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thegeezer <thegeezer@×××××××××.net> writes: |
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>> Guess what, I still haven't found out how to actually back up and |
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>> restore a VM residing in an LVM volume. I find it annoying that LVM |
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>> doesn't have any way of actually copying a LV. It could be so easy if |
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>> you could just do something like 'lvcopy lv_source |
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>> other_host:/backups/lv_source_backup' and 'lvrestore |
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>> other_host:/backups/lv_source_backup vg_target/lv_source' --- or store |
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>> the copy of the LV in a local file somewhere. |
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> |
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> agreed. you have two choices, you can either use dd and clone the LV |
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> like a normal partition. |
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> alternatively you can use split mirrors and i do this to clone up |
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> physical devices: |
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> |
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> 1. make a mirror of the lv you want to copy to /dev/usb1 |
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> 2. # lvconvert --splitmirrors 2 --name copy vg/lv /dev/usb1 |
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> |
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> in 2 it says |
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> " split the mirror into two parts |
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> give the new version the name 'copy' |
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> leave this on the pv /dev/usb1 " |
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> |
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> you then need to remove it if you want from your voume group |
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And then you have a copy? |
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>> Just why can't you? ZFS apparently can do such things --- yet what's |
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>> the difference in performance of ZFS compared to hardware raid? |
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>> Software raid with MD makes for quite a slowdown. |
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> sorry but that's just not true, if you choose the correct raid level and |
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> stripe it can easily compete, |
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|
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No, it can not. You can use the same raid level and stripe size with |
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the same disks, once with software raid (md), once with hardware raid. |
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When there's disk activity going on, you will notice an annoying |
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sluggishness with the software raid which hardware raid just doesn't |
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have. |
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> and be more portable (you don't have to find the identical raid card |
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> if the raid card goes bang); |
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That depends on what cards you use. HP smart arrays are supposed to be |
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compatible throughout different models. |
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> many raid card i would argue are even underpowered for their required |
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> iops |
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When you require more iops than your hardware delivers, you need to |
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upgrade the hardware. Do you have some number to show that md raid |
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performs better, without the sluggishness, than a decent hardware raid |
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controller with otherwise identical hardware? |
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-- |
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Again we must be afraid of speaking of daemons for fear that daemons |
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might swallow us. Finally, this fear has become reasonable. |
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