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RAID Problems With Intel Core 2?

Posted by ryuzaki0 on from the arr-aye-eye-dee dept.

Nom du Keyboard writes "The Inquirer is reporting that the new Intel Core 2 processors Woodcrest and Conroe are suffering badly when running RAID 5 disk arrays, even when using non-Intel controllers. Can Intel afford to make a misstep now with even in the small subset of users running RAID 5 systems?" From the article: "The performance in benchmarks is there, but the performance in real world isn't. While synthetic benchmarks will do the thing and show RAID5-worthy results, CPU utilization will go through the roof no matter what CPU is used, and the hiccups will occur every now and then. It remains to be seen whether this can be fixed via BIOS or micro-code update."

4 of 284 comments (clear)

  1. Re:These are the cheesy RAID cards, right? by amorsen · · Score: 4, Informative

    Software RAID is faster and more reliable than hardware RAID. Should your non-RAID controller fail, you just chuck it and get a random new one. If your RAID-controller fails, you have to get another controller exactly the same, sometimes even the same firmware revision, or kiss your data goodbye. And RAID-controllers are notoriously underpowered (SmartArray, I'm looking at you!)

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  2. Re:These are the cheesy RAID cards, right? by InsaneGeek · · Score: 3, Informative

    Software is more reliable+performance, what are you smoking? To get the performance you've got to turn on write caching, system goes down with write caching you're very likely (almost guaranteed) to have a corrupt filesystem. To get the reliability you turn off write caching, and performance plumments. Any hardware raid worth more than 3 cents has battery backed cache that allows you to have write caching and maintain reliability, not even taking in account being able to do some Raid5 operations with only 1 disk iop.

  3. XOR is very common by HaeMaker · · Score: 3, Informative

    You use XOR to clear a register. XOR CX, CX sets the CX register to 0. It is faster than MOV CX, 0.

  4. Re:Why aren't you running a dedicated controller.. by drsmithy · · Score: 5, Informative
    That's because you can do RAID 0, 1 or any combination of 0 and 1 without needing parity data. The performance killer on RAID 5 (and any other form of RAID that requires parity) is in the XOR operations used to compute and verify the parity information. In order for RAID 5 to perform at a satisfactory rate and not totally bog down your CPU, the XOR calculations should be handled on a dedicated hardware controller, not in software.

    No, no, no, no. The processing overhead of parity calculations is miniscule on any remotely modern CPU (even a paltry 300Mhz Pentium 2 has a parity throughput of ~700M/sec).

    The performance killer on parity-based RAID configuration is the additional disk reads required to calculate the parity, *not* the parity calculations themselves. Which is why modern software RAID is typically faster than hardware RAID until you get into larges numbers of disks and/or machines with limited bus bandwidth.

    This "RAID 5 is slow because of parity calculations" meme must die (although, admittedly, it's a good indicator of whether or not someone really understands what's going on).