[CentOS-virt] LVM mirror database to ramdisk

Sun Jan 24 00:27:53 UTC 2016
Ed Heron <Ed at Heron-ent.com>

On Sat, 2016-01-23 at 09:27 -0600, Robert Nichols wrote:
> On 01/22/2016 11:02 AM, Ed Heron 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.
> If that were running under Linux rather than Windows I'd suggest just
> giving that extra 35GB to its kernel and letting its normal caching
> keep everything in RAM. Whether Windows (7 or Server) would be clever
> enough to do that is another question. Of course you could just let
> the Linux host do the caching, but that runs the risk of other VMs
> or host activity displacing some of that cache and affecting the
> performance of your database VM.
  Yes... You've got much of my thought process.

  The RAM disk mirror pre-loads the database into memory and forces it
to stay in RAM.