From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Freemyer Subject: Re: [PATCH] barrier support for other md/raid levels Date: Fri, 18 Sep 2009 14:38:36 -0400 Message-ID: <87f94c370909181138g197be2fegd4032778ca6d3351@mail.gmail.com> References: <19123.9980.940255.937839@notabene.brown> <4AB372BA.6020101@redhat.com> <4D87015385157D4285D56CA6101072FF26C2CCB1@exchange07.valvesoftware.com> <4AB3D148.3060607@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <4AB3D148.3060607@redhat.com> Sender: linux-raid-owner@vger.kernel.org To: Ric Wheeler Cc: Chris Green , Neil Brown , "linux-raid@vger.kernel.org" , Mike Snitzer , Tom Coughlan List-Id: linux-raid.ids On Fri, Sep 18, 2009 at 2:28 PM, Ric Wheeler wrote: > On 09/18/2009 02:19 PM, Chris Green wrote: >> >> It seems like what you'd need to robustly test barriers is some sort of >> barrier-supporting loopback device, which >> acted correctly with barriers, but had worst-case behavior without them >> (buffering things for random arbitrarily long periods of time, >> performing all operations in random order, etc). >> >> >> > > I think that it is pretty easy to get corruption (defined as fsck issues) if > we have non-working barriers and do power fail testing. It is a bit tricky > to automate that though but we are working on it, > > ric Ric, You are probably already using them to help automate the process, but if you don't know computer controlled power switches are pretty standard fare for computer clusters. I'm sure Redhat's cluster team has some. And the cluster team may also have scripts to test things like unexpected power fails to one of the cluster members. It may not be too hard to adjust those scripts to handle your needs. Greg