Обсуждение: Reboot standby

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Reboot standby

От
"Thomas W. Ekberg"
Дата:

We have 2 postgres servers, a primary and standby. One of our DB admins noticed a "health indicator" alert light on our standby which means "system degraded." She logged into the iLO and it lists the Cache Module Status as Failed. This needs to be repaired (we have an idea on what needs to be done) and most likely will require a reboot of our standby server.


We use streaming replication and from what I can see, that is initiated by the standby server. What are the shutdown and restart considerations for our standby server?


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Re: Reboot standby

От
Payal Singh
Дата:
As long as the streaming replication is in asynchronous mode, you can restart the standby anytime without affecting the primary. You can check whether replication is synchronous or asynchronous with "select sync_state from pg_stat_replication;"

If it says 'synchronous', you will have to first change it to asynchronous before you can reboot the standby, or else all commits on primary will be pending waiting for the replica to replicate those commits first


Payal Singh,
Database Administrator,
OmniTI Computer Consulting Inc.
Phone: 240.646.0770 x 253

On Mon, Feb 26, 2018 at 1:07 PM, Thomas W. Ekberg <tekberg@uw.edu> wrote:

We have 2 postgres servers, a primary and standby. One of our DB admins noticed a "health indicator" alert light on our standby which means "system degraded." She logged into the iLO and it lists the Cache Module Status as Failed. This needs to be repaired (we have an idea on what needs to be done) and most likely will require a reboot of our standby server.


We use streaming replication and from what I can see, that is initiated by the standby server. What are the shutdown and restart considerations for our standby server?


1515078413450_PastedImage

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Re: Reboot standby

От
Andreas Kretschmer
Дата:



On 26.02.2018 19:07, Thomas W. Ekberg wrote:
We use streaming replication and from what I can see, that is initiated by the standby server. What are the shutdown and restart considerations for our standby server?
your master has to keep enough wals that the standby can retrieve them and catch up to the master. there are several solutions to achive that. you can define wal_keep_segments or you can use replication slots. other solutions: using archive_command to store the wals outside from the master. you can also use barman as a wal-hub.


Regards, Andreas