Subject: Re: Read policy on RAIDframe mirror devices
To: Matthias Scheler <email@example.com>
From: Greg Oster <firstname.lastname@example.org>
Date: 12/11/2003 10:15:27
Matthias Scheler writes:
> if I have a RAIDframe mirror devices called "raid0e" which is sitting
> on top of "wd0e" and "wd1e" how will reads be done:
> 1.) Always from "wd0e"?
> 2.) Interleaved from "wd0e" and "wd1e"?
> 3.) Depending on the order in "/etc/raid0.conf"?
"some of the above" :) The reads will typically be done from
whatever component RAIDframe figures it can get the data from the
fastest. It esitmates this by simply selecting the component that
has the shortest I/O disk queue at the time of the I/O.
See: rf_dagutils.c:rf_SelectMirrorDiskIdle() for the gory details.