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<div class="moz-cite-prefix">Op 13-6-2013 7:52, Adam Goryachev
schreef:<br>
</div>
<blockquote cite="mid:51B95E32.6030506@websitemanagers.com.au"
type="cite">
<pre wrap="">On 13/06/13 14:29, Robinson, Eric wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I really appreciate everyone's input but everyone misunderstood the
question I was really asking. It's my fault for mentioning rsync. I
fully understand the difference between how rsync works and how drbd
works. We use them both all the time. But the real question is more high
level. We have been told that even if you stop the mysql service, you
still cannot backup an innodb database by simply copying the files from
one server to another. We have been told that the mysql service will not
start properly on the new server even if you make a 100% exact copy of
all the files from the old server. If that is true, I don't understand
how using drbd can work with innodb tables, since it basically just
makes a copy of the files to another server. Am I asking the question right?
</pre>
</blockquote>
<pre wrap="">
A fraction of common sense should tell you that this is baloney (well,
almost).
Consider, what does mysql need, in order to function properly?
A) The various binary/executable files and scripts
B) Probably some log files/directories (depending on config)
C) Maybe /run or /var/run etc to create some lock file or similar
D) The DB files
Do they claim that shutting down the machine, removing the drive,
installing into a new machine, and turning on the new machine will also
not work?
What is the difference to the above, compared to using DRBD to sync the
entire drive?
what is the difference is you only sync the DB directories but ensure
matching versions/locations of config files and executables?
MySQL doesn't read any magic number of figure and decide it's suddenly
on a different machine and not work (at least, open source, unlicensed
versions, maybe licensed/paid for versions are different). As long as
the files exist, in the expected locations, and are not corrupt, then it
will work.
</pre>
</blockquote>
You're right, but what they mean to tell that InnoDB stores it data
in a very different way and you can't copy stuff around as easy as
with MyISAM. With MyISAM, you just can take the files of a single
database an put them on any other MySQL machine and you're good. It
is not that easy with InnoDB. Having said that, InnoDB has some very
nice live backup tools, so no need to bother with a copy of the
files. However I can understand that this feels very safe... :-)
Bottomline is, it will run fine on top of DRBD, just keep the
configs the same on both machines, but you already wanted to do
that. No problems with failovers and stuff.<br>
<br>
@Eric: Did you have a look at Percona's version of MySQL? They have
what they call 'ExtraDB', which is just their tuned InnoDB version
(backwards compatible). Gives very good performance They also have a
nice set of tools to go with it, also for doing 'hot' backups. We
hired one of their consultants for our MyISAM to InnoDB migration
and go some good tuning and tips from it. Oh, I don't own any
Percona stock, in case you wondered...<br>
<br>
Kind regards,<br>
<br>
Dirk<br>
<blockquote cite="mid:51B95E32.6030506@websitemanagers.com.au"
type="cite">
<pre wrap="">
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