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I'm looking for Magical Wonder Volumes. I want to be able to add a physical drive to an existing filesystem, and PRESTO! That filesystem has more storage and/or redundancy. When ...
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  1. #1
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    Question Configure LVM as mirrored AND linear?


    I'm looking for Magical Wonder Volumes.
    I want to be able to add a physical drive to an existing filesystem, and PRESTO! That filesystem has more storage and/or redundancy. When one of the physical drives eventually fail, no problem, Iíve lost some redundancy, I just have to install a new drive before another one fails.
    Letís assume I have 4 physical drives.
    Please, *What Is This Configuration? *

    Iíve read http://docs.redhat.com/docs/en-US/Re...ion/index.html

    But I am unclear if I can make a logical volume that is mirrored and linear.
    Thank you so much

    BTW
    The last time I tried software RAID 1 (dm-x) under lvm, it was very fragile. Systemd could not start it, and then an update to mdadm put a stake through its heart. So I know that does not work.
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  2. #2
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    Systemd could not start it, and then an update to mdadm put a stake through its heart. So I know that does not work.
    Yes, it does. An example here of live-migrating an LVM stripe to RAID1+0 using LVM + mdadm. You can mirror with LVM or you can stripe with LVM - I don't believe you can do both, which is why solutions almost always include mdadm + LVM.

  3. #3
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    Thanks, I'll give it another shot.
    But for other's info, there is currently a bug in LVM:and a bug in mdadm that interact terribly with systemD(isater). AFAIK, such a system cannot be auto-mounted at boot time, on Fedora 15 and later.

  4. #4
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    AFAIK, such a system cannot be auto-mounted at boot time, on Fedora 15 and later.
    No, the bug reports show:

    1. LVM = Disable lvm2-monitor (if you really *need* that, then don't use Fedora 15 at this time.)
    2. mdadm = Don't install the latest 2.6.40 kernel (bleeding edge means bleeding edge bugs.) It's already a known issue upstream that is expected to be resolved soon.

    Fedora is typically bleeding edge (at least for the last several releases) and these are the type of issues you can expect to find. There are many other stable distro's. Fedora 14 would be another possible solution.

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