> On Fri, 18 Oct 1996, David Monro wrote:
> > Something I've been wondering about for a bit - why doesn't linux have the
> > equivalent of the "raw" disk devices present on most other unixen I can think
> > of (OSF, Solaris, SunOS, *BSD)? (For people who haven't seen them, the device
> > name is traditionally the normal block device with a 'r' prefixed, and it is
> > a char device rather than a block one). I was talking to a unix kernel guru I
> > know about what they are used for, and there seem to be two things:
> The main reason there are no raw devices is that I personally think that
> raw devices are a stupid idea.
> Sure, there are old-fashioned databases that think they can do a better job
> of it than the kernel does. They are usually wrong, I suspect. They are using
> raw devices more for historical reasons than anything else, and they could
> just as well use a filesystem.
Well, I definitely don't like raw devices for databases at all. First,
todays kernels do a real good jobs with block devices compared to raw
devices. I guess the difference was much greater in the early (earlier=
days of (unix-)kernels.
And I also can imagine that going to the storage device (whatever that
will be) through the kernel will give me more confidence re future
developments of storage devices that I can connect to my computer
without having to wait for the n+1'th upgrade of that db kernel that
knows how to cope with that new device.
I would prefer having a db that goes to its files via some ufs-stub than
trying to reinvent the wheel for a job the kernel does already.
> There _are_ databases that successfully use filesystems for storage, and they
> often have obvious advantages (like having BLOBs as separate files so that
> you can actually access those satellite pictures without going through the
> database etc).
I agree wholeheartedly
Klaus Lichtenwalder, Dipl. Inform., PGP Key: email to key@Four11.com
Lichtenwalder@ACM.org, http://www.wp.com/Klaus, fax: +49-89-9829275
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