SB850 Ma Dive Size


I just had a computer built for me that has an Asus M487TD Pro mother board. That motherboard uses the SB850 chipset and I am having a problem with it. I had the machine maxed out with 6 3T Hitachi drives but sometimes the motherboard recognizes these drives and sometime it doesn't. Even when it does, when I try to create a RAID 5 array in the BIOS, it tells me that the drives are a bit over 800G in size, not 3T.

My question is: Is 3T beyond the capacity of the SB850 chipset? Has anyone successfully used 3T drives either as single boot drives or in a RAID array?

Thnaks for any help on this.
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  1. I may be introducing a red herring, but FWIW AMD's SB850 southbridge has problems with certain Samsung HDDs.

    As for the capacity problem, it does appear to be a 2TiB limitation problem:

    3TB - 2TiB = (3 x (10^12)) - (2 x (1 024^4)) = 800 976 744 448
  2. I don't think that is a red herring at all -- I suspect that you have hit the nail on the head. Now I just have to figure a way out of this mess :-) Any idea what mother board will support 3T drives and an AMD AM3 CPU?

  3. Sorry, I haven't looked at a new motherboard for several years now. That's something for other members to suggest.

    That said, I would investigate any BIOS update options before opting for a new motherboard.
  4. That's possible but remember that this is a new build. Everything's brand new so I would assume that if the BIOS isn't the absolute latest, it should be pretty close.
  5. I am beginning to suspect the chipset here. After the disappointment with the 3T drives, the builder replaced the drives with 2T units, created a RAID 5 array and partitioned the array to have a 500G system drive and the rest as a data drive. I ran into problems with that because the array presented the larger disk as having 4K sectors and a lot of software (HyperV included) cannot tolerate 4K sectors. But, I noticed that a) the 500G drive presented itself with 512Byte sectors and b) I checked the disks and they have 512Byte sectors. So, the only thing I can figure is that the SB850 chipset must repackage the data for large drives in 4K sectors. Does that sound reasonable? I know that it blows me out of the water because all of the software I want to run on that box will only accept 512Byte sectors.
  6. I don't have any significant RAID knowledge or experience, but ISTM that the RAID controller's firmware (ie RAID BIOS) would be doing the repackaging. I doubt that it would be happening at the hardware level within the chipset.

    FWIW, I know that some external 3TB HDDs (eg Seagate 3TB GoFlex) present a 4KB LBA size via USB, even though the drive itself reports an LBA size of 512 bytes. In the GoFlex case the USB-SATA bridge chip handles the translation. I believe Seagate chooses to do it this way in order to support Windows XP straight out of the box.

    Have you checked the configuration options in your RAID BIOS?
  7. It is almost definately the RAID chipset. When I first started this thread, I was configuring the RAID with 2 drives: one 500G and one 9.5T (6 2T drives in the array). Both drives were RAID 5 and they spanned all 6 drives. When I installed Windows, it saw the 500G drive as having 512 Byte sectors and the 9.5T drive as having 4K sectors. Since that configuration was no good for me, I changed the RAID to have the first 2 drives mirrored and the last 4 configured as RAID 5. After installing Windows, I checked and found the 2T mirrored drive had 512 Byte sectors and the larger drive had 2K sectors.

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