Does LVM affect performance

[Derek Broughton]

Scott Medling wrote:

> I'm using LVM on top of two RAID 5 arrays and the only thing I notice is
> that the RAID 5 uses about 1% of my 1.8GHz P4 and I don't see LVM, so it
> must use less than that of the CPU.  I can't come up with a logical reason
> why it might affect disk IO or RAM usage noticeably (but it has to store
> it's information in RAM somewhere).

I shouldn't expect LVM to affect either disk IO or RAM - there'll be some
overhead in mounting the partitions, but once mounted I would expect them
to look exactly like any other partition to the OS.   That is, if the
partition contains an Ext2 filesystem, all the in-memory structures telling
the OS where to put or get data are identical to an Ext2 filesystem on a
physical partition.
-- 
derek