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From Alex Huang <Alex.Hu...@citrix.com>
Subject RE: CS 4 Database integrity - mysql server performances
Date Thu, 14 Feb 2013 21:44:27 GMT
Specifically for the question of when max DB connections reach, CS will start to fail individual
operations until DB connections are available again.  There are essential operations such
as the cluster db ping that reserves their own db connections which is not supposed to fail.

--Alex

> -----Original Message-----
> From: Chiradeep Vittal
> Sent: Thursday, February 14, 2013 11:44 AM
> To: cloudstack-users@incubator.apache.org
> Cc: Alex Huang
> Subject: Re: CS 4 Database integrity - mysql server performances
> 
> +Alex since he is opinionated on this stuff.
> 
> In general CloudStack uses transactions and the framework ensures that
> cleanup happens if exceptions (expected or otherwise) are thrown. For
> long-running operations where locks are desired on a particular row,
> CloudStack does not use native row locking but uses a custom locking
> scheme. See here:
> http://support.citrix.com/article/CTX132018
> 
> 
> 
> On 2/14/13 10:46 AM, "benoit lair" <kurushi4000@gmail.com> wrote:
> 
> >However, i already reached the max by default (100) which is not pretty
> >enormous.
> >
> >And i've seen in the manuals downloaded from cloudstack.org that the
> mysql
> >server should be configured with a max connections depending of
> differents
> >elements such as nodes, vms, networks (i don't remember which elemnt
> >exactly, but sure that there is a dependency of the configuration of mysql
> >according to the size of the deployment.
> >
> >So i need to cover the disaster scenarios in order to be sure to apply the
> >good disaster recovery procedures. Also i need to to be sure not to loss
> >datas acording to differents scenarios. The mysql server being the brain
> >of the cloud you build, it must absolutely keeping fully stable.
> >
> >Here are the reasons why i need to know if the code protect (transactions,
> >exception managing loss of connection or crash or querie out of the mysql
> >query cache) againt mysql failures.
> >
> >Si if there is still a doubt, so okay no problem, i will deploy a
> >redundant
> >solution and will consolidate my installation with per example a very big
> >cluster (lot of ram with an expensive configuration) under xcp covering
> >the
> >crash.
> >
> >Regards, Benoit.
> >
> >2013/2/14 Nik Martin <nik.martin@openfra.me>
> >
> >> I'm pretty sure the amount of connections to the DB is very low, even
> >>for a
> >> large scale CS deployment.
> >>
> >> Nik Martin
> >>
> >>
> >>
> >> On Thu, Feb 14, 2013 at 11:44 AM, benoit lair <kurushi4000@gmail.com>
> >> wrote:
> >>
> >> > Per example, if i reach the max connections, does it will compromise
> >>the
> >> db
> >> > and so cs mgmt server ?
> >> >
> >> > 2013/2/14 benoit lair <kurushi4000@gmail.com>
> >> >
> >> > > Okay guys,
> >> > >
> >> > >
> >> > > MariaDB would be an intersting alternative, but concerning the
> >>failures
> >> > > managements ? Cs code does protect the db integrity against mysql's
> >> > (oracle
> >> > > or mariadb one) failures ? Does cs manages transaction so anyway
> >>mysql
> >> > > crashes, i can go sleep  quietly, cs won't have a corrupted
> >>database (a
> >> > > missing record, or a insert not terminated belong 2  tables, so
> >>there
> >> > will
> >> > > missing a record so it will generating bugs (unrecoverable i mean)
> >>of
> >> the
> >> > > platform.
> >> > >
> >> > >
> >> > > Regards, Benoit
> >> > >
> >> > >
> >> > > 2013/2/14 Alexey Zilber <alexeyzilber@gmail.com>
> >> > >
> >> > >> David,
> >> > >>
> >> > >> I have CS 3 running with MariaDB 5.2.  I'll have to test with
CS 4
> >>and
> >> > the
> >> > >> latest MariaDB though.  A lot of the Oracle enterprise features
> >>are in
> >> > the
> >> > >> latest version.  Without the Oracle pricetag.  Personally I'd
> >>rather
> >> > >> support Monty then Ellison.  :)
> >> > >>
> >> > >> With CS 3, my management server is below minimum specs and still
> >>does
> >> a
> >> > >> decent job.  It's subjective though.
> >> > >>
> >> > >> -Alex
> >> > >> On Feb 14, 2013 11:10 PM, "David Nalley" <david@gnsa.us>
wrote:
> >> > >>
> >> > >> > On Thu, Feb 14, 2013 at 10:07 AM, Alexey Zilber <
> >> > alexeyzilber@gmail.com
> >> > >> >
> >> > >> > wrote:
> >> > >> > > CS should really switch to and recommend MariaDB instead
of
> >> straight
> >> > >> > mysql.
> >> > >> > >
> >> > >> > > You will find your hardware goes much farther with it.
> >> > >> > >
> >> > >> > > -Alex
> >> > >> >
> >> > >> > While I am not personally a mysql fan, I'd love to hear your
> >> > >> > experiences with MariaDB and CloudStack.
> >> > >> >
> >> > >> > --David
> >> > >> >
> >> > >>
> >> > >
> >> > >
> >> >
> >>


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