[Info-vax] Databases versus RMS

[Arne Vajhøj]

On 4/17/2012 2:52 PM, JF Mezei wrote:
> A web forum has been down for over 24 hours now because of a power
> failure. Seems their database "broke".
>
> Since there are few teenagers here,

One of VMS'es problems.

>                                     I figured I might get some "senior"
> opinions.
>
> Are database engines so fragile that a power failure will truly wreak
> havok on a database requiring time consuming work and debugging ?

No.

In almost all cases the database will recover based on its log.

But whenever there is software involved there is always the
possibility of hitting a software bug.

> Or is this more of a question of young inexperienced web geeks setting
> up some forum software without selecting the right database options and
> not realising that letting a database keep everything in cache (writing
> later when it has time) is a recipe for disaster ?

Data pages are supposed to be write back. Log pages are supposed
to be write through.

But even if log pages are lost, then I would expect the database
to be able to recover.

Arne