Re: Initdb --data-checksums by default

On 20.04.2016 11:40, Andreas Joseph Krogh wrote:
> På onsdag 20. april 2016 kl. 10:33:14, skrev Alex Ignatov
> <a(dot)ignatov(at)postgrespro(dot)ru <mailto:a(dot)ignatov(at)postgrespro(dot)ru>>:
>
>
>
> On 20.04.2016 11:29, Devrim Gündüz wrote:
> > Hi,
> >
> > On Wed, 2016-04-20 at 10:43 +0300, Alex Ignatov wrote:
> >> Today in Big Data epoch silent data corruption becoming more
> and more
> >> issue to afraid of. With uncorrectable read error rate ~ 10^-15 on
> >> multiterabyte disk bit rot is the real issue.
> >> I think that today checksumming data must be mandatory set by
> default.
> >> Only if someone doesn't care about his data he can manually
> turn this
> >> option off.
> >>
> >> What do you think about defaulting --data-checksums in initdb?
> > I think this should be discussed in -hackers, right?
> >
> > Regards,
> May be you right but i want to know what people think about it before
> i'll write to hackers.
>
> -1 on changing the default.
> 10^15 ~= 1000 TB, which isn't very common yet. Those having it
> probably are aware of the risk and have enabled checksums already.
> --
> *Andreas Joseph Krogh*
> CTO / Partner - Visena AS
> Mobile: +47 909 56 963
> andreas(at)visena(dot)com <mailto:andreas(at)visena(dot)com>
> www.visena.com <https://www.visena.com>
> <https://www.visena.com>
It is per bit not bytes. So it is ~100 TB. We working with some
enterprise who have WALs creation rate ~ 4GB per min - so it is only max
100 days before you get bit rotted and have probability to get silent
data corruption.
Also don't forget that it is theoretical limit and Google tells us that
HDD and SSD is not as reliable as manufactures tell. So this 10^-15 can
easily be much higher.

--
Alex Ignatov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company