From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mario 'BitKoenig' Holbe Subject: Re: No syncing after crash. Is this a software raid bug? Date: Fri, 3 Mar 2006 16:10:51 +0100 Message-ID: References: <20060301124432.GA3591@hactar.lan> <20060301215641.GA27042@hactar.lan> <20060303073016.GA662@hactar.lan> <20060303144824.GA15672@hactar.lan> Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Kasper Dupont <87385155133026632046@expires.04.sep.2006.kasperd.net> wrote: > On the 2.6 system where I see the differences between mirrors > /proc/ide/hde/settings:wcache 1 write cache enabled. Btw... don't disable it on a production system without previously thinking about it :) Disabling write cache leads to massive performance decrease on heavy simultaneous I/O... On a system with (IMHO not heavy but significant) simultaneous I/O I got 35MB/s write speed on dd with write cache enabled and it shrunk down to 9MB/s with write cache disabled - while load grew up from ~0 to ~8. > On a 2.4 system where I see no differences between mirrors I > /proc/ide/hde/settings:wcache 0 0 1 rw > So how should I interpret this? As I said - on 2.4 write cache reporting through /proc is broken: it always reports disabled write cache, while it is not necessarily disabled. Use hdparm -I instead (big I, not small i). regards Mario -- "Why are we hiding from the police, daddy?" | J. E. Guenther "Because we use SuSE son, they use SYSVR4." | de.alt.sysadmin.recovery