Re: Checkpoint Err on Startup of Rsynced System - Mailing list pgsql-general

Scott,
Thanks.  If I understand you correctly..   Actually, we did have M1 shutdown when the inital clone was done (some weeks ago).  That was done using the VMWare system, not rsync.  My main problem is that I don't have WAL archiving setup yet  (I've not changed the Postgres defaults on this so far).  That's part of what the new machine M2 is for.. to practice doing this before adjusting our production machine (M1).   As regards doing a snapshot, I thought that the manual 'CHECKPOINT' would take care of it.

So, this time around I may try to do a manual (initdb.. & pg_restore from backup files) on the new machine in order to get a roughly equivalent installation going.   One early goal I have is to get archiving setup & working at beyond the minimal level.

Jim Longwill

On 05/31/2016 11:50 AM, Scott Mead wrote:

On Tue, May 31, 2016 at 1:13 PM, Jim Longwill <longwill@psmfc.org> wrote:

I am trying to setup a 2nd, identical, db server (M2) for development and I've run into a problem with starting up the 2nd Postgres installation.

Here's what I've done:
  1) did a 'clone' of 1st (production) machine M1 (so both machines on Cent OS 7.2)
  2) setup an rsync operation, did a complete 'rsync' from M1 to M2
  3) did a final 'CHECKPOINT' command on M1 postgres
  4) shutdown postgres on M1 with 'pg_ctl stop'
  5) did final 'rsync' operation  (then restarted postgres on M1 with 'pg_ctl start')
  6) tried to startup postgres on M2

It won't start, & in the log file gives the error message:
...
< 2016-05-31 09:02:52.337 PDT >LOG:  invalid primary checkpoint record
< 2016-05-31 09:02:52.337 PDT >LOG:  invalid secondary checkpoint record
< 2016-05-31 09:02:52.337 PDT >PANIC:  could not locate a valid checkpoint record
< 2016-05-31 09:02:53.184 PDT >LOG:  startup process (PID 26680) was terminated by signal 6: Aborted
< 2016-05-31 09:02:53.184 PDT >LOG:  aborting startup due to startup process failure

I've tried several times to do this but always get this result.  So, do I need to do a new 'initdb..' operation on machine M2 + restore from M1 backups?  Or is there another way to fix this?

You should have stopped M1 prior to taking the backup.  If you can't do that, it can be done online via:

1. Setup archiving
2. select pg_start_backup('some label'); 
   
3. <run rsync>
4. select pg_stop_backup();

  Without archiving and the pg_[start|stop]_backup, you're not guaranteed anything.  You could use an atomic snapshot (LVM, storage, etc...), but it's got to be a true snapshot.  Without that, you need archiving + start / stop backup.

Last section of: https://wiki.postgresql.org/wiki/Simple_Configuration_Recommendation#Physical_Database_Backups will take you to: https://www.postgresql.org/docs/current/static/continuous-archiving.html

--Scott

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Jim Longwill
PSMFC Regional Mark Processing Center
JLongwill@psmfc.org
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Scott Mead
Sr. Architect
OpenSCG

http://openscg.com