From mboxrd@z Thu Jan 1 00:00:00 1970 From: Justin Maggard Subject: Re: Sysfs update frequency Date: Tue, 16 Mar 2010 15:25:06 -0700 Message-ID: <150c16851003161525g50e09917rfa9b53be3a500978@mail.gmail.com> References: <150c16851003161432gf38c0f5o1cc957435efd4c3e@mail.gmail.com> <20100317085256.6caee9bb@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20100317085256.6caee9bb@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tue, Mar 16, 2010 at 2:52 PM, Neil Brown wrote: > On Tue, 16 Mar 2010 14:32:55 -0700 > Justin Maggard wrote: > >> I've noticed on recent kernels that /sys/block/md?/md/sync_completed >> seems to rarely get updated. =A0What is the expected update interval= ? >> For me, it seems to only update about once every 6% or so during the >> resync. =A0Of course, /proc/mdstat has the actual current progress. > > The expected update time is every 6% - actually 1/16 which is 6.25%. > > sync_completed includes a guarantee that all blocks before this point= really > have been processed. =A0The number in /proc/mdstat is less precise. =A0= The much > of the array has been resynced, but due to the possibility of out-of-= order > completion of writes they may not be a contiguous series of blocks. > > Providing the guarantee (which is needed for externally-managed metad= ata) > requires briefly stalling the resync, so I didn't want to do it more = often. > I could possibly make it time-bases instead of size-based though. > > Is this a problem for you? > Thanks for the info. No, it's not much of a problem, really. Just seemed strange that an array of 2TB disks could resync for an hour with no update to sync_completed. I thought I remembered older kernels updating a lot more frequently, but I could be wrong about that. So I take it that point is where the resync would resume if the system was rebooted? -Justin -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html