From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Riemer Subject: Reason for md raid1 max_sectors_kb limited to 127? Date: Mon, 07 May 2012 11:41:43 +0200 Message-ID: <4FA798D7.4070506@profitbricks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi list, I'm wondering why max_sectors_kb is set to 127 with md raid1. This value is at 512 on normal HDDs. If I do a file copy on ext4 on a normal HDD then I can see with blktrace/blkparse that 128 KiB chunks are read and 512 KiB chunks are written. With md raid it looks like this: 124 KiB, 4 KiB, 124 KiB, 4 KiB, ... . This looks very inefficient. So, is there a particular reason that max_sectors_kb is set to 127? Cheers, Sebastian --=20 Sebastian Riemer Linux Kernel Developer ProfitBricks GmbH Greifswalder Str. 207 10405 Berlin, Germany Tel.: +49 - 30 - 60 98 56 991 - 303 =46ax: +49 - 30 - 51 64 09 22 Email: sebastian.riemer@profitbricks.com Web: http://www.profitbricks.com/ Sitz der Gesellschaft: Berlin Registergericht: Amtsgericht Charlottenburg, HRB 125506 B Gesch=E4ftsf=FChrer: Andreas Gauger, Achim Weiss -- 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