Re: direct (unbufferd) disk access

Khimenko Victor (khim@sch57.msk.ru)
Thu, 24 Jun 1999 20:01:49 +0400 (MSD)


In <19990624154447.L30370@mencheca.ch.genedata.com> Matthew Wilcox (Matthew.Wilcox@genedata.com) wrote:
> On Thu, Jun 24, 1999 at 11:35:56AM +0200, Christian Hammers wrote:
>> Hello List
>>
>> How can I get the kernel to read/write some data immediately to disk without
>> caching it in the kernel memory.
>>
>> I like to access one harddrive with two motherboards and like to have a shared
>> partition that will be writen to by one motherboard and read by an other
>> motherboard - but Linux seems to prevent that.
>>
>> I don't like to mount any partition (because of the filesystem check warnings)
>> and will instead write raw data with "dd".
>> Oh, and I don't like to flush ALL buffers, because this computer will be a
>> redunant web-server that strongly needs buffers (for this reasons AFAIK I
>> can't use flushb and sync).

> You want Stephen Tweedie's raw IO patches.

> ftp://ftp.uk.linux.org/pub/linux/sct/fs/raw-io

Just DO NOT ask about problems with your kernel when such patches are installed.
Linus has STRONG feeling AGAINST such patches (and AGAINST raw IO at all!) so if
you'll have problem with them do not bother him.

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