From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [RFC] [DRAFT] [udev PATCH] First attempt at vendor RAID support in 2.6 Date: Wed, 21 Apr 2004 13:34:35 -0400 Sender: linux-raid-owner@vger.kernel.org Message-ID: <4086B0AB.1030604@pobox.com> References: <40803C61.503@gmx.net> <40816AEC.6020309@gmx.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <40816AEC.6020309@gmx.net> To: Carl-Daniel Hailfinger Cc: Linux Kernel Mailing List , Thomas Horsten , medley@lists.infowares.com, linux-hotplug-devel@lists.sourceforge.net, Wilfried Weissmann , Bartlomiej Zolnierkiewicz , Greg KH , Linux RAID Mailing List , Martins Krikis , ataraid-list@redhat.com, linux-scsi@vger.kernel.org List-Id: linux-raid.ids Carl-Daniel Hailfinger wrote: > since on one side ATARAID support has vanished from 2.6 and on the other > side some parties are pushing for an enhanced MD driver in the kernel, why > don't we do the setup and metadata handling of all those types of RAID in > userspace? > > I got positive feedback by private mail from several kernel developers for > the last incarnations of raiddetect, so if you disagree, speak up now. > > Raiddetect is a program to find vendor software RAID superblocks, analyze > them for validity, group them by RAID vendor and (later on) set them up > via MD/DM. It is small (~35kB compiled statically against klibc) and > designed to be run from initrd/initramfs. > > raiddetect now supports the following metadata formats: > -Promise RAID > -Highpoint RAID > -Medley RAID > -Intel RAID Yeah, it's pretty spiffy. I like it. My personal preference for raiddetect would be as a simple helper that examines the system, and outputs some information. Then, someone using device mapper could use that in a script that takes the information generated by raiddetect, and uses it to configure DM-based raid0 and raid1 arrays. Small and purpose-specific, and even usable for someone in a 2.4.x kernel that wrote a small MD-based plugin for "userspace-configured vendor raid [01]" > If you want support for another metadata format, please tell me which and > I'll try to add it. Patches are preferred ;-) My current wishlist is: > - Adaptec ASR HostRAID > - DDF RAID > > Hot-add and hot-remove features can be added easily if raiddetect is > called by an udev rule on block device removal/insertion. If raiddetect > stays loaded into memory or is allowed to save its state, hotplug events > will not trigger any access to devices not related to that particular RAID > array. Well, hotplug and hotremove are more interrupt-context type events these days. It's feasible to send "device just appeared" or "device is already gone, nyah nyah" messages to /sbin/hotplug after that fact, mainly. Failover and hotplug/hotremove callbacks are definitely in-kernel things, IMO. Userspace drives the policy behind that, of course. > It seems that there are some host adapter drivers out there implementing > their own RAID engine which could be consolidated into a single RAID > "library" instead. If you know about such drivers, please speak up. In the kernel long term, I would definitely like to see just a single piece of code for each raid flavor -- RAID0, 1, 5, 6, etc. Jeff