Slow backup

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aussie
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Joined: 2018/06/30 12:21:31

Slow backup

Post by aussie » 2019/10/30 06:04:30

Hello,

I have two identical machines except one is running Centos 6 and one running Centos 7. When copying small files to the backup disc Centos 7 slows down to 18 MB/sec while copying the identical files to the same backup disc on Centos 6 I get 62 MB/sec.

I tried a backup on a virtual machine running Centos 7 before the upgrading and it was slower, but thought it was due to the virtual machine overhead. After upgrading one of the machines, I now can definitely state it is slower.

Has anyone else experienced the same problem?

Aussie

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TrevorH
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Re: Slow backup

Post by TrevorH » 2019/10/30 09:30:37

How is the backup disk attached?
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aussie
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Re: Slow backup

Post by aussie » 2019/10/30 09:43:14

Hi TrevorH,

The backup disk is attached by USB 3.0
It is a 4TB Seagate drive.

Aussie

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TrevorH
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Re: Slow backup

Post by TrevorH » 2019/10/30 09:50:25

If you check dmesg, is it connecting as USB3. Or better, install usbutils and run lsusb.py and see what that tells you about the speed of that device connection.
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aussie
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Re: Slow backup

Post by aussie » 2019/10/30 12:03:15

Hi Trevor,

dmesg show lots of errors.
[177817.666333] ehci-pci 0000:05:01.2: port 3 resume error -19
[177817.692321] ehci-pci 0000:05:01.2: port 3 resume error -19
[177817.718319] ehci-pci 0000:05:01.2: port 3 resume error -19
[177817.718359] usb usb3-port3: connect-debounce failed
[177817.718384] ehci-pci 0000:05:01.2: port 4 resume error -19
[177817.920315] ehci-pci 0000:05:01.2: port 4 resume error -19
[177817.920338] usb usb3-port4: over-current condition
[177817.946313] ehci-pci 0000:05:01.2: port 4 resume error -19

dmesg on my Centos 6 system doesn't show over-current and it is the same drive.
I'm not sure what is going on!

I think I'll install Centos 6 over the Centos 7 system and see if I'm still getting errors. I don't know if I have a hardware problem or if it is the Centos 7 system.

Thanks for your suggestion
Aussie

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TrevorH
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Re: Slow backup

Post by TrevorH » 2019/10/30 13:03:24

Two things from that spring out: first it's using ehci not xhci so it's USB 2 not USB 3.

The over-current thing, I'd try sticking it behind a powered USB hub and see if that helps.
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aussie
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Re: Slow backup

Post by aussie » 2019/11/05 06:49:50

Hi TrevorH,

I was worried about the backup with all the errors displayed by dmesg. But I verified using sha256sum and the backup is fine.
I is any wonder why the backup is slow, using the USB2 driver instead the the USB3 driver. I tried lsusb.py and it hangs and has to be aborted. But lsusb and lsusb -t work fine. I have 2 USB3 ports from the motherboard and 2 USB3 ports from a pci-e card plugged into the motherboard. These look like bus 7 and bus 9 from the lsusb listings. It has xhci as the driver for both the motherboard usb and the card usb, so I don't know why it is using the ehci driver. I have included listings from lsusb.

Code: Select all

lsusb -t
/:  Bus 09.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M
    |__ Port 2: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
/:  Bus 08.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
/:  Bus 07.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M
/:  Bus 06.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
/:  Bus 05.Port 1: Dev 1, Class=root_hub, Driver=ohci-pci/2p, 12M
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=ohci-pci/3p, 12M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/5p, 480M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
        |__ Port 2: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M
        |__ Port 5: Dev 3, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 5: Dev 3, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 6: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
lsusb
Bus 002 Device 003: ID 14cd:168a Super Top 
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 009 Device 003: ID 1058:0748 Western Digital Technologies, Inc. My Passport (WDBKXH, WDBY8L)
Bus 009 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 007 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 006 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 004: ID 1c4f:0048 SiGma Micro 
Bus 001 Device 003: ID 046d:c31c Logitech, Inc. Keyboard K120
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
BTW lsusb.py completes normally on Centos 6, but hangs and has to be aborted on Centos 7.

Aussie

aussie
Posts: 29
Joined: 2018/06/30 12:21:31

Re: Slow backup

Post by aussie » 2019/11/14 00:02:30

Hello,

I have had a breakthrough. All the errors messages in dmesg happen after the machine is resumed from a suspend. If the machine is booted from scratch there are no error messages in dmesg. Including the over-current condition.

I discovered this basically by accident when I upgraded my second computer to Centos 7. After the upgrade of the second machine I did a dmesg and there were no error messages. I thought the first machine must have a hardware problem. Today I did a dmesg on the second machine and it too had error messages. So I thought over what was different. I did a suspend last night and resumed out of the suspend this morning. I tried it and this is the problem.

Problem solved: I was thinking about the errors in dmesg and it was listing USB port 5. I have an Adaptec, 5 port USB2 card. It is a PCI card. I removed this card and all the errors are gone. Centos 6 never had a problem with this card, so it must be change in the driver. I'll submit a defect.

Aussie

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