Wanted: partitionable md devices

Mike Jagdis (mike@roan.co.uk)
Thu, 3 Dec 1998 13:20:23 +0000 (GMT/BST)

I thought I'd just chuck this one in - give someone something
to think about over Christmas perhaps...

I would like to be able to partition md devices. Why? Well, I want
to put two drives on separate controllers in a RAID-0 pair because
that gives me almost double the thoughput. Since they are 4GB
drives that gives an 8GB md device.

Now I want to use this md device for Informix Dynamic Server (yes,
the current iBCS can install and run IDS 7.20 for SCO...). IDS will
not let me have chunks greater than 2GB. Nor can I use the offset
for a chunk to take a <2GB slice out of a device greater than 2GB.
The only way to use a >2GB device for IDS is to put a filesystem
on it and use files as IDS chunks. This works but means that if
the system crashes I will need to fsck a large, mostly full filesystem
before I can bring IDS up again.

I really want to set up the md device then partition it. One
alternative would be to partition the disks then put the partitions
into a whole slew of md devices - but, IMHO, fragmenting one simple
setup step into many setups is not a good idea if it can be sensibly

I don't think allowing partitioning md devices would be _difficult_
but it would mean a change in the meaning of the md minor numbers.
Otherwise all the code is there - we just need the md devices to be
just a little more like disk devices.


|  Mike Jagdis                  |  Internet:  mailto:mike@roan.co.uk   |
|  Roan Technology Ltd.         |                                      |
|  54A Peach Street, Wokingham  |  Telephone:  +44 118 989 0403        |
|  RG40 1XG, ENGLAND            |  Fax:        +44 118 989 1195        |

- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/