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MB RAID Vs Dedicated Controller

  • Hard Drives
  • NAS / RAID
  • Controller
  • Storage
  • Product
Last response: in Storage
November 25, 2006 3:28:49 PM

Hi everyone, I checked the history but I couldn't find any previous discussion on the topic.

I know there's a huge difference between software and hardware RAID. I'm considering buidling a dual boot machine with 2x250 or 320 Go in RAID1 for protecting sensitive data. Is there really a need for a dedicated RAID controller or is the MB controller enough ? I mean, is there a real performance improvement ? And the price range for RAID cards ranges fron $60 to $400 for a PCI-Ex 2 ports RAID. What is the difference between them ?

I want to be able to use my RAID drives in both Win and Linux, I guess the drivers haev to be installed for both OS, and the drive ois not directly recognized as a single drive ?

Thanks in advance

More about : raid dedicated controller

November 26, 2006 12:07:51 AM

For RAID-0 and RAID-1 there is not much difference in the sustained transfer rate that can be obtained with motherboard controllers and dedicated RAID controllers. In fact, in some cases, the add-on RAID controller can have a lower sustained transfer rate because the card is interface-speed limited. (For example, 2 drives in a RAID-0 might theoretically be capable of transfer rates up to 150MB/sec, but if the controller is in a PCI slot, the PCI bus is limited to 90-120 MB/sec).

Now, a dedicated RAID controller will generally outperform the motherboard controllers in terms of I/O's per second (IOPs). Also, add-on RAID controllers frequently have large cache's which can reduce average latency.

The IOPs and latency are frequently more important as to how fast the disk subsystem "feels" than the sustained transfer rate. It also will improve boot times if the latency is lower.

Note again that all of the previous applies only to RAID-0 and RAID-1. RAID-5 is an entirely different matter, and requires heavy horsepower to increase write speed due to the XOR operation involved in computing parity. High-end RAID cards run circles around motherboard controllers in RAID-5.
November 26, 2006 5:38:34 AM

Hello an thank you very much

Yeah this is exactly the answer I was considering. I really need only RAID1 since all that matters is security, I'm gonna put all of my PhD work on it so... :-) Then it's mainly for storage, some latex, but also big file read/write (running heavy codes with >10Go outputs, lots of files - arounf 100000 each run), the latter being my main concern

Thus I was considering either a simple MB RAID1 chipset, or buying a more dedicated Areca 1120 PcI Express for 150 / 300 Mb/s transfer rate. I just don;t know if lower price card (around 75$) would do the same job....

One more time I don't know if I really need it, I just can't afford to lose data, and it would be good to have efficiency on file transfer...

OS will boot from separated Raptor, so boot time is not an issue

Anyway, thank you for your comments