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I wonder if JMB363 can support really full bandwidth of two SATA2 HDDs

  • NAS / RAID
  • Bandwidth
  • Support
  • Motherboards
  • PCI Express
  • Storage
Last response: in Storage
October 10, 2009 4:24:10 PM


SouthBridge of My motherboard is ICH8.

ICH8 doesn't support AHCI.

So, my motherboard has JMB363 storage controller.

JMB363 is a single chip, one-lane PCI Express to two-port SATA2 and one-port PATA Host Controller.

I connect four of my HDDs(two SATA2 and two IDE HDDs) to JMB363.

Bandwidth of one-lane PCI Express is 2.5Gbs. But, bandwidth of SATA2 is 3Gbs.

Theoretically, Full bandwidth of my four HDDs is 3+3+0.66+0.66 = 7.32 Gbs.

Surely, four HDDs hardly have an opportunity for Full speed operation simultaneously.

But, I think that one-lane PCI Express cannot cover the bandwidth of four Hdds.

Furthermore, can JMB363 handle I/O requests of four HDDs simultaneously?

I want to know about this.

Thank you.

More about : jmb363 support full bandwidth sata2 hdds

a c 127 G Storage
a b V Motherboard
October 10, 2009 8:07:01 PM

Bandwidth of what? You're confusing the interface (SATA 3Gbps) with the speed of the drive. IF each drive can do no more than 125MB/s, then two disks on a PCIe x1 would be fast enough - since this offers 250MB/s for PCIe x1 gen1 and 500MB/s for PCIe x1 gen2.

Besides i don't think you can use the PATA disks on the same RAID array. If you do, 4 devices on PCIe x1 is indeed a bottleneck. But likely you'll face other problems that cause you to not saturate the PCI-express interface.

The real question is how efficient the RAID-drivers are; and i can tell you Windows software RAID does a better job. So if you don't need boot support; i'd recommend software RAID0 instead.