On Mon, Nov 07, 2011 at 08:36:10AM -0200, Lucas Mocellin wrote: > Hi everybody, > > I'm having some issues with PostgreSQL 9.03 running on FreeBSD 8.2 on top > of VMware ESXi 4.1 U1. > > The problem is query are taking too long, and some times one query "blocks" > everybody else to use the DB as well. > > I'm a network administrator, not a DBA, so many things here can be "newbie" > for you guys, so please be patient. :) > > Clonning this database to another machine not virtualized, any "crap" > machine, it runs a way fastar, I've measured one specific "SELECT" and at > the virtualized system (4GB RAM, 4 processors, SATA disk, virtualized), it > took 15minutes!, in the crap machine (2GB RAM, 1 processor, SATA disk, NOT > virtualized), it took only 2!!! > > I always think the bottleneck is disk I/O as I can see from the vSphere > performance view, but the virtual machine is using exclusively the SATA > disk with no concurrency with other machines. > > how do you guys deal with virtualization? any tips/recommendations? does > that make sense the disk I/O? any other sugestion? > > thanks in advance! > > Lucas. Hi Lucas, Virtualization is not a magic bullet. It has many advantages but also has disadvantages. The resources of the virtual machine are always a subset of the host machine resources. In addition, the second layer of disk I/O indirection through the virtual disk can effectively turn a sequential I/O pattern into a random I/O pattern with the accompanying 10:1 decrease in I/O throughput. I would recommend testing your I/O on your virtual machine. Regards, Ken -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
