Didn't see this in the FAQ

[LordWolf]

I even looked at the link for "which is better" between software and hardware RAID.

After looking through some RAID cards on NewEgg, I've noticed that not all of the cards handle the RAID processing directly, but instead offload the work to the computers CPU. I've seen this referred to as being a software based RAID card.

One such card is a RocketRAID 2640x4 card. I'm trying to learn how to tell the difference between a card that does all the work itself (true hardware RAID) and one that offloads some of the processing (software/fakeraid). If the description says that it's a hardware based RAID controller, then that makes it simple. However just because it doesn't say it, it doesn't mean it's not a hardware based RAID controller.

I've tried asking on Yahoo! Answers, and this dummy insists that a RAID controller is hardware based (even the RocketRAID 2640x4 card) and that the other kind (software/fakeraid) is only when it's built into the mobo. If this were the case, then there wouldn't be a concern about what kind of a card it is because they'd all do their own processing instead of offloading any of it to the computers CPU.

So, are there any tell-tale signs for the different types of cards? Is it a general rule of thumb that if it's not claimed to be a hardware based card that it means it's software based or are there enough that don't mention it to warrant further investigating or knowledge?

 

[mavroxur]

Software RAID refers to RAID arrays that are built and managed inside the operating system and do not use a hardware RAID controller. Any computer can use software RAID, provided the operating system supports it and you have met the prerequisite number of disks for the type of RAID you choose to implement.

Hardware RAID refers to a RAID array managed a seperate hardware-based controller (either onboard or on an expansion card). The card you mention in the original post is, in fact, a hardware RAID card.

Not all hardware RAID solutions are equal. When doing general mirroring and striping, the playing field is somewhat leveled in terms of performance. When you move to RAID 5, 50, 6, or 60, that's where the boys are seperated from the men. Cards that don't have a good parity calculation engine (weather it's a RISC processor or ASIC of some sort) and caching on the card will suffer greatly compared to a *good* RAID card that has these features. The reason being the extensive calculations required to generate parity data for these kinds of arrays.


Other features that sets apart cheap and good RAID cards are features like hot swapping, online array management, and online array rebuilding/migration. For the average joe, hot swap and online manage, rebuild, and migration might not matter, as they're more important in the commercial / enterprise segment.