application availability monitoring

The availability of any enterprise application is only as good as the monitoring solutions utilized. The reason being that a well thought out / well deployed monitoring solution not only detects when an application has failed to respond to requests, it can also take steps to being remedy the problem without involving human intervention. The last thing any admin wants to be waken up at 3a only to hit the restart button for the downed service. (more…)

packet capture repository

Ever asked yourself the question of “I wonder what a trace of my favorite application protocol looks like”? I did that today and found myself browsing through the collection of sample packet captures on wireshark.org. The collection is quite impressive. There are nearly 50 categories of packet captures available, from HTTP to NTP to SQL to IPSec to Kerberos. You can even check out a capture of a slammer worm! Anyway, I thought this is a great resource and want to pass it on.

‘vi’ quick command references

I’m a die hard vi user and still prefer using vi to edit plaintext files. There were some discussion on twitter on vi awhile back and I thought I’d share my own command cheat sheet for vi in edit mode. This is not quite a full tutorial but makes for a useful reference.

Editing Text…

i Insert before cursor
I Insert before line
a Append after cursor
A Append after line
o Open a new line after current line
O Open a new line before current line
r Replace one character
R Replace many characters
x Delete character to the right of cursor
X Delete character to the left of cursor
D Delete to the end of the line
dd Delete current line
:d Delete current line
yy Yank the current line
p Put after the position or after the line
J Join lines
u Undo last change

Moving the cursor around… (more…)

clustering versus load-balancing

Seems that often times the concept of clustering is often mixed up with that of load-balancing. I thought I’d quickly write something up to help clarify the difference between the two.

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