Linux-kernel mailing list archive 1998-48,: Re: Wanted: partitionable md devices

# Re: Wanted: partitionable md devices

Terry L Ridder (terrylr@tbcnet.com)
Thu, 03 Dec 1998 14:52:26 -0600

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

Sounds like something you will be busy on over the holidays.

>
> 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.

Why not use the Informix Dynamic Server native to Linux?

>
> 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
> avoided.

Sounds more like you want to create a logical volume and
partion the logical volume. This sounds more like a volume
manager than md.

>
> 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.
>

How would you ensure backward compatibility?

> Mike
>

    --
    Terry L. Ridder
    Blue Danube Software (Blaue Donau Software)
    "We do not write software, we compose it."

     entertaining angels
     by the light of my computer screen
     24-7 you wait for me
     entertaining angels
     while the night becomes history
     host of heaven, sing over me
     ==Entertaining Angels==Newsboys

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