A developer working on my server has fiddled with some settings and knocked my postgresql database offline. I've been messing with it for an hour and am considering just reinstalling postgresql fresh because I know it will work easily then.

I know this is where I database is. /var/lib/postgresql/9.1/main. Can I copy this file, then paste it back in and expect it to work for me? Its for the same machine and everything.

  • You want to copy PG data directory and paste it to other directory (on the same machine), after that, you will start PG server on new data directory ?
    – Luan Huynh
    Commented Feb 24, 2015 at 1:55

1 Answer 1


Yes, as long as you install version 9.1 (minor version doesn't matter). And normally you don't need to copy/move them anywhere, the installation will notice there is already a database system set up and will use it. Of course taking a backup is never a bad idea.

Then again, the reason for it being offline should be clear from PostgreSQL logs. Memory allocations can be too high, or some other thing, and this is reported in the log.

  • Do you have to stop Postres before copying the folder? I could imagine, that there are some writes in the folder while you copy it. Couldn't this cause a defunctional database? Or inconsistent data?
    – rubo77
    Commented Jan 18, 2017 at 12:12
  • @rubo77 If you just copy the files then yes, it has to be turned off. If you want to clone a live system you have to tell PostgreSQL that you're going to do that so it knows to keep the files consistent while you copy. Commented Jan 18, 2017 at 20:13

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