Re: Raw devices vs. Filesystems

In article <5719(dot)1081315562(at)sss(dot)pgh(dot)pa(dot)us>,
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> But to get back to the point of this discussion: to allow PG to use raw
> devices instead of filesystems, we'd first have to do a ton of
> portability work (since raw disk access is nowhere standard), and
> abandon our principle that Postgres does not run as root (since raw disk
> access is not permitted to non-root processes by any sane sysadmin).

Why not? In MySQL/InnoDB, you do a "chown mysql.daemon /dev/raw/raw1"
(or whatever raw disk you want to access), and that's all.

> After that, we get to implement our own filesystem-equivalent management
> of disk space allocation, disk I/O scheduling, etc. Are we really
> smarter than all those kernel hackers doing this for a living? I doubt it.

Ditto. I don't have hard numbers for MySQL, but I didn't see any
noticeable improvement when messing with raw disks (at least under
Linux).