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SubjectRe: Should raw I/O be added to the kernel?
Date
In article <linux.kernel.199901222150.VAA05394@dax.scot.redhat.com>,
Stephen C. Tweedie <sct@redhat.com> wrote:
>Hi,
>
>On Thu, 21 Jan 1999 21:39:26 +0100 (MET), Gerard Roudier
><groudier@club-internet.fr> said:
>
>> Providing integrity using only a synchronous IO semantic is so costly for
>> performances that I donnot even want to think for a second to such an
>> approach.
>
>Interesting to hear you say this, since that is _precisely_ what you get
>if you are running a large DB like Oracle or Informix on raw devices.
>All raw devices are _necessarily_ synchronous, and yet these devices are
>suggested as a means of improving performance.

Hopefully nobody is still saying this. In the old days, when
processors were slow and DMA didn't exist, copies were bad,
but I don't think that any systems built in the last decade
suffer from this disadvantage.

People were still saying this when I worked for the idiots at Sybase
about a decade ago, and they (we) kept putting our feet in it when
our victims would try that out, only to realize that scribbling on
a filesystem was considerablty faster (if somewhat less reliable)
than scribbling on raw partitions.

____
david parsons \bi/ Fast or Safe, take yer choice.
\/

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