This command test memory to memory copies over rsh (a low overhead protocol). This should be about all the throughput you are going to get from your network adapters:

export RSH_TEST_HOST=hostname
time dd if=/dev/zero count=1000 bs=1M | rsh $RSH_TEST_HOST dd of=/dev/null

If you want to test TCP, here’s the same thing using FTP:

ftp> put "|dd if=/dev/zero bs=1M count=1000" /dev/null

and NCFTP with time:

time dd if=/dev/zero bs=1M count=1000 | /usr/local/bin/ncftpput -u USER -p PASSWORD -c HOST /dev/null

If a process has to wait for memory pages, system performance is impacted. The system keeps a pool of available pages just for this. To see if we need to adjust minfree and maxfree, first find out what they are set to now:

Sometimes you want to find a Process ID associated with network activity on your system. For example, you may be looking at the sockets in an ESTABLISHED state on your system and you see one that cannot be readily identified to a running process.

If an installation or migration fails, you can run the install in “debug” mode. Boot from the CD as normal, select the console and language. Then type “911”. The screen should silently refresh without saying anything about an invalid selection. Now continue the install as normal. The output of the scripts the install process runs with show up on the screen. It’s sometimes a lot of data, but you can often see what’s wrong with the install this way.

If you want to expand a LUN on AIX, you have to update the VG to see the change.

Did you know you can burn a bootable mksysb image from your CDRW/DVDRW capable PC or laptop when the server/LPAR doesn’t have one available? Here’s how:

To setup SOL to access the internal serial port of the IBM JS SeriesP blade as a console:

Here is a script that removes the oldest entries in the /var/adm/wtmp file, but keeps a reasonable history:

Sometimes your P4 (and maybe P5?) DLPAR goes to lunch and the dynamic menu options don’t appear.  To reset everything on the HMC, IBM recommends we run this from the offending LPAR:

/usr/sbin/rsct/install/bin/recfgct

If that doesn’t work, try:

/usr/sbin/rsct/bin/rmcctrl -z
/usr/sbin/rsct/bin/rmcctrl -A
/usr/sbin/rsct/bin/rmcctrl -p