Re: consistent postgresql snapshot

[Ron <ronljohnsonjr@xxxxxxxxx>]

    On 5/11/22 10:41, Zwettler Markus (OIZ) wrote:

PostgreSQL12 running on CentOS7 + ext4.

 

Would it be save to do a "fsfreeze –freeze" + disk snapshot + "fsfreeze –unfreeze" of the PGDATA filesystem to get a consistent snapshot?

 

I am wondering as PostgreSQL default blocksize = 8k while ext4 default blocksize = 4k, resulting in 2 fs blocks per db block.

    If data/base and pg_xlog are on the same filesystem, then it might
    work.
    
    Be sure to select pg_start_backup('something
      informative'); beforehand, and select
      pg_stop_backup(); afterwards.
    
    For example:
    psql -c "select pg_start_backup('something
      informative');"
      fsfreeze –freeze
    disk snapshot
        fsfreeze –unfreeze
      psql -c "select pg_stop_backup();"

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