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Re: MySQL + NAS(NFS) - Possible solution?
Posted by: Ingo Strüwing
Date: September 26, 2005 07:08AM

You write:
> I'm wondering if the overhead will really matter, through the dedicated link and their
> proprietary fs (WAFL), in general the NetApps is at least as fast as local disk, including
> NFS overhead. I think (not positive) that I've also read in another of their documents that
> they lie to the client OS and mark the write as complete as soon as it's committed to their
> NVRAM cache in certain circumstances (had to do with NFS mount options). Through the
> GigE link this should be insanely quick, I'd think.

I agree, but need to clear a misunderstanding. MyISAM does not use O_SYNC nor O_DIRECT. This means that a write(2) will copy the data into one or more block(s) of the file system buffer and return immediately. The application can continue without wait. The file system flush process will flush the modified block(s) later at its own discretion. MyISAM has no control over this flushing.

Now the question is: Is the network traffic as fast as a local RAM-to-RAM copy?

But anyway make a try with O_DIRECT and tell me. ;)

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Re: MySQL + NAS(NFS) - Possible solution?
September 26, 2005 07:08AM

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