[Info-vax] Databases versus RMS

[Neil Rieck]

On Apr 17, 2:52 pm, JF Mezei <jfmezei.spam... at vaxination.ca> 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, 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 ?
>
> 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 ?

I think this has more to do with cache settings (both hard and soft).
Older systems (UNIX and VMS to only name two) avoided horrible I/O
write times by doing a delayed write-back rather than a write-through.
It has been a while since I worked on Solaris-8, but I seem to
remember that a dirty (i.e. changed) directory might not be written
back to disk for up to 29 seconds. So if the system crashed before the
write-back, you would usually loose something. Remembering that there
is no such thing as a free lunch, booting a Solaris system took way
longer. Part of the delay was due to disk scans which sometimes
stopped (a this point you needed to manually run "fdisk").

Just my 2-cents from faulty wetware memory :-)

NSR