Scott Ferguson wrote:
On 03/03/14 23:28, Fred Wilson wrote:
On Mon, 03 Mar 2014 12:52:40 +1100
Scott Ferguson <scott.ferguson.debian.u...@gmail.com> wrote:
Which is fine for you, and I can understand and appreciate that, for my
own personal computers my sentiments are similar. However my business
purposes involve meeting SLAs so reboots once or twice a year can cost a
lot of money - so in those circumstances a few minutes makes a lot of
difference. Perhaps that's not something you care about - or it's just
convenient to ignore until your bank/phone/stockbroker/shopping is
interrupted as a result.
http://en.wikipedia.org/wiki/Service-level_agreement
http://en.wikipedia.org/wiki/High_availability#Percentage_calculation
When you pay for a five nines SLA, perhaps for your business web site
hosting, or what your bank/business pays for their trading platform that
means we must be offline a *total* of less than 5 and a half minutes *a
year*. That's begin reboot to all services restarted. Failure to do so
results in penalties that can *very* quickly exceed the annual support
contract. While a great deal of effort and planning goes into shifting
loads so that reboots don't affect production - things don't always work
to plan, so good plans allow for that. Meaning systems must be designed
to reboot in less than the allowed downtime - with a safety margin. If
we can shave a few seconds off reboot time we can shave a large amount
off the support contract price, with the possibility that those savings
are passed on to the consumer.
Anybody who is counting on a fast reboot to maintain a 5 nines SLA is
simply nuts.
that's what redundancy and high-availability configurations are for.
Personally, I'm a lot more worried about what's going to break when we
move to Jessie and
systemd - and all those things I might have to reconfigure. That
involves serious time,
effort, and dollars. And that's before the things that will break
intermittently. I still shudder
every time I think of the impact udev had on our operations, before we
got the subtleties
figure out. (Note: at the moment "we" = "me" and sleepless nights that
impact other work.)
Miles Fidelman
--
In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra
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