On 11/14/2010 12:41 AM, Richard W.M. Jones wrote: > On Fri, Nov 12, 2010 at 06:26:48PM +0000, "Jóhann B. Guðmundsson" wrote: >> *DE could consider switching the default to use EXT4 directly without >> LVM. [1] >> 1. http://fedoraproject.org/wiki/Features/NoDefaultLVM > > The "Detailed Description" seems contradictory: > > | LVM provides very little benefit for most Fedora users, at the cost of > | performance and complexity: > | > | * Certain filesystem features (ext3 barriers) are unavailable when run > | on top of LVM. > > Isn't this just a bug which should be fixed? (I actually thought this > had been fixed already) > > | * Software RAID performance is greatly reduced when layered on LVM. > > But the stated task is to get rid of LVM except for "experts in > storage administration" (from the next section of the same document). > Who will presumably be the only ones wanting Software RAID. The > non-experts won't know anything about Software RAID, so they won't be > affected by this performance problem with LVM. Can someone point to specific details about this? I did some benchmarking a while ago of raid-1 vs. raid-5, raid-1 plain vs. raid-1 with lvm, etc. and LVM didn't really show up as a performance issue at all. > | * LVM partitions are not automatically assembled by the desktop systems. > > I'm not sure what this one means. "assembled" as in what happens when > you spread a VG over multiple block devices? > > Anyway, I think LVM is jolly useful: I've used plain partitions for a long time because lvm always looked weird to me but then I looked into it and nowadays I don't want to live without it. The ability to have the logical partitioning indepedent of the physical storage is a must-have for me. > - You can expand the root filesystem (eg. into spare space or > across block devices). > > - You can live pvmove filesystems from one device to another. That one actually saved my ass once on a 48 disk 30TB storage system because the controller was acting up. > It may be that the tooling is not there to make these features > available for non-experts, but that's a problem with lack of tools, > not with LVM. Partition tables are horrible and inflexible in > comparison to LVM. > > Can we at the very least have some numbers backing up the supposed > performance problems? Yeah, in my benchmarking I couldn't really confirm this so if there is a problem I'd like to see some specifics too. Regards, Dennis -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
