On Sun, 2 Jan 2011 09:18:19 +0100 "Niels Dettenbach" <nd%syndicat.com@localhost> wrote: > > is LVM backed DomU as fast as DomU on physical disk? > > LVM is typicaly faster then a file based disk image in XEN backend. > > Comparing phys and lvm is not a xen related question as this is not > part of xen / there is no real difference in how XEN handles it (both > handled by the phys: driver). > > As afaik lvm backends are the widest spreaden in productive XEN usage > and even typical in enterprise products i would assume that it is the > most tested constellation. > > Comparing LVM and physical performance of NetBSD is a thing byself > and there is no general answer in practice as it depends from a wide > range of factors i.e. underlying hardware (I/O-sys / > RAID-controller), the LVM-configuration, the "overlying" fs and - not > at least - your applications above. > > There are a lot of discussions around this topic in the net. > > Even if LVM could be thought as an additional "layer" between > filesystem and hardware most practical experiments or tests shown no > or a minimal only performance impact of LVM compared to a "straight" > hard disk. > > In case you run a high level storage system LVM might be not a help > in your situation anymore - so it might be that the possibly but > minimal impact of LVM weights harder then a null weighted comfort of > LVM in your situation. > > For reasons of comfortability LVM often should be the first choice - > especially (but not only) in the server area. Thank you for your detailed reply Niels. I was in two minds about LVM but you have persuaded me! However, it appears it's not in 5.1 so I will wait until 6.0 comes out. I am too new with NetBSD to try -current. :) -- Gerard Lally
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