I've always found USB very flaky. I've experienced lots of random freezes (needing hard resets) when for instance I accidentally unplug a drive before unmounting. Drives would only sometimes automatically mount and most of the time I had to manually told it to go ahead and mount. Drives would take very long to mount. It's always been a frustrating mess I found.Installing Xubuntu 15.04, it's gotten worse. I now can not at all mount my 4TB USB drive any more. It consistently totally freezes my system. The clock's seconds hand stops going. Caps-lock light doesn't respond anymore. Can't switch to a tty. It 100% freezes. Every time.Now, I could have a bad USB hub, because it is pretty much the cheapest I found through Ebay. It does USB 3.0 and never seems to work with USB 2.0 drives (it reverts to USB 1.1 then it seems).I also find USB 3 cables very badly designed. When you wriggle the connected plug a bit up and down, it immediately develops a bit of play room. I find the 3.0 plugs the kind of quality of crappy connectors one might find at a Dollar Store or something like that.I've had problem with multiple cables, multiple drives, and two hubs, and also directly without a hub, and two motherboards, over the years. There's always something up with the whole USB drive thing. Am I the only one that finds USB flaky (been for years, still not fixed)?Sorry if I'm not sounding very constructive here, but I'm very frustrated at this point. Again, I can't move my files from one drive to another, and again I can't put on home movies for visitors that stopped by our place. Again I'm let down by technology, and again it's USB.I'm willing to send/donate my USB hub if need be. Regardless of if/what hardware is flaky, if that's what it is, in my opinion, there is absolutely no excuse for a system to completely lock up. Getting errors is one thing, but things grinding to a halt is not right.I don't know where to start to diagnose this. I suppose copy pasting the last signs of life before the lock up would help...May 16 20:39:01 q kernel: [   51.797792] usb 2-1.3: new SuperSpeed USB device number 4 using xhci_hcdMay 16 20:39:01 q kernel: [   51.814128] usb 2-1.3: New USB device found, idVendor=0bc2, idProduct=3312May 16 20:39:01 q kernel: [   51.814131] usb 2-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3May 16 20:39:01 q kernel: [   51.814133] usb 2-1.3: Product: Expansion DeskMay 16 20:39:01 q kernel: [   51.814135] usb 2-1.3: Manufacturer: Seagate May 16 20:39:01 q kernel: [   51.814136] usb 2-1.3: SerialNumber: NA4N09H6May 16 20:39:01 q kernel: [   51.814858] scsi host8: uasMay 16 20:39:01 q kernel: [   51.815656] scsi 8:0:0:0: Direct-Access     Seagate  Expansion Desk   0739 PQ: 0 ANSI: 6May 16 20:39:01 q mtp-probe: checking bus 2, device 4: /sys/devices/pci0000:00/0000:00:07.0/0000:03:00.0/usb2/2-1/2-1.3May 16 20:39:01 q mtp-probe: bus: 2, device: 4 was not an MTP deviceMay 16 20:39:01 q kernel: [   51.816610] sd 8:0:0:0: Attached scsi generic sg4 type 0May 16 20:39:01 q kernel: [   51.867739] sd 8:0:0:0: [sdd] Spinning up disk...May 16 20:39:11 q kernel: [   57.292668] ......readyMay 16 20:39:11 q kernel: [   62.605638] sd 8:0:0:0: [sdd] 976754645 4096-byte logical blocks: (4.00 TB/3.63 TiB)May 16 20:39:11 q kernel: [   62.606455] sd 8:0:0:0: [sdd] Write Protect is offMay 16 20:39:11 q kernel: [   62.606459] sd 8:0:0:0: [sdd] Mode Sense: 2b 00 10 08May 16 20:39:11 q kernel: [   62.607310] sd 8:0:0:0: [sdd] Write cache: enabled, read cache: enabled, supports DPO and FUAMay 16 20:39:15 q kernel: [   65.771218] general protection fault: 0000 [#1] SMP May 16 20:39:15 q kernel: [   65.771233] Modules linked in: cfg80211 snd_hda_codec_hdmi joydev nouveau snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_seq_midi snd_seq_midi_event kvm_amd kvm serio_raw k10temp snd_rawmidi edac_core edac_mce_amd snd_pcm snd_seq mxm_wmi video snd_seq_device ttm snd_timer drm_kms_helper drm snd i2c_piix4 i2c_algo_bit soundcore shpchp wmi 8250_fintek mac_hid parport_pc ppdev lp parport autofs4 pata_acpi hid_generic usbhid hid uas usb_storage firewire_ohci psmouse firewire_core ahci crc_itu_t r8169 pata_atiixp libahci miiMay 16 20:39:15 q kernel: [   65.771303] CPU: 2 PID: 2424 Comm: panel-13-cpugra Not tainted 3.19.0-15-generic #15-UbuntuMay 16 20:39:15 q kernel: [   65.771309] Hardware name: Gigabyte Technology Co., Ltd. GA-MA770T-UD3P/GA-MA770T-UD3P, BIOS F7 04/14/2010May 16 20:39:15 q kernel: [   65.771315] task: ffff88041a5b09d0 ti: ffff88041c774000 task.ti: ffff88041c774000May 16 20:39:15 q kernel: [   65.771320] RIP: May 16 20:40:44 q rsyslogd: [origin software=rsyslogd swVersion=7.4.4 x-pid=735 x-info=http://www.rsyslog.com] start
4TB USB drive consistence totally freezes Xubuntu 15.04
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