Can I software RAID 1 two external (USB) hard drives? - Hardware

This is a discussion on Can I software RAID 1 two external (USB) hard drives? - Hardware ; Hi, I can't afford an external housing with built in RAID, so will accept software based RAID. I have an external housing, connected by USB, containing two identical hard drives. Can I make them appear as one, by using RAID ...

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Thread: Can I software RAID 1 two external (USB) hard drives?

  1. Can I software RAID 1 two external (USB) hard drives?

    Hi,

    I can't afford an external housing with built in RAID, so will
    accept software based RAID.

    I have an external housing, connected by USB, containing two identical
    hard drives.

    Can I make them appear as one, by using RAID 1 (mirror) in software?

    If so, how?

    Thanks in advance for any help.

  2. Re: Can I software RAID 1 two external (USB) hard drives?

    On Jan 25, 2:55*pm, Baron Samedi wrote:
    > Hi,
    >
    > * I can't afford an external housing with built in RAID, so will
    > accept software based RAID.
    >
    > I have an external housing, connected by USB, containing two identical
    > hard drives.
    >
    > Can I make them appear as one, by using RAID 1 (mirror) in software?
    >
    > If so, how?
    >
    > Thanks in advance for any help.


    Errm, they are SATA, if taht makes any difference.

  3. Re: Can I software RAID 1 two external (USB) hard drives?

    Baron Samedi writes:
    > I can't afford an external housing with built in RAID, so will
    >accept software based RAID.
    >
    >I have an external housing, connected by USB, containing two identical
    >hard drives.
    >
    >Can I make them appear as one, by using RAID 1 (mirror) in software?


    If you see each drive as a separate device (which is probably the
    case), then yes, you can.

    >If so, how?


    With mdadm, or with the installation software of your distribution.
    You will typically partition the drives in the same fashion, and then
    combine each pair of partitions into a RAID1.

    Note that with this setup, performance won't be great, especially for
    writes: On writes all the data has to go through the USB twice, and
    the fastest transfer rates I have seen through USB are around 30MB/s.

    - anton
    --
    M. Anton Ertl Some things have to be seen to be believed
    anton@mips.complang.tuwien.ac.at Most things have to be believed to be seen
    http://www.complang.tuwien.ac.at/anton/home.html

  4. Re: Can I software RAID 1 two external (USB) hard drives?

    On Jan 25, 8:45*pm, an...@mips.complang.tuwien.ac.at (Anton Ertl)
    wrote:
    > Baron Samedi writes:
    > > *I can't afford an external housing with built in RAID, so will
    > >accept software based RAID.

    >
    > >I have an external housing, connected by USB, containing two identical
    > >hard drives.

    >
    > >Can I make them appear as one, by using RAID 1 (mirror) in software?

    >
    > If you see each drive as a separate device (which is probably the
    > case), then yes, you can.
    >
    > >If so, how?

    >
    > With mdadm, or with the installation software of your distribution.
    > You will typically partition the drives in the same fashion, and then
    > combine each pair of partitions into a RAID1.
    >
    > Note that with this setup, performance won't be great, especially for
    > writes: On writes all the data has to go through the USB twice, and
    > the fastest transfer rates I have seen through USB are around 30MB/s.
    >
    > - anton
    > --
    > M. Anton Ertl * * * * * * * * * *Some things have to be seen to be believed
    > an...@mips.complang.tuwien.ac.at Most things have to be believed to be seenhttp://www.complang.tuwien.ac.at/anton/home.html



    Thanks for the info, that sounds like what I want.

    I'm not too concerned about slow write, as this is mostly photos, with
    the odd movie and maybe a little MP3. Wrtie is only once, intially,
    it's not like they are data fiels that are regularly opened and
    updated.

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