Mirror server?

Hi all,

Whilst I was patching "wd" yesterday (to support a second IDE controller
card) I had an idea about getting disk mirroring in software (a soft RAID
idea). I know that there are some relatively cheap ways of doing this in
hardware, but I think a soft solution would offer some possible advantages
since it should be possible to mirror to just about any device in software
(maybe even a network). Here are a few of my original ideas (I've no idea
if they're at all practical- I think they are though):

        Device 1 Device 2

        IDE HDD IDE HDD
        SCSI HDD SCSI HDD
        IDE HDD SCSI HDD
        any HDD network drive

I got to thinking that maybe it would be possible to guard against some data
loss by mirroring data on the same physical device as well (two copies,
maybe one in each of two disk partitions).

Finally I thought it should be possible to "stripe" data across a number of
devices - ie we provide a mechanism to allow multiple partitions/devices to
be joined together via a server to provide one logically larger device.

There's no reason (that I can think of) why such a server couldn't handle
maybe 3 or 4 devices rather than just 2.

The implementation I was thinking of would connect to all of the
devices/partitions/files that we'd like to store data on and provide a
mechanism whereby these would be seen as one logical device. The server
would advertise a port that to all intents and purposes would appear to be
any other block device.

I know there'd be issues with handling fails (I haven't really looked around
to see if there are any good papers on this), but I'd think that VSTa must
be a superb environment to tinker with this sort of code.

I haven't got time just at the moment to start coding such a server, but
it's something that I think would be quite interesting to develop.

Any comments?

                Regards,
                Dave
Received on Thu May 12 12:38:48 1994