maria-discuss team mailing list archive

[Tom Worster <fsb@xxxxxxxxxx>]

Hi Guillaume,

Yes, it helps. Thanks! I can log these every hour (say) and plot the curve
over a week to get an idea of rate and its variability.

Tom

From:  Guillaume Lefranc <guillaume.lefranc@xxxxxxxxxxx>
Date:  Saturday, December 5, 2015 at 12:57 PM
To:  Tom Worster <fsb@xxxxxxxxxx>, 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 Tom,

Use the wsrep_replicated_bytes and wsrep_received_bytes status variables.
The sum of those two variables will give you the total bytes written to
gcache. By using a derivative function you should be able to figure out the
write rate.

Hope this helps,

On Sat, Dec 5, 2015 at 6:46 PM Tom Worster <fsb@xxxxxxxxxx> wrote:
> 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
>> Bertrand Caplet, Flers (FR)
>> Feel free to send encrypted/signed messages
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>> 
>> 
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> -- 
> Guillaume Lefranc
> Remote DBA Services Manager
> MariaDB Corporation
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Guillaume Lefranc
Remote DBA Services Manager
MariaDB Corporation