Re: PATCH: Raw device IO for 2.1.131

Martin Tessun (martin.tessun@class.de)
Wed, 16 Dec 1998 08:39:01 +0100

> Linus, the point is that there _are_ applications out there which do use raw
> devices on other Unix variants, like Oracle, Sybase, etc. If I go to a
> customer and want to sell a Linux solution, and Oracle told him "well we do
> support Linux but it's suboptimal compared to HP, Sun because we can't use
> raw devices" who is going to tell the customer he is in good hands? Is it
> you? Or are you going to tell the customer what is good for him? Just like
> IBM did in the past (and sometimes, still today?) This is arrogant.

Perhaps this is not the right topic, but I want to say a few words to
Oracle:

Oracle uses raw-devices, because they thought it was the fastest
solution. In the meantime they have support for NetApp-Filers. So Oracle
goes through the Net (may be private for being faster) and then runs
into the Cache of the NetApp-Filer. So Oracle has no overhead for
Filemanagement, and can be faster so, and the Net-App-Filer is optimized
for Disk-IO and is thus faster.

The Bottleneck in this configuration is the net. But still Oracle
support this solution and say that it is indeed faster than the
Raw-Device solution if you have a fast net.

So if the File-Handling of Linux is better than in other Unixes why not
use the "normal" Devices. Even this is supported by Oracle and often set
up so, because increasing Database-Size is much easier than with
Raw-Devices.

And "normally" other Unixes use their Raw-Devices for fschk-ing their
partitions. Even that's the point why there are Raw-Devices at all.

Martin

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