[linux-lvm] lvm lowers transfer rate

[Innocent Azinyue Ndangoh]

Hi there,

I have 4 fiber channel disks, on which I intend to build a logical volume 
using lvm. Before creating the logical volume, I run an I/O test on the 
disks, which revealed that the disks each would do 10MBytes/sec I/Os.

However, when I create a logical volume, spanning all 4 disks using RAID0, I 
realize that the transfer rate now drops. Instead (10 * 4)MB/s, I get 
something close to 30MB/s. Am I doing something wrong?!?

My procedure to create logical volume:
1. Do fdisk on drive
- do -o (DOS option).
PS : setting the type to linux lvm(8e) results in errors on creating the 
logical volu7me
- do pvcreate on the disk(s)
- do vgcreate on all physical volumes requested
- do lvcreate on created volume
- mkfs.ext2 on logical volume
- mount  log. volume

thanks for your time

Innocent


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