Messages in this thread | | | From | Ronald Cole <> | Date | Sun, 20 Dec 1998 22:56:48 -0800 (PST) | Subject | Re: Should raw I/O be added to the kernel? |
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Linus Torvalds <torvalds@transmeta.com> writes: >The only argument for raw disk IO is the caching policy issue
Exactly right. Without raw disk IO, you couldn't guarantee a database to always be in a consistent state on the disk (i.e. it isn't very desirable to have a committed transaction in a cache when the pc loses power). It makes it impossible to recover the database. And what good is having a transaction oriented database on Linux in a production environment if you can't be guaranteed to recover it after a crash?
From my days at Unify a decade ago, you had to use raw disk IO because fsync() wasn't guaranteed to have flushed the cache completely to the disk before it returned. Of course, I'll be the first to admit that I haven't checked out the kernel source to see if this is true for Linux. But, I'm sure that someone will so that the database part of this thread can be put to rest.
-- Forte International, P.O. Box 1412, Ridgecrest, CA 93556-1412 Ronald Cole <ronald@forte-intl.com> Phone: (760) 499-9142 President, CEO Fax: (760) 499-9152 My PGP fingerprint: 15 6E C7 91 5F AF 17 C4 24 93 CB 6B EB 38 B5 E5
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