maria-discuss team mailing list archive

[Guillaume Lefranc <guillaume.lefranc@xxxxxxxxxxx>]

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 - script kiddie and computer technician
>> Bertrand Caplet, Flers (FR)
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> --
> Guillaume Lefranc
> Remote DBA Services Manager
> MariaDB Corporation
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-- 
Guillaume Lefranc
Remote DBA Services Manager
MariaDB Corporation