Wednesday, June 20, 2012

Wednesday, June 13, 2012

Poor performance when running virtual machines on a local or direct attached SAS storage with IBM HS23 blades

When running virtual machines on a local or direct attached SAS storage with IBM HS23 blades, you experience these symptoms:
  • Slow virtual machine I/O performance
  • I/O starts as expected, but then decreases
  • No errors or events are logged in the vmkernel.log file
  • The esxtop command reports high DAVG values during the slow performance
This issue happens when two VIB files are installed, one by the standard ISO provided by VMware and another by the IBM Customized ESXi 5.0 GA Build.
To workaround this issue run these commands in either the DCUI or via an SSH session:
esxcli software vib remove -n ilfu
esxcli software vib remove -n LSIProvider

Restart the ESXi 5.0 host.
This issue does not occur with VMware vSphere Hypervisor 5.0 Update 1 IBM Customized image.
For more information read the following article from IBM

Tuesday, June 12, 2012

Thursday, June 7, 2012

How to enable ipv6 temporary addresses and make them preferred for outgoing connections in CentOS

Enter these two command from a root shell:
sysctl net.ipv6.conf.all.use_tempaddr=2
sysctl net.ipv6.conf.default.use_tempaddr=2

To make them permanent add these two lines in /etc/sysctl.conf
net.ipv6.conf.all.use_tempaddr=2
net.ipv6.conf.default.use_tempaddr=2
After that restart network service:
service network restart