Re: [RFC] [DRAFT] [udev PATCH] First attempt at vendor RAID supportin 2.6

From: Jeff Garzik
Date: Wed Apr 21 2004 - 12:36:58 EST

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

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

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

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.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at