| From: | Robert Schnabel <schnabelr(at)missouri(dot)edu> |
|---|---|
| To: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, cb <cb(at)mythtech(dot)net>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Is Diskeeper Automatic Mode safe? |
| Date: | 2009-11-16 21:04:37 |
| Message-ID: | 4B01BE65.3060200@missouri.edu |
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Scott Marlowe wrote:
<blockquote
cite="mid:dcc563d10911161250o766faabfyd51dcb6b88ed996(at)mail(dot)gmail(dot)com"
type="cite">
<pre wrap="">On Mon, Nov 16, 2009 at 1:32 PM, Robert Schnabel <a class="moz-txt-link-rfc2396E" href="mailto:schnabelr(at)missouri(dot)edu"><schnabelr(at)missouri(dot)edu></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Ok, so you have sufficiently sparked my curiosity as to whether Diskeeper
will in any way cause Postgres to fail the power chord test. Unfortunately
I have some deadlines to meet so won't be able to test this out until later
</pre>
</blockquote>
<pre wrap=""><!---->
Best time is during acceptance testing before deployment. Failing
that testing it in production on the backup server so you can burn it
to the ground and rebuild it on a saturday.
Note that surviving the power plug being pulled doesn't PROVE your
system will always do that. You can try to simulate the real mix of
load and even replay queries when pulling the plug, only to find the
one corner case you didnt' test in production when power is lost. The
power cord plug can prove a system bad, but you're still somewhat
"hoping" it's really good, with a high probability of being right.
Which is why backup is so important.
</pre>
</blockquote>
Granted, but the point of me testing this is to say whether or not the
Diskeeper service could introduce a problem. If the system recovers
without Diskeeper running but does not recover while Diskeeper is
actively running then we have a problem. If they both recover then
I've answered the question "Have you unplugged the power cord a few
times in the middle of heavy write activity?" I understand that we
can't prove that it works but I should be able to at least answer the
question asked.<br>
<br>
I wouldn't consider my database a production one. I basically use it
to store a large amount of genetic data for my lab. The only time the
database gets use is when I use it. Short of frying a piece of
hardware by pulling the plug I'm not worried about losing any data and
rebuilding is actually quite a simple process that only takes about 2
hours... been there done that when I pulled the wrong SAS connector.<br>
<br>
Bob<br>
<br>
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