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

[Tomonari K. <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