Re: PostgreSQL File System Based Backup Restartability

girish R G peetle <giri.anamika0@gmail.com> writes:

> Thanks Kevin.
>
> "Be careful that when you resume after such an interruption you do
> not skip any files and that you complete or re-copy any files that
> were partially copied before the problems."
>
> Here you mean, we should not skip any files that was already backed up before interruption ?
>  I will have to backup entire content under DATA directory again ?

False.

Any file already copied and known copied thoroughly should not require
copying again.

The file under copy when the network drop occurred needs copying again
and/or  syncing if your copy program knows how to do that without moving
all bits... and of course all missing files  need copying also.

HTH

> Thanks
> Girish
>
> On Tue, Feb 17, 2015 at 10:04 PM, Kevin Grittner <kgrittn@ymail.com> wrote:
>
>     girish R G peetle <giri.anamika0@gmail.com> wrote:
>
>     > Steps
>     > - Database size is 1 TB
>     > - I'll execute pg_start_backup('label');
>     > - I will traverse through the DATA directory to get the list of
>     >   directories and files.
>     > - I will start moving the files to backup media. ( over network )
>     > - When I'm half way (500GB done), network error happens. So
>     >   movement of files is halted.
>     > - Network issue is resolve after 30 minutes (In this time files
>     >   might have got deleted or added with creation/deletion of
>     >   database/tables )
>     > - I'll resume moving the files to backup media from where it had
>     >   halted.
>     > - When movement of files is done, I'll execute pg_stop_backup()
>     > - I'll move all the transaction logs that got archived to backup
>     >   media.
>     >
>     > Is PostgreSQL server recovery to a consistent state possible with
>     > backup content obtained from above steps ?
>
>     As long as you follow all the rules for what files to copy (and not
>     copy), you should have a good backup.  Some things to be careful
>     about that I've seen people get wrong with some frequency:
>
>     - Be sure to exclude all files in and under the pg_xlog directory.
>       The backup should contain the directory itself, and it is best to
>       include its subdirectory, but copying the files can cause
>       corruption.
>     - Exclude the postmaster.pid file.
>     - Be sure *not* to exclude the backup_label file.  Without this
>       file, restoring from the backup may or may not have corruption,
>       which may or may not be initially apparent.
>
>     Be careful that when you resume after such an interruption you do
>     not skip any files and that you complete or re-copy any files that
>     were partially copied before the problems.
>
>     --
>     Kevin Grittner
>     EDB: http://www.enterprisedb.com
>     The Enterprise PostgreSQL Company
>

--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consulting@comcast.net
p: 312.241.7800