Adaptec designs storage adapters to work better with SSDs

Adaptec announces a pair of Unified Serial adapter cards that are cheaper than its existing SAS HBAs because they do not include RAID functions

Adaptec is targeting pure storage connectivity with a pair of Unified Serial adapter cards, which it said are also designed to get the most out of solid-state disks (SSDs).

The four-port PCI Express HBAs support both SAS (serial attached SCSI) and SATA devices, but are cheaper than Adaptec's existing SAS HBAs because they do not include RAID functions.

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It's an acknowledgement that not all storage devices warrant the cost and overhead of RAID, said Juergen Frick, the company's EMEA product marketing manager. Some (for example, tape drives) simply don't need RAID, while others such as disk arrays may do it themselves in hardware.

He added that while many servers and desktops now have SATA built in, SAS allows longer cables, higher speeds, and many more devices. For example, the new HBAs can support up to 128 SAS devices if SAS expanders (hubs) are used.

Each card has four 3Gbps SAS/SATA ports. The model 1405 has an internal connector only, while the 1045 has an external connector only. They are four-lane PCI Express, giving them around 8Gbps on the system side, Frick said.

According to Adaptec, the new cards are likely to cost end-users less than €150 ($190), and will come with drivers for recent Windows versions, Red Hat and Suse Linux, and FreeBSD.

Frick said that Adaptec has changed its driver architecture to make its adapters work better with SSDs. He claimed that SSD performance can suffer dramatically if they are used with controllers that expect them to work the same as spinning hard disks.

"We delayed the launch of the adapters to test them with SSDs," he said. "SSD has a unique performance profile -- it's very good on reads but only average on writes. We hear from system integrators that if they connect SSDs to a SATA card or motherboard chipset, they don't always get the performance they expected."

A particular problem is storage adapters such as RAID cards that use caching to speed up disk access. Frick said that, if used with SSDs, these can actually make disk access significantly slower.

He added, "You can only deliver high SSD performance with a direct connection."