Don't do this at home

R

Roedy Green

One of my favourite sites was down for a couple of days. I wrote to
find out what had gone wrong.

"Our nitwit hosting service decided to move all of the sites to
different servers (on a weekday!). Their planned 1-hour move (which
they failed to inform us about) turned into a 36-hour downtime, and
we're still cleaning up the debris."

In case you attempt such a shuffle:

1. get the new system up before you erase the old. Something might be
missing from the backups.

2. move one site at a time.

3. do it in the middle of the night on a weekend to give yourself time
to recover from a foul up without seriously impacting the customers.


--
Roedy Green Canadian Mind Products
http://mindprod.com

"There is an evil which ought to be guarded against, in the indefinite accumulation of property,
from the capacity of holding it in perpetuity by... corporations.
The power of all corporations aught to be limited in this respect.
The growing wealth acquired by them never fails to be a source of abuses."
~ James Madison (born: 1751-03-16 died: 1836-06-28 at age: 85)
 
A

Arne Vajhøj

Roedy said:
One of my favourite sites was down for a couple of days. I wrote to
find out what had gone wrong.

"Our nitwit hosting service decided to move all of the sites to
different servers (on a weekday!). Their planned 1-hour move (which
they failed to inform us about) turned into a 36-hour downtime, and
we're still cleaning up the debris."

In case you attempt such a shuffle:

1. get the new system up before you erase the old. Something might be
missing from the backups.

2. move one site at a time.

3. do it in the middle of the night on a weekend to give yourself time
to recover from a foul up without seriously impacting the customers.

And the difference for sites running Java to sites running anything
else is ????

Arne
 
R

Roedy Green

It will always be the middle of the night in some time zone or other.

That's true, but if you look at the hit distribution, there will be an
optimum time of day when hits are lowest.
--
Roedy Green Canadian Mind Products
http://mindprod.com

"Any one who considers arithmetical methods of producing random digits is, of course, in a state of sin. For, as has been pointed out several times, there is no such thing as a random number — there are only methods to produce random numbers, and a strict arithmetic procedure of course is not such a method."
~ John von Neumann (born: 1903-12-28 died: 1957-02-08 at age: 53)
 
J

John B. Matthews

Roedy Green said:
That's true, but if you look at the hit distribution, there will be
an optimum time of day when hits are lowest.

How are those customer different, other than being fewer in number?
 
R

Roedy Green

How are those customer different, other than being fewer in number?

I don't understand. For any given website, there will be an optimum
time to take it down depending on where its customers are located.
--
Roedy Green Canadian Mind Products
http://mindprod.com

"Simplicity is prerequisite for reliability,"
~ Edsger Wybe Dijkstra (born: 1930-05-11 died: 2002-08-06 at age: 72)
 
J

John B. Matthews

Roedy Green said:
I don't understand. For any given website, there will be an optimum
time to take it down depending on where its customers are located.

I had imagined you intended to use an optimization function that
minimized, for example, the number of people inconvenienced by scheduled
downtime. As rossum noted, this may be strongly correlated with
location. If you view all customers as equally valuable, the minimum
will be optimal for you, but less than optimal for those customers in
certain locations who are systematically (dis)affected. Perhaps they are
remote relative to the bulk of your customers or have low bandwidth
connections or receive variable power. The problem would be compounded
if the service represents an effective monopoly.

The point is this: The utilitarian application of an optimization
function might work well to minimize packaging waste or network latency;
it may have unexpected consequences when applied to people.
 
R

Roedy Green

Agreed, but that optimum time is not always "in the middle of the
night on a weekend" at the location of the server or any specific
user.

Virtual middle of the night on the virtual weekend then.
--
Roedy Green Canadian Mind Products
http://mindprod.com

"Simplicity is prerequisite for reliability,"
~ Edsger Wybe Dijkstra (born: 1930-05-11 died: 2002-08-06 at age: 72)
 

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