[CentOS] tinydns/djbdns opinion poll

[Bill Campbell]

On Thu, Feb 12, 2009, Les Mikesell wrote:
>Bill Campbell wrote:
>>
>>>> That sounds like the kiss of death for any critical service.  Can't it 
>>>> figure out ahead of time that this is going to happen and let the 
>>>> service keep running unchanged with a warning message about needing the 
>>>> update instead?
>>> You're missing the point.  If the service is already running, the
>>> changes won't take effect until you restart the service with the new
>>> binaries. And the whole patching exercise is what maintenance windows
>>> are for, anyway.  Note that it's critical SERVICE, not critical SERVER.
>>> The former is more important than the latter, so ideally you should be
>>> able to take down the latter in order to upgrade one implementation of
>>> the former.
>> 
>> I understand the distinction very well.  In the time we have been using
>> this method, we have never taken down a service for any significant period
>> of time (the services are restarted on installation by the RPM SPEC files'
>> %pre, %post processing).
>> 
>> Of course we don't do things that are likely to take a critical service
>> down without proper prior planning (often found out the hard way on our own
>> systems :-).  If an update is likely to have an impact on operations, it is
>> scheduled during a maintenance window.
>
>In other words you'd dedicated sufficient human resources to undo 
>whatever damage the package management system causes...

Isn't that what our customers are paying us to do?

That has to be true now matter how one is doing updates.

I have personally updated clamav on more than 50 machines in an afternoon
without having any of them down for more than a minute, and that time
mostly because clamav takes a while to restart.

FWIW, we normally have clamav updates installed at all our client sites
with 24 hours of the first notice that there's a new version out from
swatch looking at the freshclamav.log file.  This includes downloading the
new tarball, updating the OpenPKG SRPM, building, testing in-house, and
deployment.  Often this is complete before people on this CentOS list start
asking questions about the update or saying it won't build.

Oh, and these updates are on a variety of Linux systems ranging from SuSE
9.0 Pro, SLES9, SLES10, CentOS 4.5 through CentOS 5.x, and at least one
FreeBSD box -- all from the same SRPM file.

Bill
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