Re: IO scheduler recommendation

Ron wrote:
> Isn't the use of NFS pretty high on the "things not to do with Postgres" list?

There is a strong sentiment against PostgreSQL on NFS, voiced by people
I tend to trust, but the only detailed horror story I have heard is about
a "bg" mounted NFS file system that wasn't mounted yet when PostgreSQL
was started, and the startup script decided to run "initdb", during which
the mount finally succeeded.

If you browse the archives you will read that "NFS is unreliable" and
"it depends on the implementation, but Linux' implementation is bad"
and such, but without any technical detail ever being mentioned.

That may not be the fault of the people who propagate these opinions -
perhaps they experienced database corruption using NFS, but don't know
exactly which part of NFS caused the problem exactly how.

There are some other voices that say that it works just fine, if you
configure it properly.

The feeling I get from all this is that it is an experimental field,
and everybody who wants to use it would be well advised to run tests
covering all kinds of crash scenarios under load.

I'd still be curious to know if there is someone who can supply
technical details about what *exactly* is wrong with NFS.

Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com