From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Sysfs update frequency Date: Wed, 17 Mar 2010 08:52:56 +1100 Message-ID: <20100317085256.6caee9bb@notabene.brown> References: <150c16851003161432gf38c0f5o1cc957435efd4c3e@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <150c16851003161432gf38c0f5o1cc957435efd4c3e@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Justin Maggard Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids 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. What is the expected update interval? > For me, it seems to only update about once every 6% or so during the > resync. Of 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. The number in /proc/mdstat is less precise. 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 metadata) 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? NeilBrown