You end up buying more hard drives to get the same level of IOPS as one SSD, and those drives require more space, power and cooling," says Janukowicz.
For example, STEC compared HDD and SSD in a high IOPS application. It found that a company would need 450 73GB disk drives to generate the same level of IOPS as 15 146GB SSD drives.
The cost for those 450 hard drives, according to STEC, would be $175,000. STEC pegged the cost of the 15 SSD drives at $187,500. But if you throw in the cost of the multiple enclosures, racks, cables, transceivers, controllers and SAN switches necessary to house and connect all of those hard drives, the total HDD cost comes to almost $413,000 in STEC's calculation. The total SSD cost--which requires only one enclosure, rack, cable, transceiver, controller and switch--comes to a bit more than $201,000. In STEC's analysis, the SSD solution costs half that of the HDD solution. Of course, the HDD solution delivers substantially more storage capacity in the process.
Texas Memory Systems is also targeting the enterprise storage market with its RamSan-500 SSD device, which delivers 2TB of SSD storage with
| two FC controllers for $300,000. It boasts 100,000 IOPS, but its best performance comes from its 16GB of very high-performance DDR cache. The rest of the 2TB capacity consists of less-costly flash SSD.
The issue actually goes beyond storage. Organizations are buying servers that are poorly utilized in part because the storage can't feed data to the server fast enough.
"This results from the latency of rotating disk vs. the speed of the server's processor," says Janukowicz. "With SSD, the latency issue goes away. Where you might have used two servers [each running at a low level of utilization], you would need only one." With SSD, companies could reduce the number of servers they need in certain situations.
This was first published in November 2007