Hello.
After spending lots of hours in testing and analyzing I/O problems, I decided to put our problem towards VMware support. Unfortunately our support contract is not valid at the moment, so I post our problem here 
.
This is our scenario:
- Linux Distribution: 2.6.32-5-amd64 (Debian 2.6.32-45)
- 1 x physical blade server (HP ProLiant BL460c G1) with 64GB RAM and a Quad-Core Intel Xeon, 1866 MHz CPU and RAID 1 with 10K SAS 146GB HDD
- 1 x virtual server based on ESX 5.1 with VMTools installed, 10GB vRAM, 4 vCPUs
- Partition formatted with EXT3 on both servers
- Both servers have a mysql database with 3GB size running (Magento shop system)
In this scenario we do the "optimize table" function for all tables.
These are the results:
Physical system: average duration = 5 minutes
Virtual system: average duration = 12 minutes
With IOZone we also did some comparisions (with the -a flag) and result was, that virtual environment is not quiet slower as physical.
Any ideas? Is it possible, that (v)RAM makes the difference? But RAM usage is quiete normal on VM when starting the optimization command...
Bye Thomas