Upgrading a RAID system - Storage

This is a discussion on Upgrading a RAID system - Storage ; Dear all, I'm a newbie on the RAID system. I just read something on wiki and on other website. Since my external USB HD is getting full, I wanted to integrate it with a NAS. Let's assume I buy a ...

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Thread: Upgrading a RAID system

  1. Upgrading a RAID system

    Dear all, I'm a newbie on the RAID system. I just read something on
    wiki and on other website.
    Since my external USB HD is getting full, I wanted to integrate it
    with a NAS.
    Let's assume I buy a 4 bays NAS with 2 500 GB HD mounted. Then I will
    add an old 180 GB HD.
    Now the questions:

    1) Can I create 2 volumes (if volume is the right word) one 3x180 GB
    RAID 5 for 360 GB of space (more or less) and the other 2x320 GB RAID
    1/5 for additional 320 GB (Total 680 GB out of 1180)?

    2) If later I add a 4th HD, for example a 750 GB HD, can I upgrade the
    system without losing data and without doing any external backup to a
    2 volumes systems with one 4x180 GB RAID 5 for 540 GB of space and the
    other 3x320 GB RAID 5 for additional 640 GB and eventually a volume
    single HD of 250 GB (TOTAL 1430 GB out of 1930)

    3) If later I substitute the smallest HD with a 750 GB HD, can I
    upgrade the system without losing data and without doing any external
    backup to a 3 volumes systems with one 4x180 GB RAID 5 for 540 GB of
    space, one 4 x320 GB RAID 5 for additional 960 GB and the other 2x250
    for additional 250 GB (TOTAL 1750 GB out of 2500)

    If yes for all the questions, which NAS on the market allow me to do
    this upgrade friendly?

    Thanks a lot and sorry for the long message
    Bye MAO

    --
    MAO webmind@occupato.it (liberami x scrivermi)
    www.riolab.org
    "i troni sono stati creati per innalzare gli idioti" (KINA)
    --

  2. Re: Upgrading a RAID system

    Previously Mao wrote:
    > Dear all, I'm a newbie on the RAID system. I just read something on
    > wiki and on other website.
    > Since my external USB HD is getting full, I wanted to integrate it
    > with a NAS.
    > Let's assume I buy a 4 bays NAS with 2 500 GB HD mounted. Then I will
    > add an old 180 GB HD.


    > Now the questions:


    > 1) Can I create 2 volumes (if volume is the right word) one 3x180 GB
    > RAID 5 for 360 GB of space (more or less) and the other 2x320 GB RAID
    > 1/5 for additional 320 GB (Total 680 GB out of 1180)?


    If it is Linux software-RAID based an you do not fear partitioning
    and configuring the RAID arrays yourself, this is possible and I have
    done similar things in the past. The trick is not to use full
    disks as basis, but partitions. Linux software RAID supports that.
    Out of the box or with a hardware controller, you can typically
    only do full-disk RAID.


    > 2) If later I add a 4th HD, for example a 750 GB HD, can I upgrade the
    > system without losing data and without doing any external backup to a
    > 2 volumes systems with one 4x180 GB RAID 5 for 540 GB of space and the
    > other 3x320 GB RAID 5 for additional 640 GB and eventually a volume
    > single HD of 250 GB (TOTAL 1430 GB out of 1930)


    Very likely not. The problem is not only extending the RAID array
    (again Linux software RAID with a modern kernel can do it), but you
    also need to extend the filesystem, which I think does currently not
    work even under Linux.

    > 3) If later I substitute the smallest HD with a 750 GB HD, can I
    > upgrade the system without losing data and without doing any external
    > backup to a 3 volumes systems with one 4x180 GB RAID 5 for 540 GB of
    > space, one 4 x320 GB RAID 5 for additional 960 GB and the other 2x250
    > for additional 250 GB (TOTAL 1750 GB out of 2500)


    See above.

    > If yes for all the questions, which NAS on the market allow me to do
    > this upgrade friendly?


    Out of the box: None. The Linux software-RAID based ones have
    more flexibility, but you would have to use the ordinary RAID
    management tools (mdadm).

    I suggest you read up on Linux software RAID to get an idea
    of what is involved.

    > Thanks a lot and sorry for the long message


    No problem. You should realize, that while from a user's
    POV your expectations are entirely reasonable, the technology
    is not there or only partially there.

    Arno


  3. Re: Upgrading a RAID system

    On 28 Feb 2008 03:40:39 GMT, Arno Wagner wrote:

    >> 1) Can I create 2 volumes (if volume is the right word) one 3x180 GB
    >> RAID 5 for 360 GB of space (more or less) and the other 2x320 GB RAID
    >> 1/5 for additional 320 GB (Total 680 GB out of 1180)?

    >
    >If it is Linux software-RAID based an you do not fear partitioning
    >and configuring the RAID arrays yourself, this is possible and I have
    >done similar things in the past. The trick is not to use full
    >disks as basis, but partitions. Linux software RAID supports that.
    >Out of the box or with a hardware controller, you can typically
    >only do full-disk RAID.


    That's good. I also read that flex-raid technology in RND4250 could
    allow this operation

    >> 2) If later I add a 4th HD, for example a 750 GB HD, can I upgrade the
    >> system without losing data and without doing any external backup to a
    >> 2 volumes systems with one 4x180 GB RAID 5 for 540 GB of space and the
    >> other 3x320 GB RAID 5 for additional 640 GB and eventually a volume
    >> single HD of 250 GB (TOTAL 1430 GB out of 1930)

    >
    >Very likely not. The problem is not only extending the RAID array
    >(again Linux software RAID with a modern kernel can do it), but you
    >also need to extend the filesystem, which I think does currently not
    >work even under Linux.


    That's strange. I thought if I had an HD with only 0, the parity still
    hold if I pass from 3x180 to 4x180. Then the controller could fill the
    forth HD with data and update the parity.

    I will have a look at linux RAID software...
    So maybe it's better to start with a 2x500 and then upgrade the system
    with other 500 GB HD (with x-raid on RND4250). The problem then is
    that if I want to extend capacity I have to substitute all the four
    HD.

    Do you think with Windows home server could be a better solution?

    My needs are
    - 300+ capacity for picture, mp3 etc where I want redundacy
    - backup of 2 laptop documents (100 GB each) where I don't need
    redundancy since I have one copy on the laptop and another on the NAS

    Thanks Maurizio
    --
    MAO webmind@occupato.it (liberami x scrivermi)
    www.riolab.org
    "i troni sono stati creati per innalzare gli idioti" (KINA)
    --

  4. Re: Upgrading a RAID system

    Previously Mao wrote:
    > On 28 Feb 2008 03:40:39 GMT, Arno Wagner wrote:


    >>> 1) Can I create 2 volumes (if volume is the right word) one 3x180 GB
    >>> RAID 5 for 360 GB of space (more or less) and the other 2x320 GB RAID
    >>> 1/5 for additional 320 GB (Total 680 GB out of 1180)?

    >>
    >>If it is Linux software-RAID based an you do not fear partitioning
    >>and configuring the RAID arrays yourself, this is possible and I have
    >>done similar things in the past. The trick is not to use full
    >>disks as basis, but partitions. Linux software RAID supports that.
    >>Out of the box or with a hardware controller, you can typically
    >>only do full-disk RAID.


    > That's good. I also read that flex-raid technology in RND4250 could
    > allow this operation


    >>> 2) If later I add a 4th HD, for example a 750 GB HD, can I upgrade the
    >>> system without losing data and without doing any external backup to a
    >>> 2 volumes systems with one 4x180 GB RAID 5 for 540 GB of space and the
    >>> other 3x320 GB RAID 5 for additional 640 GB and eventually a volume
    >>> single HD of 250 GB (TOTAL 1430 GB out of 1930)

    >>
    >>Very likely not. The problem is not only extending the RAID array
    >>(again Linux software RAID with a modern kernel can do it), but you
    >>also need to extend the filesystem, which I think does currently not
    >>work even under Linux.


    > That's strange. I thought if I had an HD with only 0, the parity still
    > hold if I pass from 3x180 to 4x180. Then the controller could fill the
    > forth HD with data and update the parity.


    That is possible for some RAID solutions. But your partition size and
    the filesystem in the partition will not get extended, and you end up
    with just 180GB empty space at the end of the RAID array.

    > I will have a look at linux RAID software...
    > So maybe it's better to start with a 2x500 and then upgrade the system
    > with other 500 GB HD (with x-raid on RND4250). The problem then is
    > that if I want to extend capacity I have to substitute all the four
    > HD.


    And you still have to adjust the pratitioning and filesystem sizes.

    > Do you think with Windows home server could be a better solution?


    No.

    > My needs are
    > - 300+ capacity for picture, mp3 etc where I want redundacy
    > - backup of 2 laptop documents (100 GB each) where I don't need
    > redundancy since I have one copy on the laptop and another on the NAS


    Extending RAID arrays really is more of an art today. I suggest you
    plan something that will keep for some time and in the future
    get something larger. E.g a 2x1TB RAID1 would probably keep
    for 3 years or so for you. Then in 3 years you can get an additional
    one.

    Arno

  5. Re: Upgrading a RAID system

    On 29 Feb 2008 15:40:58 GMT, Arno Wagner wrote:

    >> My needs are
    >> - 300+ capacity for picture, mp3 etc where I want redundacy
    >> - backup of 2 laptop documents (100 GB each) where I don't need
    >> redundancy since I have one copy on the laptop and another on the NAS

    >
    >Extending RAID arrays really is more of an art today. I suggest you
    >plan something that will keep for some time and in the future
    >get something larger. E.g a 2x1TB RAID1 would probably keep
    >for 3 years or so for you. Then in 3 years you can get an additional
    >one.


    Thanks a lot

    Bye Maurizio
    --
    MAO webmind@occupato.it (liberami x scrivermi)
    Vuoi scoprire il risolutore di excel: http://www.riolab.org/viewrisorsa.asp?id=115
    "i troni sono stati creati per innalzare gli idioti" (KINA)
    --

  6. Re: Upgrading a RAID system


    >Extending RAID arrays really is more of an art today.


    You might read up on ZFS & RAIDZ. It's kicking ass in a number of areas.



    I suspect you'd need to use it a networked file server, or run M$ as a
    virtual machine.
    --
    A host is a host from coast to coast.................wb8foz@nrk.com
    & no one will talk to a host that's close........[v].(301) 56-LINUX
    Unless the host (that isn't close).........................pob 1433
    is busy, hung or dead....................................20915-1433

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