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<div class="moz-cite-prefix">On 1/16/17 11:48 AM, Bob Harold wrote:<br>
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<div class="gmail_quote">On Mon, Jan 16, 2017 at 12:14 PM,
Drew Derbyshire <span dir="ltr"><<a
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href="mailto:swhobbit@derbyshire.us" target="_blank">swhobbit@derbyshire.us</a>></span>
wrote:<br>
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.8ex;border-left:1px #ccc solid;padding-left:1ex">As an
aside ...<br>
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The thought of putting recovery state/log files (i.e. the
DHCP leases file and its backup) on a RAM disk to make top
look pretty leaves me dismayed. That leaves zero local
protection against a system crash (or misguided deliberate
reboot).<br>
<br>
And yes, the server has been running 346 days -- Doesn't
matter. Services can be five nines reliable, but hardware
won't be.<br>
<br>
An SSD, or if you prefer multiple SSD units configured as
a raid, will give you the same order of performance
without the premortem fodder.<br>
<br>
The machine should be audited for other critical files
which are written to volatile storage, and moved to the
SSD or other storage as well.<br>
<br>
-ahd-
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<div>I agree that putting state in ram is a concern, but
with a failover pair, there should be a duplicate copy on
the other server of all but the very latest changes.
There is a risk when one server is rebooting, so having a
copy of the backup lease file on real disk would help.</div>
<div>I think SSD (particularly write speed) is still orders
of magnitude slower than ram.</div>
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<div>That said, I would not ever want to have both servers
rebooted at the same time, or even restart DHCP at the
same time. Restart one, allow it to sync data and get to
normal-normal, then restart the other.</div>
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I would suggest the performance difference between RAM and SSD is
meaningless to the client. But the whole environment (like how much
traffic the one DHCP server is handling) has a subtle strangeness
about it which makes me nervous. <br>
<br>
But Not my servers. Not my pager going off.<br>
<br>
Good to hear both servers are back online. We'll leave it at that.<br>
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