Huge Pages is a feature available in later Linux kernels that provides two important benefits: 1. Locks the memory available to huge pages, so it cannot be paged to disk 2. Make the TLB (translation lookaside buffer) much smaller on…
Author: Steve
CLUSTERING_FACTOR
I had to analyze a performance problem this morning, and it occurred to me it is a good example of troubleshooting queries impacted by the clustering_factor of an index. As such, below is the email exchange. I took a look,…
Where is my close button?!!
So I just updated to Ubuntu 10.4, and the first thing I noticed is the fact the close/minimize/maximize buttons were switched to the top left hand corner from the right corner. I have no clue why something as standard as…
Converting lock modes to determine what the root cause is
Take name|mode print hex(1415053316) …and convert to hex… 0x54580004 …then take the first two, second two, and last four values to get the reason code. 54 in hex = T 58 in hex = X and 0004 = 4. This…
logrotate configured by mere mortals
This will provide a way to implement log file rotations by a non-privileged users using the standard Linux logrotate infrastructure. For our test case, we set up a log file that looks similar to a “normal” log file we may…
memset example
This is just a quick note so I don’t forget. If you don’t run a memset, the memory will only be allocated, but not shown as being used in the OS. int main() { int i = 1; while(i++ <…
VIP migrations
We start with a two node cluster with all components up. linux2:oracle:tst10g2:/home/oracle>./crsstat.ksh HA Resource Target State ———– —— —– ora.linux1.ASM1.asm ONLINE ONLINE on linux1 ora.linux1.LISTENER_LINUX1.lsnr ONLINE ONLINE on linux1 ora.linux1.gsd ONLINE ONLINE on linux1 ora.linux1.ons ONLINE ONLINE on linux1 ora.linux1.vip…
Troubleshooting “library cache lock”
If you have several users waiting on a library cache lock, they are normally blocked by one user that is waiting on a library cache pin. You have to find out who is blocking the user waiting on the library…
cx_Oracle cursor fetching behaviour
I have noticed this over the past few months, and think I still may be missing something. Given the following code… #!/home/oracle/local/bin/python import cx_Oracle import sys con = cx_Oracle.connect(“howards”,”******”,”perfrac”) con.cursor().execute(“alter session set events ‘10046 trace name context forever, level 12′”);…
Delete files older than another file
Using the find command in *nix is very useful. You can specify that you would like to find files newer than another file, or older or newer than a certain time. You cannot (directly) find files older than another file.…