Re: Warm standby can't start because logs stream too quickly from the master

[Zach Walton]

This was my fault. I'd restored recovery.conf from recovery.done to try to
recover manually after automated recovery failed. Everything's working
after stopping the database and running pgpool online recovery again.

Thanks for the help.

On Sat, Dec 2, 2017 at 1:55 PM, Joshua D. Drake 
wrote:

> On 12/02/2017 11:02 AM, Zach Walton wrote:
>
>>
>> Generally this works itself out if I wait (sometimes a really long time).
>> Is there a configuration option that allows a warm standby to start without
>> having fully replayed the logs from the master?
>>
>> * Note: wal_keep_segments is set to 8192 on these servers, which have
>> large disks, to allow for recovery within a couple of hours of a failover
>> without resorting to restoring from archive
>> * This is specifically an issue for pgpool recovery, which fails if a
>> standby can't start within (by default) 300 seconds. Open to toggling that
>> param if there's no way around this.
>>
>
> It needs to only reach a consistent state, it doesn't need restore all
> logs. What does your recovery.conf say and are you *100% sure% you issued a
> pg_stop_backup()?
>
> JD
>
>
>
> --
> Command Prompt, Inc. || http://the.postgres.company/ || @cmdpromptinc
>
> PostgreSQL Centered full stack support, consulting and development.
> Advocate: @amplifypostgres || Learn: https://pgconf.org
> * Unless otherwise stated, opinions are my own.   *
>
>

Re: Warm standby can't start because logs stream too quickly from the master

[Jeff Janes]

On Sat, Dec 2, 2017 at 11:02 AM, Zach Walton  wrote:

> Looking at the startup process:
>
> postgres 16749  4.1  6.7 17855104 8914544 ?Ss   18:36   0:44 postgres:
> startup process   recovering 00085B1C0030
>
> Then a few seconds later:
>
> postgres 16749  4.2  7.0 17855104 9294172 ?Ss   18:36   0:47 postgres:
> startup process   recovering 00085B1C0047
>
> It's replaying logs from the master, but it's always a few behind, so
> startup never finishes. Here's a demonstration:
>
> # while :; do echo $(ls data/pg_xlog/ | grep -n $(ps aux | egrep "startup
> process" | awk '{print $15}')) $(ls data/pg_xlog/ | wc -l); sleep 1; done
> # current replay location # number of WALs in pg_xlog
> 1655:00085B1C0064 1659
> 1656:00085B1C0065 1660
> 1658:00085B1C0067 1661
> 1659:00085B1C0068 1662
> 1660:00085B1C0069 1663
>
> Generally this works itself out if I wait (sometimes a really long time).
> Is there a configuration option that allows a warm standby to start without
> having fully replayed the logs from the master?
>


Warm standbys aren't supposed to start up, that is what makes them warm.
Are you trying to set up a hot standby?  Are you trying to promote a warm
standby to be the new master (but usually you would do that when the
current master has died, and so would no longer be generating log.)

Cheers,

Jeff

Re: Warm standby can't start because logs stream too quickly from the master

[Joshua D. Drake]

On 12/02/2017 11:02 AM, Zach Walton wrote:


Generally this works itself out if I wait (sometimes a really long 
time). Is there a configuration option that allows a warm standby to 
start without having fully replayed the logs from the master?


* Note: wal_keep_segments is set to 8192 on these servers, which have 
large disks, to allow for recovery within a couple of hours of a 
failover without resorting to restoring from archive
* This is specifically an issue for pgpool recovery, which fails if a 
standby can't start within (by default) 300 seconds. Open to toggling 
that param if there's no way around this.


It needs to only reach a consistent state, it doesn't need restore all 
logs. What does your recovery.conf say and are you *100% sure% you 
issued a pg_stop_backup()?


JD



--
Command Prompt, Inc. || http://the.postgres.company/ || @cmdpromptinc

PostgreSQL Centered full stack support, consulting and development.
Advocate: @amplifypostgres || Learn: https://pgconf.org
* Unless otherwise stated, opinions are my own.   *

Warm standby can't start because logs stream too quickly from the master

[Zach Walton]

Looking at the startup process:

postgres 16749  4.1  6.7 17855104 8914544 ?Ss   18:36   0:44 postgres:
startup process   recovering 00085B1C0030

Then a few seconds later:

postgres 16749  4.2  7.0 17855104 9294172 ?Ss   18:36   0:47 postgres:
startup process   recovering 00085B1C0047

It's replaying logs from the master, but it's always a few behind, so
startup never finishes. Here's a demonstration:

# while :; do echo $(ls data/pg_xlog/ | grep -n $(ps aux | egrep "startup
process" | awk '{print $15}')) $(ls data/pg_xlog/ | wc -l); sleep 1; done
# current replay location # number of WALs in pg_xlog
1655:00085B1C0064 1659
1656:00085B1C0065 1660
1658:00085B1C0067 1661
1659:00085B1C0068 1662
1660:00085B1C0069 1663

Generally this works itself out if I wait (sometimes a really long time).
Is there a configuration option that allows a warm standby to start without
having fully replayed the logs from the master?

* Note: wal_keep_segments is set to 8192 on these servers, which have large
disks, to allow for recovery within a couple of hours of a failover without
resorting to restoring from archive
* This is specifically an issue for pgpool recovery, which fails if a
standby can't start within (by default) 300 seconds. Open to toggling that
param if there's no way around this.