Lshw In CentOS 7 Withdrawn

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More likely, crap hardware, which is awfully hard to avoid in USB-land.

Just the other day, I traced a machine that failed to reboot to an external USB disk. Unplug it, machine boots right up. Move the same disk to a machine as different as can be — different hardware, different OS, different firmware… — and it kernel panic’d that box within about a minute of plugging it in.

Then there was the time a USB enclosure ate my data. Only the filesystem’s strong checksums saved me that time. I moved the disk to another enclosure, and the bad sector writes stopped occurring; all else remained the same.

The problem is a market conditioned to believe that it should expect to pay $13.64 for an enclosure, power supply, and interface cable and get a 5-star product. If you put a $200 enclosure in front of the vast majority of members of that market, they’d either disbelieve the price or rate it 1 star for bad value, even if it was guaranteed to outlast the prevalence of the USB standard it supports, had a higher transfer rate, and had guaranteed data corruption rates best given in scientific notation with large negative exponents.

Whenever I have a machine with an unkillable userspace program, I run dtrace, and almost always get told exactly which bit of hardware (and therefore which kernel driver) is holding the machine hostage.

You might be able to dig the same info out of /var/log/messages, given close-enough timestamps.

3 thoughts on - Lshw In CentOS 7 Withdrawn

  • Sorry, got my OS wires crossed: I mean dmesg. Though dtrace could help, too, if you’ve managed to build that for CentOS; I hear it can be dnoe. :)

  • Warren Thanks for the thoughts. Even with ‘dmesg’, I
    found nothing. The reboot got rid of the problem and it continues to run perfectly in the same configuration.

    I, too, have a slight dislike for external USB
    disks, and much prefer internal drives for esveral reasons:
    – Internal drives are protected by being inside a tower and thus have less chance of falling or being bumped than free-standing external boxes
    – Fewer plugs and wires
    – Power-up sequencing is coordinated with CPU power
    – SATA3 is faster than USB3 (I think)

    But sometimes one has no choice. The Mac pro may look cute in its black cylinder, for example, but there’s no place to add anything to it. External drives are the only choice that I know of.


    At 07:57 AM 1/15/2018, Warren Young wrote:

  • Almost always, yes.

    Only if you have no PCI slots, and hence can’t put a better interface into the system.

    The old trashcan Mac Pro has *six* Thunderbolt 2 ports in 3 separate busses, running at a reliable 20 GBit/sec per bus. Contrast USB 3.0, which might deliver its promised 5 Gbit/sec on a perfect bench test with uncommonly good cabling and other hardware, and where there’s a fair chance you have only 1 or 2 busses per system, with the bandwidth shared among the ports on each bus.

    Much of the difference in quality between USB and Thunderbolt comes from the fact that Thunderbolt is almost exclusively found on professional-grade machines, so there isn’t as much drive behind the old race to the bottom, so that there actually are reliable Thunderbolt cables and enclosures available, and the vendors of same tend not to cheap out on things like power supplies.

    You won’t pay $13.64 for a Thunderbolt enclosure and cable, though.

    The same is true of other professional-grade storage busses like Fibre Channel. You gets what you pays for.

    Contrast eSATA, which I’ve found to be about as troublesome as USB, again due to a race to the bottom.