On Sunday 07 October 2007, Florian Philipp wrote: > Philip Webb schrieb: > > Does anyone have advice based on experience using LVM ?
<snip> > Simple pros and cons? > > Pro: <snip> > - You loose bit performance, but not much, you won't feel it without > benchmarks. I very much doubt this. LVM is one extra layer between the filesystem and the physical disk and it basically consists of a mapping between the extents in the VG and exactly where they are on the volume. This is nothing more than an elementary lookup table; on a 500G VG using 32M extents this consists of precisely 15,625 entries, it can all be stored in RAM and can consist of one pointer plus precisely one calculation to determine the offset from the start of the table where the desired extent lies. Considering that RAM runs at many orders of magnitude faster than the disk you are trying to get the data off of, the extra fraction of a % overhead is not even worth trying to measure, let alone benchmark it. Moving the heads just once more because of file fragmentation probably takes longer than the entire LVM lookup alan -- Optimists say the glass is half full, Pessimists say the glass is half empty, Developers say wtf is the glass twice as big as it needs to be? Alan McKinnon alan at linuxholdings dot co dot za +27 82, double three seven, one nine three five -- [EMAIL PROTECTED] mailing list
