postgresql_disk_filling_report/intervention.md

# intervention 20231027

## Troubleshoot
My first action was check the shared drive where `archive_commad` is supposed to be sending _WAL_ files (archivelog): `\\10.6.1.3\archivelog`.  
That share does *not* exist anymore.  
I check both servers for the existance of such drive and noone of them has that share.  


## first solution implementation
Then I look for a place to write archivelogs, I saw that servers have a `R:\` drive with plenty of space.  
So I decided to use a cross copy between both servers, that is:  
  * Primary will copy to backup as: `\\10.6.1.3\R$\postgresql`
  * Backup will copy to primary as: `\\10.6.0.3\R$\postgresql`

Using that approach it's a best practice to get archived from each other, and solve switchover/failover issues in the future.  

Then I tried adding a network drive, mapping the shared `R:\` in to `Z:\` as:
  * primary's `Z:\` as: `\\10.6.1.3\R$\postgresql`
  * backup's `Z:\` as : `\\10.6.0.3\R$\postgresql`

My idea at that stage was have a unique `postgresql.conf` because `archive_command` will be the same for both servers:  
```conf
archive_command = 'copy "%p" "Z:\\archivelog\\%f"'
```

This setting also create a good configuration, We will not care about switchover/failover in terms of config changes.  


## The problem

I perform all my tests on the _backup_ server.  

Summary: No matter which command I set on `postgresql.conf->archive_command`, postgresql report *Permission Denied* .

I try all the options I can imagine:
  * My prefered solution using `Z:\`
  * Direct copy to `\\10.6.0.3\R$`
  * Add a new shared drive on the _primary_, for example I shared `\\10.6.0.3\postgresql`
  * Grant permissions to `network service` windows "user"
  * Grant permissions to `Everyone` windows group.
  * Combinations of the above options

Until I run out of options.  
Of course when I copied the file via powershell with the Admin user, it worked. All the time.  
So I'm sure the problem comes from the user which runs PostgreSQL service, I had faced similar problems in the past.  
The problem is that I'm not a windows admin, my knowledge is limited here, I tried everything I could think, but maybe a windows sysadmin will know how to solve that permission problem.


## Current config

It was late for me so I decide to do a temporary solution.  
What I did was creaete a local folder on both servers:
```
R:\postgresql\local\archivelog
```

And use:
```conf
archive_command = 'copy "%p" "R:\\postgresql\\local\\archivelog\\%f"'
```

So both _primary_ and _backup_ could execute `archive_command` without problems.  

That is far from a recommended practice but solves the `archive_command` to be failing all the time.  
As a consequence, PostgreSQL should start removing _WAL_ files from `pg_wal`.  

I had to restart the _primary_ server to apply that config, sorrry for that.

## To be done

### Option #1 for archiving (recommended)

As I say, this is far to be a good solution.  
In my opinion, the best option will be the one I already mention, map one network drive from one server to the other into `Z:\` and use:
```conf
archive_command = 'copy "%p" "Z:\\archivelog\\%f"'
```

We should investigate permissions for this solution.

### Option #2 for archiving

In the case we can't achieve the #1 solution, I suggest to keep the current configuration and perform the synchronization via _scheduled_ tasks.  
So, for example, we will launch `rsync R:\postgresql\local\archivelog 10.6.x.3\R:\postgresql\archivelog` (the syntax will be wrong, I had never used `rsync` on windows...).  
To copy archivelogs from one server to the opposite.  


### Additional steps for any solution

#### Archivelog cleanup

A scheduled tasks should be deployed on both _primary_ and _bakcup_ server to keep the side of the _archivelog_ folder under control.  
For example, using [this](https://jackworthen.com/2018/03/15/creating-a-scheduled-task-to-automatically-delete-files-older-than-x-in-windows/) solution.  
The folder to cleanup will be:  
```
R:\postgresql\local\archivelog
```

Or if we achieve the `Z:\` drive solution:
```
R:\postgresql\archivelog
```








## old
I modified postgresql.conf so archivecommand is:
archive_command = 'copy "%p" "Z:\\archivelog\%f

```conf
#archive_command = 'copy "%p" "\\\\10.6.1.3\\\archivelog\\%f"'		# command to use to archive a logfile segment
archive_command = 'copy "%p" "\\\\10.6.1.3\\\R\$\\postgresql\\archivelog\\%f"'
#archive_command = 'copy "%p" "Z:\\archivelog\\%f"'
#archive_command = 'copy "%p" "R:\\postgresql\\local\\archivelog\\%f"'
```

I tried many options but nothing works, it was related to windows permissions. I tried copying from the powershell with admin user and the copy from one server to the other worked.
I tried adding permissions (as much as I could remember) but nothing worked.

So At the end I decided to archive locally on "R:"

So both server are archiving into "R:\postgresql\local\archivelog"

I restarted the master instance of postgresql because of this, to apply the new setup.