Thursday, February 26, 2009

Watching dd progress

Fabian (of RPMforge and CentOS fame) wrote a blogpost about using pv (pipe viewer) to watch a datastream through a pipe, such as a dd-over-ssh copy from one machine to another. I knew pv existed, but I've often used dd on systems where pv wasn't available (e.g. rescue CD), or used dd without sending data through pipes. Even in these situations, you can keep an eye on dd's progress: open another terminal window, then run

# while sleep 10; do killall -USR1 dd; done


and switch back to the shell where dd is running. It will show its status every 10 seconds.
Note, your version of dd needs to support this. The dd from RHEL3 doesn't (version 4), but the dd from RHEL5 does (version 5) !

Wednesday, February 25, 2009

scoop: VMware vCenter on CentOS 5

Today at VMworld Europe 2009, VMware demoed a preview of their vCenter management server running on Linux in a virtual machine, pre-packaged in virtual appliance format. Aside from that fact that this is a great idea with all the advantages that virtual appliances have to offer, and that a lot of people have been waiting for, it was a really pleasant surprise to me that they chose to build it on top of CentOS 5 !
It'll take months before a final version will become available for download to VMware vCenter customers, but it's going to happen, that's for sure.
Kudos to the CentOS team !

Saturday, February 7, 2009

vCenter forgot my ESX is in standby mode. What now ?

I used VirtualCenter (vCenter) to put an ESX in standby mode. I restarted VirtualCenter for Windows patches, and now VirtualCenter says the ESX host is "not responding", and doesn't give me the option to wake it from standby mode. Fortunately, the solution is right there under your fingertips: do manually what VirtualCenter would have done for you:
Log on to another ESX on the same network, get the MAC address(es) of the sleeping ESX host, and run:
# ether-wake -i vswif0 aa:bb:cc:dd:ee:ff
You could optionally repeat this for every interface you know of the sleeping ESX. Remember to use the real MAC addresses of the real NICs, not the virtual MAC addresses of service console ports, vmkernel ports, or virtual machines.
After a couple of minutes, VirtualCenter will notice that the host is responding, and will connect it again. If you wish, you can put it in standby mode again using the VI-Client.

If you don't know the MAC address of the host in standby mode, you would need to look for it in the VC database, but you can also find it in /etc/vmware/esx.conf, if you happen to have a backup (such as a vm-support dump). Look for /net/pnic/child[*]/mac values.