Oracle needs to fix their certification requirements
I have been spending a good bit of my spare time studying for the Oracle RAC certification, and am hoping to get certified by the end of summer. Once thing that annoys me is the fact that you have to attend a vendor training class in order to get certified. This is kinda silly, and I have yet to find a test that I couldn't pass by studying the product on my own (I have 14 certifications, all of which I got by studying vendor documentation). While I can understand that Oracle wants to make money off the certification process, they should be a bit more flexible and allow people to acquire certifications through self-study (I think you learn more when you study material on your own)…
$ read more →Best I/O scheduler to use with virtualized Linux hosts
While reading through the Redhat Oracle 10G best practices document, I came across this gem: "In virtualized environments, it is often detrimental to schedule I/O at both the host and guest layers. If multiple guests access storage on a file system or block devices managed by the host operating system, the host may be able to schedule I/O more efficiently because it alone is aware of requests from all guests and knows the physical layout of storage, which may not map linearly to the guests' virtual storage. Red Hat Enterprise Linux 4 and Red Hat Enterprise Linux 5 guests can use the noop I/O scheduler to allow the host to optimize I/O requests." This makes complete sense, and I am going to have to test out the noop I/O scheduler in my lab this weekend. I'm curious how many folks run the default I/O scheduler in their Xen or KVM guests, and are actually hindering I/O performance by doing so.
$ read more →Generating statistics from the Sun directory server access logs
I have been managing Sun's directory server for close to four years, and it is one of the few products I use that has all the bells and whistles out of the box. One extremely useful feature is the ability to generate statistics from the server access logs. This capability is built into the logconv.pl perl script, which is part of the Sun directory server resource kit (as a side note, logconv.pl is what motivated me to write ldap-stats.pl to analyze OpenLDAP log files). To use the logconv.pl statistics program to analyze your server access logs, you will first need to grab the resource kit from the Sun download page…
$ read more →LDAP indexes
LDAP indexes are extremely useful for speeding up directory searches, and come in four flavors (there are actually more than four index types, but the following four are the most common): 1 Approximate indexes Approximate indexes are useful for speeding up seaches that look for attribute values that sound like a specific value. A good example of this is searching the directory for all first names that sound like "Amy": 2. Equality indexes Equality indexes are useful for speed up searches that perform a direct comparison. The following search would benefit from an equality index: 3…
$ read more →Generating passwords for LDAP
When I generate LDIF entries for new LDAP users, I need to populate the userPassword field with a crypt password or an SHA1 or MD5 hash. Sun's directory server comes with the getpwenc utility to assist with this: In addition to generating crypt passwords, it can also create MD5 and SHA1 hashes.
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