Date: Wed, 5 May 2010 16:44:51 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: Dominic Fandrey <kamikaze@bsdforen.de> Cc: freebsd-stable@freebsd.org Subject: Re: geom_sched influence on SU consistency Message-ID: <AANLkTikT9xO4_SnDCbx1ANJ6j-GKNCsXhcmVmr-mGBx4@mail.gmail.com> In-Reply-To: <4BE17191.6040305@bsdforen.de> References: <4BE17191.6040305@bsdforen.de>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, May 5, 2010 at 3:24 PM, Dominic Fandrey <kamikaze@bsdforen.de> wrote: > I'm wondering how geom_sched influences soft-update consistency. > > To my understanding it's very important to SU, that the file system > controls writing sequences. Because geom_sched is transparent, > i.e. UFS does not know about access scheduling, I'm afraid that > the use of geom_sched would endanger my file system consistency > in case of a crash. > > Can anyone put my fears to rest or confirm them? geom_sched is no different from the standard (elevator) disk scheduler or tagged queueing -- these system may already serve queued requests out of order. if a client wants to enforce a specific ordering of requests it can easily do so by waiting the completion of a previous request before issuing a new one.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?AANLkTikT9xO4_SnDCbx1ANJ6j-GKNCsXhcmVmr-mGBx4>