On Fri, Jan 22, 2016 at 11:02 AM, Ed Heron <Ed at heron-ent.com> wrote: > 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. > > I may not understand enough to understand what you are doing, you want to actively mirror this with LVM or?