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Daniel Troeder <daniel@×××××××××.com> [14-05-17 16:36]: |
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> Am 17.05.2014 11:58, schrieb Neil Bothwick: |
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> > On Sat, 17 May 2014 09:59:08 +0200, meino.cramer@×××.de wrote: |
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> > |
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> >>> 3. Or you could use a sequential copy: |
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> >>> |
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> >>> cp -a /home /dev/sdb1/ && cp -a /home /dev/sdc1 |
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> > |
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> >> 3.) The files I want to copy are in the size of some GB each. So the |
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> >> cache isnt big enough to hold ALL files for the second part. |
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> > |
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> > Run the two copies simultaneously, start the first, switch to another |
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> > tab, start the second. That way the data for the second copy is always |
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> > the most recently cached. |
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> > |
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> > However, I expect the speed limit here may be the USB bus unless you are |
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> > using USB 3.0 drives on different buses. |
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> I was thinking about "how to make sure cache is used", and that two |
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> simultanious cp won't work, because the progress for the two cp will |
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> quickly diverge. But then I realized: there is no need to think about |
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> the read cache - the limiting factor is always the writing side, |
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> especially with USB! So IMO it doesn't matter at all how you do it! |
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> |
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> I guess two simultaneous cp will be the same as two sequential cp, |
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> except if you have two separate USB-buses. Usually you have just one |
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> externally connectible, use "lsusb -t" to check. |
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> |
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> If you have less that 2 times the size of your files, IMO simultaneous |
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> cp will be worse, because Linux (don't know if USB-subsystem or cp) |
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> creates big buffers when cp'ing (check with "free -m"), and you'll |
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> probably get into memory trouble. |
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> |
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> |
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> Greetings, |
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> Daniel |
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> |
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> PS: Quickest way is always to open USB-case and plug SATA cable from |
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> motherboard into drive. With >80GB it's always worth the trouble. |
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> |
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> -- |
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> Get my PGP key at: |
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> * |
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> http://keyserver.ubuntu.com:11371/pks/lookup?op=get&search=0x837FB8B5BB9D4887 |
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> * $ gpg --recv-keys --keyserver keyserver.ubuntu.com 0xBB9D4887 |
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> |
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|
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Hi, |
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|
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thank you /.*/ for /.*/ replies ! :) |
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|
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...one aspect is missing: The load (that is the I/O on the |
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source hd). |
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If this hd is busy spitting out the data twice, it cannot |
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serve outhe jobs twice as long... |
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|
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Hmmmm.... |
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|
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Best regards, |
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mcc |
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|
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PS: |
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On the source system |
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#> lsusb -t |
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/: Bus 09.Port 1: Dev 1, Class=root_hub, Driver=ohci-pci/4p, 12M |
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/: Bus 08.Port 1: Dev 1, Class=root_hub, Driver=ohci-pci/2p, 12M |
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/: Bus 07.Port 1: Dev 1, Class=root_hub, Driver=ohci-pci/5p, 12M |
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|__ Port 2: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M |
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|__ Port 2: Dev 2, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M |
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/: Bus 06.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M |
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/: Bus 05.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M |
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/: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=ohci-pci/5p, 12M |
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|__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M |
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|__ Port 3: Dev 3, If 0, Class=Audio, Driver=snd-usb-audio, 12M |
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|__ Port 3: Dev 3, If 1, Class=Audio, Driver=snd-usb-audio, 12M |
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/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/4p, 480M |
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/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/5p, 480M |
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/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/5p, 480M |
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|__ Port 4: Dev 4, If 0, Class=Hub, Driver=hub/6p, 480M |