Re: [Postgres-xc-developers] I want to know the behavior of GTM/GTM_standby.

[Koichi S. <koi...@gm...>]

A) GTM standby writes its backup (both usual backup and Barrier
backup) at the same timing as GTM master so you don't have to restore
these data from the master to the slave at the failover.   Please note
that usual backup timing may be different from the master and the
slave.   In both cases, backup advances GTM and sequence value from
the current value so they can be used as a restart point.

B) You just restart GTM standby at the same or a different server.
GTM standby will backup master status, writes restart point and then
it continues restart point as A).    Please note that it does not
backup existing Barrier restart points so you may have to backup them
manually.

Regards;
---
Koichi Suzuki


2013/12/27 Tomonari Katsumata <kat...@po...>:
> Hi,
>
> I'm investigating about the behavior of GTM/GTM_standby.
> Because I'm thinking about how making GTM more High Availability.
> To clarify the behavior, I want to understand some things below.
>
> A)When do GTM/GTM_standby write data to their disk?
> Currently I know that GTM writes data in below case.
>
> 1)Stopping GTM
> 2)GXID/Sequence are over the limit
> 3)Executing CREATE BARRIER
>
> Are there another case?
> And then, what timing does GTM_standby write data at?
>
> B)When occurring something wrong against GTM/GTM_standby, how do they work?
>
> a)How does GTM work without write permission on the disk?
> According to the situation 1),2),3), the behavior is changed?
> 1)GTM continues to work(gtm_ctl returns ERROR)
> 2)GTM Stopped abnormally
> 3)GTM continues to work, but backup file is never created
>
> Are there another behavior?
>
> b)How does GTM_standby work without write permission on the disk?
> - GTM_standby will stop abnormally?
> - How GTM_standby work when executing promote in this situation?
>
> regards,
> ---------------
> NTT Software Corporation
> Tomonari Katsumata
>
>
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