Watching performance on a DHCP Server
David W. Hankins
David_Hankins at isc.org
Fri Feb 8 22:53:15 UTC 2008
On Fri, Feb 08, 2008 at 03:27:23PM -0600, Blake Hudson wrote:
> Seems like it would make sense that this I/O could be non-blocking....
That's just it, we feel it can't be, or else you run the risk of
duplicate allocations on a restart. The simple way of saying it is
the database isn't consistent.
It's the same sort of thing that makes an e-commerce system want to
'SQL COMMIT' before replying down an http socket that an order has
gone through. If you crash and need to recover data from disk, you'd
rather have the customer's money and order than an order number that's
a duplicate for some other customer because your system walked over it
when it came back up.
Same deal; we deal in leases which are a lot like transactions. A
promise is made that an address is good for a given time. Money may
not change hands, but things break if you reneg, things work if you
delay or even drop the request waiting...the far end retransmits.
I don't mind it being configurable behaviour, heck all you have to do
is comment out a single line and rebuild the sources if you were
intent on it, but we haven't got a patch for that.
Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
Why settle for the lesser evil? https://secure.isc.org/store/t-shirt/
David W. Hankins "If you don't do it right the first time,
Software Engineer you'll just have to do it again."
Internet Systems Consortium, Inc. -- Jack T. Hankins
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