[DRBD-user] drbd+mysql+innodb

[Louis]

Hi Paul,

I'm curious to find out from you which you use DRBD at different sites, do you mean your drbd notes are in different datacenter/location? Does it slow down the whole operation?

Regards
Louis





>________________________________
> From: Paul Walsh <Paul.Walsh at bcu.ac.uk>
>To: drbd-user at lists.linbit.com 
>Sent: Thursday, June 13, 2013 8:20 AM
>Subject: Re: [DRBD-user] drbd+mysql+innodb
> 
>
>
>
>
>On 13/06/13 05:29, Robinson, Eric wrote:
>
>ProActive Software 
>>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?
>> 
>>--
>>Eric Robinson
>>
>> 
>>
>For what it's worth, we run MySQL+InnoDB on DRBD and use
    Heartbeat+Pacemaker for failover between nodes at different sites. 
    This supports our Moodle VLE which is an important part of our
    course provision.  As yet we have had no problems. We also use mysqldump to back up databases.
>
>To quote from Wikipedia:
>
>" InnoDB recovers from a crash or other unexpected shutdown by replaying its logs"
>
>These logs, by nature of the fact they're on a DRBD device, will
      be identical on both nodes, so if, say, node-A fails, node-B can
      assume Primary role for the DRBD device and mysql can start up,
      replaying its logs to may sure the data is up-to-date. 
>
>I think whoever told you mysql would not start properly was
      possibly referring to what would happen if you simply copied all
      the files (with, for instance, rsync) whilst the database was
      active.
> 
>-- 
Paul Walsh  Head of Unix/Linux Systems Services,
Corporate ICT,
Birmingham City University,
City North Campus, Perry Barr,
BIRMINGHAM B42 2SU, UK 
Tel:    +44 (0)121 331 5708
Fax:    +44 (0)121 356 2875
Mobile: +44 (0)7974 150 421 
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