If you remember some of our storage controller roundups, and the review of the initial Fulcrum/RAIDCore storage technology, then you will know that we’re talking about enterprise-class RAID functionality. The firm brought into the mainstream what had previously been found only in the form of expensive SCSI RAID controllers.
One RAID Layer, Multiple Controllers
RAIDCore designed its Fulcrum architecture to run only on RAIDCore controller cards. Since the architects created a host-based RAID solution, meaning that the entire load for operating RAID storage arrays is processed by the system processor, the RAIDCore solution is flexible enough to span RAID arrays across multiple RAID controller cards, utilizing all available ports. In the article Tom’s Hardware Pushes Broadcom’s RAIDCore Storage Controller Envelope you can read about a project in which we created RAID 0 and RAID 50 arrays using four RAIDCore controllers and as many as 32 hard drives.
We would like to shed some light on the different implementations of RAID technology today. As already mentioned, the RAIDCore technology is designed as a host-based RAID solution , which runs on a dedicated software layer, requiring the system CPU to take on the storage processing load such as for the XOR calculations needed for RAID 5 or RAID 6.
Software RAID refers to implementations that are a part of the operating system. All Linux and Windows server solutions support RAID 5, using all available interfaces and storage controllers that are installed and operational. This offers a quick way of creating RAID arrays, but maintenance and handling in the case of a drive failure or migration to other controllers or systems may be tricky.
Finally, most RAID controllers sold by the big vendors are based on hardware RAID and consequently include a so-called storage processor, which can be based on different designs. Intel is currently phasing out its Xscale processors, but there are alternatives from AMD and others. AMCC utilizes a PowerPC-based solution to accelerate XOR calculations.
RAIDCore + SAS = Flexibility
While many professional solutions from Adaptec, ICP, LSI and other storage controller vendors have been limited to expensive SCSI drives, RAIDCore was the first vendor to pair enterprise class features with mainstream Serial ATA drives, offering excellent value. In this way, inexpensive and high-capacity storage arrays using SATA drives became possible, though SATA RAID was never capable of providing an alternative for high-performance applications, despite the availability of relatively fast hard drives such as the Western Digital Raptor or Raptor-X. The latest VelociRaptor is more likely to be used in SAS or enterprise-class environments.
Finally, professional storage controllers based on SCSI, and semi-professional entry-level solutions based on Serial ATA, have recently merged into the Unified Serial segment. This means that controllers may be positioned as entry-level, mainstream, or high-end solutions for businesses or enterprises, and they can be differentiated by aspects such as port count or features. However, both SAS and SATA are always supported and drives can even be mixed. This turns out to be a nice advantage for RAIDCore, as you can start with the VST Pro software using a motherboard SATA controller with a few ports, and seamlessly upgrade to a Unified Serial or SAS controller card later on.