From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Tue, 03 Jun 2008 15:03:14 -0700 (PDT) Received: from cuda.sgi.com ([192.48.176.15]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id m53M3Baj026254 for ; Tue, 3 Jun 2008 15:03:11 -0700 Received: from rgminet01.oracle.com (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 425901776F3D for ; Tue, 3 Jun 2008 15:04:04 -0700 (PDT) Received: from rgminet01.oracle.com (rgminet01.oracle.com [148.87.113.118]) by cuda.sgi.com with ESMTP id aF0HUKrDMgHcRnZx for ; Tue, 03 Jun 2008 15:04:04 -0700 (PDT) Subject: Re: Questions for article From: "Martin K. Petersen" References: <13033.143.166.226.57.1212526129.squirrel@tomslinux.homelinux.org> Date: Tue, 03 Jun 2008 18:00:42 -0400 In-Reply-To: <13033.143.166.226.57.1212526129.squirrel@tomslinux.homelinux.org> (Thomas King's message of "Tue\, 3 Jun 2008 15\:48\:49 -0500 \(CDT\)") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Thomas King Cc: xfs@oss.sgi.com >>>>> "Thomas" == Thomas King writes: Thomas> -Is XFS fully RAID aware inthat it aligns metadata with RAID Thomas> stripes? Some of the information I see states XFS can get Thomas> geometry information from LVM and MD, but what about hardware Thomas> RAID? The stuff that queries MD/LVM for stripe unit/stripe size has been in XFS for a while[1]. For hardware RAID there is no non-proprietary way to obtain the information from the device. So whoever runs mkfs on a hardware RAID device must manually specify the geometry using the sunit and swidth parameters. That capability has been there since the dawn of time. Note that in the upcoming version of SBC-3 (SCSI Block Commands) finally features a VPD page that the array firmware can fill out to let the operating system know about stripe size, etc. I have been working on a patch that extracts this information and presents it to the block layer in a generic fashion. But so far I have not seen a single array that implements said VPD page. IOW, there hasn't been much motivation to finish that work. Also, SBC-3 is work in progress. The standard has not been ratified yet so things could change before it is released. I doubt they are going to change the block limits VPD, but who knows? Thomas> -Does XFS take advantage of T10 DIF (block protection?)? As I mentioned earlier today, filesystems do not need to be explicitly DIF-aware. I/Os submitted by XFS will be protected if the kernel does DIF. The DIF support has not been accepted upstream yet. Working on that. But in any case DIF-capable hardware is not generally available. [1] http://www.linux.sgi.com/archives/xfs/2001-03/msg00435.html -- Martin K. Petersen Oracle Linux Engineering