Because my local RAID-based logical volume is not big enough, I am thinking to extend it to a network block device. I am aware that when read/write to the network block device, the performance is lower. However, the bigger risky thing: in cases of network instability, the data in this network-spanning volume may be corrupted. So my question is, how robust is LVM to deal with this setup? What other suggestions do you have?
SnapOverflow
You need all the pvs of a volume group, unless some of them are mirrors of each other.
Keeping the disks in a vg as similar as possible, such as all being local disk, is easier to manage.
You can extend a volume group onto new bigger disks of some kind, move the volumes to the new disks, and reduce the vg by the old disk.