Electronic Design
Low Cost SAS RAID Controller Handles SDD/HDD Mix

Low Cost SAS RAID Controller Handles SDD/HDD Mix

Adaptec is well known for its storage controllers and chips. It is now part of PMC-Sierra. Adaptec's latest offerings include the low cost, entry-level Series 6 four-port 6405E and eight-port 6805E adapters (Fig. 1). These host bus adapters (HBA) utilize PMC-Sierra's PM8013 SRC 6Gbit/s RAID-on-Chip.

Both boards have PCI Express 2.0 interfaces and support SAS and SATA solid state disks (SSD) and hard disk drives (HDD). They support RAID 0, 1, 1E, 10 and JBOD. HBAs provide support for Adaptec's Hybrid RAID configurations with a mix of SSD and HDD. Hybrid RAID can handle a mix different size SSD and HDD drives. The hybrid approach is SSD aware so reads come from the faster, SSD drive. The boards also have 128 Mbytes of DDR2-800 DRAM memory for on-board caching. Together the DRAM,SSD and HDD deliver a three level storage hierarchy (see The Storage Hierarchy Gets More Complex).

The four-port 6405E HBA has a x1 PCI Express interface that delivers a 400 Mybte/s throughput. The eight-port 6805E HBA has a x4 PCI Express interface that delivers a 1600 Mbytes/s. The heatsink on the PM8013 SRC chip can mount a standard cooling fan. This can be handy in embedded applications where cooling is critical or where the processor and power supply are using a minimal cooling system to keep cost and noise low.

The boards support a range of operating systems including Windows and Linux. Open source drivers are provided for Linux. The HBAs are supported by the multiplatform, Java-based, Adaptec Storage Manager (ASM). ASM provides remote management for all Adaptec adapters. IPM remote power management is standard. Pricing for the four port 6405E starts around $200.

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