From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?iso-8859-1?Q?=22Ramon_Sch=F6nborn=22?= Subject: Re: md device io request split Date: Wed, 23 Nov 2011 14:22:16 +0100 Message-ID: <20111123132216.162860@gmx.net> References: <20111122093634.105520@gmx.net> <20111123133124.2042c1f4@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20111123133124.2042c1f4@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids =20 > RAID1 will only limit requests to 4K if the device beneath it is > non-contiguous - e.g. a striped array or LVM arrangement were consecu= tive > blocks might be on different devices. how does it know if a device is non-contiguous? Is there a way to have = a dm device "marked" like that or force md to use bigger requests? Lets assume a host with about 20 raid1 devices consisting of dm-devices= with the mentioned overhead - do you think that not splitting the requ= ests could lead to a noticeable performance improvement? Thanx for your help, Ramon Sch=C3=B6nborn --=20 Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de -- 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