From: Mike Mestnik Subject: How to use mkfs.ext4 "stride=" on RAID correctly? Date: Wed, 13 Jan 2010 18:13:12 -0600 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE To: linux-ext4@vger.kernel.org Return-path: Received: from ey-out-2122.google.com ([74.125.78.27]:11212 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755186Ab0ANANN convert rfc822-to-8bit (ORCPT ); Wed, 13 Jan 2010 19:13:13 -0500 Received: by ey-out-2122.google.com with SMTP id 22so25119eye.19 for ; Wed, 13 Jan 2010 16:13:12 -0800 (PST) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: What should this value be? =A0From what I gather it should be the lengt= h of data stored on a single disk for each RAID level block. =A0If that's the case how is it that two given data blocks are calculated to be on separate drives? =A0It seams to me that the stripe-width is also essential in this regard, but the man page does not reflect this. =46or example let's say that stride=3D1, then which of the following blocks are not on the same drive as 1: 8 9 10? The answer is dependent on the number data disks, like so. Where x =3D n - 1 or n depending on the RAID type. if x =3D 2 then 9 if x =3D 3 then 8 and 10 if x =3D 5 then 8 and 9 There is no way to make this calculation with out knowing x, further more calculating x based of of both stride and stripe-width is round about... =A0Why not simply ask for x, the number of data disks and have stripe-width be the value that is calculated, as stride might not go into stripe-width evenly leaving you with a headache. Did I locate a bug? Is there a better forum for this discussion? -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html