Messages in this thread | | | Date | Tue, 6 Jan 1998 06:13:50 +0100 | From | ralf@uni-kobl ... | Subject | Re: lack of raw disk devices |
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On Sun, Jan 04, 1998 at 11:48:50AM -0500, linux kernel account wrote:
> On Sun, 4 Jan 1998, Harald Milz wrote: > > > Marty Leisner (leisner@sdsp.mc.xerox.com) wrote: > > > I understand linux doesn't have raw devices because > > > we don't need it. > > > > We actually do. A couple of database product make use of raw devices if > > they exist, e.g. Oracle. > > They are just looking for excuses.. They could use whats already there.. > They just would have to deal with the fact that the OS is going to cache > things in ways they dont like..
In a way that makes error recovery impossible for the database.
> They want to have complete input/output cach control.. Yes, that would be > important if Linux was their prime target..
Customer calls Oracle (Sybase etc.): ``Your friggin database engine fucked my entire 1TB database. I hope your competition does better ...''
Cite manual of xy-db ... ``Linux: We're sorry, if your box should crash, your database might be fried'' ...
Wouldn't that be good promotion?
> But they could just say 'the > Linux version is beta/not as good and stable because of it' and when they > decide that Linux was a platform they really like: They could make a > friggen kernel module to provide a raw interface.
That would be a horrible hack that'd break once a new kernelpatch is released. And that's still the least problem.
This is not a vote for a blind implementation of raw devices. Raw devices have their problems by design, mainly because of a lack of communication between the buffercache and the userspace cache in the db engine.
Ralf
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