Re: Test disk reliability (or HGST HTS721010A9E630 surprisingly reliable)

On Mon, 21 Dec 2015 14:54:14 +0100
Félix GERZAGUET <felix(dot)gerzaguet(at)gmail(dot)com> wrote:

> On Mon, Dec 21, 2015 at 12:31 AM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>
> wrote:
>
> > On 12/20/15 1:09 PM, Félix GERZAGUET wrote:
> >
> >> After reading
> >> http://www.postgresql.org/docs/current/static/wal-reliability.html, I
> >> tried the recommended diskchecker.pl
> >> <http://brad.livejournal.com/2116715.html> but I am not satisfied:
> >>
> >> I always get:
> >> Total errors: 0
> >>
> >> even if I tested with with a HGST HTS721010A9E630 that the vendor's
> >> datasheet
> >> (http://www.hgst.com/sites/default/files/resources/TS7K1000_ds.pdf)
> >> advertise as "
> >> Designed for low duty cycle, non mission-critical applications in
> >> PC,nearline and consumer electronics environments, which vary
> >> application to application
> >> "
> >>
> >> Since it is not, a high end disk, I expect some errors.
> >>
> >
> > Why? Just because a disk isn't enterprise-grade doesn't mean it has to lie
> > about fsync, which is the only thing diskchecker.pl tests for.
> >
>
> I was thinking that since the disk have a 32M write-cache (with not
> battery) it would lie to the OS (and postgres) about when data are really
> on disk (not in the disk write cache). But maybe that thinking was wrong.

It varies by vendor and product, which is why diskchecker.pl exists.
It's even possible that the behavior is configurable ... check to see
if the vendor provides a utility for configuring it.

--
Bill Moran