To update esx/esxi using a downloaded bundle on a web server, run the following command from a shell command prompt (console/ssh):

esxupdate --bundle http://web.server.name/path/to/files/update-from-esx4.1-4.1_update01.zip update

*Update*

For esxi 5, run the following command (must be an absolute path to file)

esxcli software vib install --maintenance-mode --depot /scratch/downloads/ESXi500-201207001.zip

I was trying to tune an applications performance, but was having issues where it was taking a long time (~5 minutes) to delete 10,000 rows from an innodb table using an indexed field to select the rows to delete. It did not matter whether these rows were deleted in individual queries, or as a single query. I added the following options to /etc/mysql/my.cnf and the query dropped down to 0.3s (a reduction of 1000 times the original time).

innodb_buffer_pool=3G
innodb_log_file_size=256M
innodb_flush_method=O_DIRECT
innodb_log_group_home_dir=/var/lib/mysql2

I was working at a site where outlook would continually prompt for the username and password, even when they were entered correctly. If I went into the mail account settings and unticked the "Only connect to proxy servers that have this principal name in their certificate" checkbox, the user would be able to authenticate, but after exiting outlook and re-opening the option was re-enabled, and the certificate name that it was looking for was filled in, which caused problems authenticating again.