OT Hard Disk Geometry

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My only excuse for asking this question here is that I am running CentOS-6.5 on my HP MicroServer.

I recently purchased a 2TB WD hard drive (WD20ESRX), and was surprised to find that the power-connector on this drive did not seem to be in the correct place for the drive-bay.
(The drive bay closes, but the disk does not spin.)

The power connector on the drive is further from the SATA connectors than on the other 4 drives I have in my two MicroServers –
it is about 2/3 of the way across the back of the drive, on the opposite side to the SATA connectors.

I’m surprised because I always thought that the positions of the connectors on SATA hard drives was standard.

How can I find whether or not a hard drive will connect properly in the drive-bay?
Was I unlucky to choose a drive that did not fit?

16 thoughts on - OT Hard Disk Geometry

  • From where? A search on wdc.com says there is no such part number.

    Did you mean E*Z*RX?

    Can you take pictures of the drive, both sides, and post them for our perusal?

  • John R Pierce wrote:

    Sorry. That was a typo. The WD hard drive is: WD20EZRX (as suggested).

    That picture shows the WD drive above that I have. As you see, there is an empty (and slightly smaller) “slot”
    between the SATA connectors and the power connector.

    Now I’m looking at one of the drives that works in my HP SuperMicro drive-bay. This is the Seagate 250GB Barracuda drive (ST3250318AS)
    that came with the machine. In this the power connector(s) are in the same position as the empty slot above, although the slot is slightly wider. This is true of the other 3 drives in my 2 SuperMicros.

    (Unfortunately I cannot provide a photo at the moment, as both my Android phone and my camera are out of action.)

  • It seems to me that there’s some confusion on your part about what a SATA power connector is…

    The SATA edge connector is divided in two parts, a larger one and a narrower one. The narrower one is the signal, or data, connector. The larger one is the power connector.

    Some older drives also had an additional common Molex connector for power, for compatibility reasons, since at first only a few power supplies had the SATA power connector. Note that the Molex connector does not enable the hot-plugging and unplugging of SATA drives. This needs the 3.3V supply that only the SATA connector provides. As far as I
    can see, the ST3250318AS does not have such a connector.

    The manual for the ST3250318AS is here:

    http://www.seagate.com/staticfiles/support/disc/manuals/desktop/Barracuda%207200.12/100529369b.pdf

    On page 28 you can read about the SATA cables and connectors. The pins you refer to, which are not present on the WD at the same position, are NOT power connections, that is a jumper block as you can read on the first image of page 28. The manual states the following:

  • >> that I am running CentOS-6.5 on my HP MicroServer.

    Can you please tell us which exact model of MicroServer do you have?
    That way, it will be easier to help you.

  • Timothy Murphy wrote:

    I think I misunderstood the power connection to a SATA drive.

    Apparently, the Molex power-connector I was referring to
    (which is in a different place on different drives)
    is not used, power for the drive coming from one of the SATA connectors.

    So I must look for a different explanation why my new WD drive does not seem to be working.

  • Timothy Murphy wrote on Fri, 07 Feb 2014 23:40:24 +0000:

    That “power connector” is a jumper bay. As Miguel explains the two “L-
    shaped” things are what gets used for SATA (the short one is data, the long one is power). An old IDE drive would have had a Molex power connector on the right – where you see “nothing” now.

    BTw: you *do* realize that naming it “hard disk geometry” implies something very different to the reader?

    Kai

  • Miguel Medalha wrote:

    Thank you very much for your lucid explanation, which has clarified the issue greatly in my mind. I was indeed completely ignorant of the basic facts about SATA drives, since in my (limited) experience they simply worked when installed.

    The two HP MicroServers I have are both N36L models, 3 years old. I had better check if these do support SATA3 drives.

  • Usually with WD SATA II and III drives, if you jumper pins 5 and 6 it forces them to the previous SATA mode for controllers that are not compatible.

    On SATA II (3 Gb/s) drives they called it OPT1; on SATA III (6 Gb/s)
    drives they call it PHY mode. See the bottom of the page at http://wdc.custhelp.com/app/answers/detail/search/1/a_id/1679#jumper

    Note those drawings show molex connectors which, as far as I’m aware of, they have never installed on SATA III drives, but that does indicate you start counting from the ’empty’ space where molex connectors were mounted on EIDE, and on many SATA I (1.5 Gb/s) drives so people didn’t have to buy adapters for their power supplies.

  • Timothy Murphy wrote on Sat, 08 Feb 2014 13:28:18 +0000:

    That jumper bay usually allows for setting to slower speeds. There should have been a small leaflet with the drive explaining it.

    Kai

  • With some SATA drives the mode change can only be done by a software utility. Some of them don’t have jumpers at all.

  • The server’s manual recommends filling the drive bays in the 1,2,3,4 order. At this point, you should check the HP support page for the server, Look for controller firmware updates, BIOS updates, troubleshooting advice and so on.

    Did you try to connect the drive alone? If it is detected alone, you will have a clue there. Some drives don’t go along with some others when installed in the same pair of ports, for example.

    I would also suspect the cable. I have had more problems with SATA cables than I could expect.

    Also, the drive itself can be defective. I once received two new WD high end drives that couldn’t be detected by any controller and I had to return them. The new ones worked fine.

  • Miguel Medalha wrote:

    Thanks for all your help, and to the others who advised me.

    I found that the drive worked in the end –
    I’m not sure what did the trick, I sprayed the contacts with Contact Cleaner, changed the drive to a different bay, took the drive out of its tray and re-installed it using Torx screws
    (though I’m sure the last made no difference).

  • SuperMicro is OEMing for HP now?

    The 4 pins next to the SATA data connector on the Seagate drive are nonstandard. Their purpose is not documented in Seagate manual:
    http://goo.gl/t2lncu

    I doubt they are some kind of secondary power connector. Far more likely are a programming header, a debug port, an auxiliary feature output (e.g. drive activity LED), a configuration jumper…

    No need. The Newegg page shows the connectors clearly:

    http://www.newegg.com/Product/Product.aspx?Item=N82E16822148451

    If this is a standard SATA enclosure, only the two keyed edge connectors need to be used, as Kai says.