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I recently purchased a 4-bay enclosure (Mediasonic Probox -- maybe cheap junk, but should work) with 4 2TB disks. The enclosure has both USB3 and eSATA interfaces. I originally intended to use it on USB3, but I had some trouble with that, so now I'm trying to use it with eSATA. Note that this box has no internal RAID of any kind. It is supposed to present the installed disks as individual disks.

The problem I'm having is that the Linux kernel only sees one of the 4 disks. I'm connecting it to the onboard ports of an Intel DX58SO motherboard, whose manual claims that, "They can also be used for port replication, which allows the aggregation of multiple hard drives on each of the eSATA ports."

I'm running Arch Linux, with kernel version I am able to access one of the disks as /dev/sda (which caused its own set of problems at boot time -- it displaced my internal disks upwards by one slot), but the other three are missing entirely.

Is there something special I need to do to make Linux see the multiplier?

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A couple of variables need to be answered prior to being able to answer your question intelligently. 1. What RAID type is the mediasonic box serving over the eSATA? 2. You are able to see /dev/sda which would be the first disk, what is the reported size of this disk? – tagram Aug 18 '11 at 23:30
There is no raid. It's a really stupid $140 box, and it's not supposed to do any kind of raid. The reported size (in fdisk) is 2000.4 GB, which is the size of the individual disks. Kernel says "3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB)" – Rick Koshi Aug 19 '11 at 5:26

The kernel option is CONFIG_SATA_PMP=y
Not sure if Arch has that in its default kernel.

However, tagram's line of questioning may be correct.
It's possible your enclosure is making a raid (or JBOD) array of your disks. This will present as a single disk. Sizes will be different than a single disk unless it's making a more than 2 disk raid1.

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According to /proc/config.gz, CONFIG_SATA_PMP is set to "y" – Rick Koshi Aug 19 '11 at 5:28
up vote 0 down vote accepted

In the end, I decided the box was a cheap piece of garbage. I thought I might have received a faulty unit, so I did an RMA and got a replacement. The new unit behaved in exactly the same way, including the many USB I/O errors not documented here.

It's still possible that I was doing something wrong, since it's suspicious that I received two units that failed in exactly the same way, but it's also possible that the designers didn't do sufficient compatibility testing, and that it just can never work with my hardware (I also tried it on a different box running Windows with the same motherboard, and got the same results).

In any case, I sent the unit back. I've ordered a completely different unit from a different manufacturer, and hopefully that will work out better.

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Is the eSATA device from the different manufacturer trouble-free on your two computers, Linux and Windows? – Graham Perrin Oct 18 '12 at 3:32

Sorry to necro this old question, but my guess is that your motherboard only supports port multiplier when the BIOS is set to AHCI. Most motherboards are that way, if they support port replication at all. You can always get an add-in card for $30 - $60.

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Hm. Possible. I can't test it now, of course, since the box is long gone. In the end, bandwidth limitations actually meant it was better to dedicate a USB3 interface to each disk, using a separate enclosure for each. Sounds silly, but the math backs it up. – Rick Koshi Feb 11 '12 at 10:53

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