On Tue, 23 Jun 2015 18:42:13 -0700 Gordon Messmer <gordon.messmer at gmail.com> wrote: > > I wondered the same thing, especially in the context of someone who > prefers virtual machines. LV-backed VMs have *dramatically* better > disk performance than file-backed VMs. Ok, you made me curious. Just how dramatic can it be? From where I'm sitting, a read/write to a disk takes the amount of time it takes, the hardware has a certain physical speed, regardless of the presence of LVM. What am I missing? For concreteness, let's say I have a guest machine, with a dedicated physical partition for it, on a single drive. Or, I have the same thing, only the dedicated partition is inside LVM. Why is there a performance difference, and how dramatic is it? If you convince me, I might just change my opinion about LVM. :-) Oh, and just please don't tell me that the load can be spread accross two or more harddrives, cutting the file access by a factor of two (or more). I can do that with raid, no need for LVM. Stick to a single harddrive scenario, please. Best, :-) Marko