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Boot from external HD? RRS feed

  • Question

  • I would like to try the beta, but without installing over vista.

    Can I install the OS beta to my external HD and use the BIOS to boot from it when I want to?

    If so, do I have to do anything special to install to a drive other than C:?

    Also, if I do this, will my external HD basically become the default HD for the beta?


    Thursday, February 5, 2009 7:05 PM

Answers

  •  

    To answer your question in a nutshell, yes.  You can load Windows 7 to an external hard drive provided your BIOS allows the operation.  However, there are some caveats.

    As Carey mentions, USB2 has a raw, theoretical max throughput of 480Mbps.  In real world usage, you may only get 60% to 70% of that; therefore, you would be looking at a useful throughput of 288Mbps to 336Mbps.   Compare this to an IDE throughput of 1.06Gbps (133MBps) and to SATAs 1.5Gbps and SATA-II 3.0Gbps.  You will take a tremendous I/O performance hit if you use a USB2 external drive.

    However, all is not lost.  If you have an eSATA connection, you can use an eSATA drive which will give you the native performance of the SATA interface with the benefits of an external drive.  Even if you don’t have an onboard eSATA interface, you can easily add one to your PCI (limited to 1.5Gbps SATA) or PCI-e (not speed limited) expansion slots.  However, using the latter solution and depending on the card manufacture, you may have to provide the controller drivers at installation time.

    Friday, February 6, 2009 4:28 AM

All replies

  • Hi

    All is posible, but what you call external hdd?

    To install set you external hdd as first boot HDD, before to start setup.

    Thursday, February 5, 2009 7:21 PM
  • Just to make sure I understand:
    1. During install, I select my USB HD as the boot drive.
    2. Then, when I reboot, if my HD is plugged in, it will boot from there, otherwise vista will boot normally from c:?
    3. Then, when I use the beta, my external will act like the C: drive?

    Thursday, February 5, 2009 7:25 PM
  • 1. Before to run setup set in bios dvd as 1 boot drive and your usb hdd as second boot drive, and internal hdd as 3 boot drive

    Thursday, February 5, 2009 8:26 PM
  • You cannot install Windows 7 beta on an external drive.  Most folks install Windows 7 on a second hard drive or an empty partition on their main hard drive.
    Carey Frisch
    Thursday, February 5, 2009 8:39 PM
    Moderator
  • External hard drives are  designed for file storage and backups only.  If you somehow managed to install an operating system on one, it would run extremely S_L_O_W.  Remember, USB 2.0 has a raw data rate of only 480Mbps.
    Carey Frisch
    Friday, February 6, 2009 3:34 AM
    Moderator
  •  

    To answer your question in a nutshell, yes.  You can load Windows 7 to an external hard drive provided your BIOS allows the operation.  However, there are some caveats.

    As Carey mentions, USB2 has a raw, theoretical max throughput of 480Mbps.  In real world usage, you may only get 60% to 70% of that; therefore, you would be looking at a useful throughput of 288Mbps to 336Mbps.   Compare this to an IDE throughput of 1.06Gbps (133MBps) and to SATAs 1.5Gbps and SATA-II 3.0Gbps.  You will take a tremendous I/O performance hit if you use a USB2 external drive.

    However, all is not lost.  If you have an eSATA connection, you can use an eSATA drive which will give you the native performance of the SATA interface with the benefits of an external drive.  Even if you don’t have an onboard eSATA interface, you can easily add one to your PCI (limited to 1.5Gbps SATA) or PCI-e (not speed limited) expansion slots.  However, using the latter solution and depending on the card manufacture, you may have to provide the controller drivers at installation time.

    Friday, February 6, 2009 4:28 AM
  • Thanks for the info.  I knew I would take a performance hit, but I was more interested in experimenting with Windows 7 features rather than the improved performance, as I would expect the performance to be better in the final anyways.

    Basically I wanted to try out the new OS without loosing my normal computer operation.
    Friday, February 6, 2009 5:54 AM