maria-discuss team mailing list archive

[Tom Worster <fsb@xxxxxxxxxx>]

Hi Guillaume,

What variable(s) should we monitor to estimate the rate at which gcache is
written? or to otherwise estimate how far back a given gcache.size goes in
history?

Tom


From:  Maria-discuss
<maria-discuss-bounces+fsb=thefsb.org@xxxxxxxxxxxxxxxxxxx> on behalf of
Guillaume Lefranc <guillaume.lefranc@xxxxxxxxxxx>
Date:  Saturday, December 5, 2015 at 10:23 AM
To:  Bertrand Caplet <bertrand.caplet@xxxxxxxxxx>, maria-discuss email list
<maria-discuss@xxxxxxxxxxxxxxxxxxx>
Subject:  Re: [Maria-discuss] Most reliable SST (or IST ?) method for
MariaDB Cluster

Hi Bertrand,

You don't want your partitioned node to do SST, because IST is obviously
faster.
IST should always happen, unless the node has lost state (crash,
inconsistent data, etc) or the latest writeset is not found in the galera
cache.
So, rule of thumb is to have a galera cache big enough, so it can hold the
latest writesets while your node is partitioned.
Galera cache (the name is a bit misleading, it's more like a binary log) is
just a file on disk, so the limitation is about disk space only.
Set it like this: wsrep_provider_options="gcache.size=5G"

About xtrabackup methods. the legacy xtrabackup method should not be used
anymore, as it is deprecated because of many bugs/issue.
Use xtrabackup-v2 in all cases. You can improve the method by setting some
[xtrabackup] options in your my.cnf file, such as:

# Enables compression, requires qpress package
compress
# Enables parallel transfers (n=number of threads)
parallel=n

xtrabackup-v2 method does not lock the donor database while it is
processing, so it can be used for "hot" SST (on the contrary, rsync needs a
global lock)

Regards,

On Sat, Dec 5, 2015 at 2:46 PM Bertrand Caplet <bertrand.caplet@xxxxxxxxxx>
wrote:
> Hi all,
> I'm using MariaDB Cluster with 3 servers and I often have split brain
> because of network. When a network split brain happen, only one node is
> disconnected.
> What is for you the best choice for SST or maybe IST method for this
> configuration ? (N.B.: I already tried rsync method but i'm not really
> satisfied with it).
> 
> I have another question, I tried xtrabackup-v2 but it seems this method
> can't be use for bootstrapping while database is on. Does xtrabackup
> method can do this ?
> 
> Regards,
> 
> --
> CHUNKZ.NET <http://CHUNKZ.NET>  - script kiddie and computer technician
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-- 
Guillaume Lefranc
Remote DBA Services Manager
MariaDB Corporation
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