On Fri, 2016-01-22 at 14:56 -0600, NightLightHosts Admin wrote: > On Fri, Jan 22, 2016 at 11:02 AM, Ed Heron <Ed@xxxxxxxxxxxxx> 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? Yes, in a test environment, I am mirroring a Logical Volume with a RAM disk to increase the perceived speed of the disk. I'm expecting to convert a live guest to this type of setup, this weekend. I was asking 2 questions. 1. Should I expect a significant increase in speed in a real world environment? With enough RAM, a good caching system will eventually do a similar function. This is almost like pre-loading a cache. 2. Should I document the process for others? I'm using CentOS 5 now, which is on it's way out, but I would update the documentation to include CentOS 7 when I upgrade my servers. _______________________________________________ CentOS-virt mailing list CentOS-virt@xxxxxxxxxx https://lists.centos.org/mailman/listinfo/centos-virt
