I'm still running CentOS 5 with Xen.
We recently replaced a virtual host system board with an Intel S1400FP4, so the host went from a 4 core Xeon with 32G RAM to a 6 core Xeon with 48G RAM, max 96G. The drives are SSD.
I was recently asked to move an InterBase server from Windows 7 to Windows Server. The database is 30G.
I'm speculating that if I put the database on a 35G virtual disk and mirror it to a 35G RAM disk, the speed of database access might improve.
I use local LVM for my virtual disks with DRBD on top to mirror the disk to a backup server.
If I change grub.conf to increase RAM disk size and increase host RAM, I could create a 35G RAM disk.
I'd modify rc.local to add pvcreate /dev/ramdisk vgextend vg /dev/ramdisk lvconvert -m 1 --corelog vg/lv_database /dev/ramdisk
Even with lv_database being 35G, it doesn't take long to activate the mirror.
I haven't decided where to put the commands to turn off the lvm mirror. lvconvert -m 0 vg/lv_database vgreduce vg /dev/ramdisk pvremove /dev/ramdisk
I haven't put this in real world use, yet.
On it's face, this might speed up database access. Would we expect it to speed up database access in real world use?
Should I document the process so others could know how to do this? I realize new documentation for CentOS 5 virtualization would be considered obsolete before I wrote it but I'm expecting to test CentOS 7 virtualization in the next few months and, when I am comfortable, I'd upgrade my 18 virtual hosts. I would update the documentation, at that time, as well.