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This page is seriously out of date.
LSI now has PCI-E gen 3 controllers with 12Gbps on the SAS side. HP is upto 43x series.

RAID Controllers and HBAs

This article on Tom's Hardware Dec 12, 2012, looks interesting. Intel Previews Its PCIe 3.0-Based RAID Cards

A host bus adapter, per description, adapter the host bus interface, now PCI-E (gen 2), which is nolonger a bus but a point-to-point protocol, to the IO channel. There are straight SAS HBAs, but most are also RAID controllers.

Note:The section on LSI controllers has been moved to the SAS section.

Dell

References: Dell PERC, PERC H700 and H800 Technical Guidebook (Dell PowerEdge RAID Controllers Cards H700 and H800 Technical Guide)

The Dell RAID controllers for PCI-E gen 2 and SAS 6Gbps are the PERC H700 Integrated or Adapter (2 x4 internal SAS) the H700 Modular (1 x4 SAS) and the H800 (2 x4 external SAS). The H800 has x8 PCI-E gen 2 interface with 512M or 1GB non-volatile cache.
  New features: Cut-Through IO (CTIO)
  Performance boosts (up to 2X IOPS performance),
  Optimized for superior IOPS of SSDs over HDDs,
  Ideal for small-block random workloads,
  Easy to enable The H700 Modular does not have NV-cache, uses the LSI 2108 ROC.

Cut-Through IO is an IO accelerator that boosts the throughput of devices connected to the PERC Controller. It is enabled through disabling the write-back cache (enable write-through cache) and disabling Read Ahead.

Redundant Path with Load Balancing Support
PERC H800 can detect and use redundant paths to drives contained in enclosures. This provides the ability to connect two SAS cables between a controller and an enclosure for path redundancy. When redundant paths exist, the controller automatically balances I/O load through both paths.

The previous generation Dell RAID controllers include the PERC 5 and PERC 6.

LSI 1078 LSI 1078
PERC H700 Integrated             H700 Modular

LSI 1078 PERC H800

The RAID controller NVRAM cache might be something like this.

LSI 1078

Instead of batteries, there is are super capacitors to maintain power to the memory chips until a controller can write the data to NAND. The super capacitors are a new technology capacitor that is a cleaner solution than battery backed cache. See supercapacitors.org and Wikipedia Electric double-layer capacitor.

HP

The HP PCI-E gen 2 SAS 6Gpbs RAID controllers are: P212, P410, P411, and P812. The HP Smart Array Controller technology (c00687518) brief provides some information.

The P212 is an entry model with 1 internal and 1 external x4 SAS port. "MIPS 32-bit Processor."

P410 and P411

The P410 has 2 internal ports, is probably the embedded model. The P411 has 2 external ports. The P812 has 2 internal and 4 external ports. "256 MB 40-bit wide DDR2-800MHz cache upgradeable to 512 MB 72-bit wide DDR2-800MHz battery-backed write cache or 512 MB / 1 G 72-bitwide DDR2 flash backed write cache provides up to 4.2 GB/s maximum bandwidth."

LSI 1078
P411

P812

The "P812 includes a PMC-Sierra SRC 8x6G SAS RAID-on-chip," "MIPS-based multi-processor subsystem," "Hardware XOR and Reed-Solomon Engines for RAID 5 and RAID 6 acceleration," "PMC-Sierra SXP 36x3GSec 6 Gb/s SAS Expander to support six Mini SAS connectors in one controller card."

LSI 1078
P812

SAS-2 (8 physical links at 6 Gb/s) The RAID controller has eight 6 Gb/s SAS physical links. Bandwidth is dynamically shared by the 24 physical links used in the 6 Mini SAS connectors DDR2-800 SDRAM (64-bit data and 8-bit ECC).

From the above Technology brief, HP P411 versus P800 RAID-0 Performance.

x

x

x

HP has an option for Flash-backed Write Cache (FBWC) that uses super capacitors.