Re: [GENERAL] Recover corrupted data

On Wed, 19 Apr 2017 13:25:41 -0300, Alexandre <psybox@gmail.com>
wrote:

>  :
>But there is no solution for [file corruption]?


The only solutions are to guard against it: make frequent backups and
make use of safety mechanisms in Postgresql and in the OS.

Postgresql logs (WAL) intended changes to the database before it makes
them.  NTFS *can* do similar change logging for files - but its
logging may or may not be turned on by default.


If you are using NTFS on a hard disk, then for maximum crash
resistance make sure that both journaling (usn) and self-healing
(repair) are turned on.

If the hard disk was formatted by a (relatively) recent version of
Windows, then it is likely that journaling is on already.  But best to
check because prior to Vista the default was OFF, and a number of
internet "tweak" sites advise to turn off journaling deliberately to
enhance write performance.  Disabling journaling is [maybe] acceptable
for a personal workstation, but not for a server.


If you are using SSD, then OS journaling will be off by default.  If
the SSD is battery backed, then journaling *probably* is not necessary
and you can choose whether to trade enhanced crash resistance against
increased SSD wear and (slightly) reduced write performance.


See:

fsutil usn ...
https://technet.microsoft.com/en-us/library/cc788042(v=ws.11).aspx

fsutil repair ...
https://technet.microsoft.com/en-us/library/ff621565(v=ws.11).aspx


George