Filesystem performance exhasperatingly horribly unusably slow.
Ok, I'm brand new at playing around with Oracle's VM, so maybe I'm doing something wrong, but I'm getting completely unusable filesystem write performance from my first VM test system.
The VM server is a Dell PE 2600 with dual 3.2GHz xeon processors, 4GB memory, two PERC 4 raid controllers with a 300GB internal array for the main Linux system volume, and an external 1TB array on the 2nd PERC card for the /OVS volume. The raw hardware, though 5 years old vintage, is no slouch, and ran Windows and regular Linux screamingly fast for its past production deployments. The VM server installation, is a fresh install of the 32-bits version VM server 2.1.2, using all the defaults , from the bootable ISO image.
I have the VM Manager running on a separate machine, a high-powered HP desktop.
I created my first virtual machine from the OVM_EL5U2_X86_ORACLE11G_PVM template and in the web manager, I added two more (non-shared) virtual disks, to hold my application software and database to the virtual machine. The first virtual disk is 12GB in size, and the 2nd one is 100GB. The 12GB virtual disk created and attached pretty quickly, the 100GB virtual disk took many hours, I left it run overnight to finish. In the virtual machine's console, I ran fdisk to put one partition on each of these two virtual disks, and ran mkfs to put one ext3 filesystem on each new partion, edited the /etc/fstab to add the two new filesystems, and manually mounted them. Making the filesystem on the 12GB disk/partition went fast, only a few seconds to complete. Doing the same on the 100GB partion took much, much longer.... over an hour :-(
The dismay really started when I began copying a 4.25GB Oracle export .dmp file of my database from the /u01 filesystem (which came by default with the vm created from template) over to my newly created 100GB virtual disk filesystem. The simple file copy took over 45 minutes! That works out to be only about 1.5MB/second. Is something wrong here, or is this the kind of write performance to be expected? I've read all kinds of whitepapers that claim that performance of a virtual machine should typically be in the realm of 80-90% of native Linux running directly on the raw hardware, but what I'm seeing here is filesystem performance equivalent to an IDE disk in an old 1990's desktop machine. If that's all there is, then I should just cut this experiment short and consider virtualization to be only an academic curiosity or suitable only for trivially small production use.