A kernel developer, I think from Red Hat, said on a list that lvm is 2% slower than a physical partition. Considering the obsession some folks have with performance, that seems like an awful lot to give up for some flexibility which really may not be at all helpful to some users. The reason for the overhead is basically that when you send the command over the wire to the actual disk, you have to give it an absolute Logical Block Address - relative to the beginning of the whole hard drive. Hard disk drives don't know from partitions or logical volumes. To convert a partition offset into a disk offset, you just add the starting sector of the disk. To get that starting sector, you have to look it up in a data structure that's maintained by the disk driver. I don't know how LVM is implemented, but I imagine there are some extra layers of indirection that enable that flexibility. The data structures involved will be more complex, as will be the code. They will also be more likely to be buggy as well. I've been setting up a bunch of partitions to run virtual machines on, for cross-platform development. While it's a PITA to keep repartitioning my RAID 5, I figure the extra effort is worth it for that consistently 2% faster disk I/O. Don Quixote quixote@xxxxxxxxxxxxxxxx http://www.dulcineatech.com/ Dulcinea Technologies: Software of Elegance and Beauty -- fedora-list mailing list fedora-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
