Presented in the now-traditional illustrated form:

; sdig ns gcluk.netns1.gcluk.net.ns2.gcluk.net.; dig mx web1.gcluk.net @ns1.gcluk.net[...];; ANSWER SECTION:web1.gcluk.net. IN A 65.98.36.90;; AUTHORITY SECTION:web1.gcluk.net. IN NS .

(TTLs have been omitted for clarity.)

That

The problem with LiveJournal is that youcan't stop partway through reading your friendslist; unless you have abetter memory than me, once you start reading it you need to read allthe way back to where you last stopped. The result is somewhat likeSpace Invaders; a stream of entries comes at you and you have to readthem all or die. In turn, this makes reading LiveJournal friendslistsnot a casual activity; if I can't commit enough time to read all of thenew entries that have

This is the kind of hack where I present the Python code first andexplain it later:

def memo1(func):  def _wrap(self):    r = func(self)    setattr(self, func.func_name, \            lambda : r)    return r  return _wrapclass Foo(object):  ...  def invar(self):    return complex(self.field1) or \           complex2(self.field2)  invar = memo1(invar)

Here,

Since our mirrors of the Valles Marinerismovie clips have been running fortwo days now, it's time to look at how things turned out. I'll startwith the raw numbers:

• On Monday, we transfered 198.64 gigabytes in 7,781 requests, despitenot getting much traffic until about 10am Eastern time.
• On Tuesday, we transfered 316.36 gigabytes in 13,979 requests.

(At a later date I may wrangle

I was recently reminded that Linux's iostat command is what I call'overly helpful'. It's not that it lies to you, exactly; it's that iostat is a little bit too eager to please people reading its output,particularly iostat -x output. There are a number of issues.

(The rest of this assumes that you're familiar with the iostat -x fields.)

The fatally flawed field is svctm , the 'average service time' forIOs. It would be

I spent a chunk of this weekend preparing a mirror for a high loadenvironment. The mirror only needs to serve a couple of largevideo clips , but they're going to be linked from a high traffic website , so we expect a lot of (simultaneous)connections and a lot of outgoing bandwidth.

I made a generic mirror url, using a new hostname that I had to put intoa new sub-zone in our DNS . Right now it has two A records, each with a five minute TTL

Hotmail had an amazingly good week this time around:

• 5 messages accepted.
• 2 messages rejected because they came from non-Hotmail emailaddresses.
• no messages sent to our spamtraps.
• 6 messages refused because their sender addresses had already hitour spamtraps.
• only 1 message refused due to the origin IP address being in the CBL(and now in the SBL, as SBL34115 ).

Muting the happiness is the fact that the one CBL-rejected messagewas from a sympatico.ca address, and several

One thing I did today was set up DNS for a hostname that we may needto re-point elsewhere very rapidly. This caused me to realize somethingimportant:

Setting low TTLs doesn't mean squat if you can't cause secondaries toreload on command.

Low TTLs mean that people will re-query A records frequently, but thatdoesn't help me change where the traffic is going if my secondarieshaven't updated to my new set of A records. Unfortunately, none of thesecondaries for

Every so often, I run into web design trends that I simply don'tunderstand. Since I've already grumbled about small font sizes , today's contestant is the mysterious case of thevanishing links.

Technically they haven't vanished. Instead they've carefully beengiven a colour that is almost exactly the same as the regular textcolour. Sometimes even exactly the same as the regular text colour.Ironically, in this situation the 'click here' style of link textactually becomes good, because