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