Re: RES: Initial database loading and IDE x SCSI

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От Mark Kirkwood
Тема Re: RES: Initial database loading and IDE x SCSI
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Msg-id 4480D427.50207@paradise.net.nz
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Ответ на Re: RES: Initial database loading and IDE x SCSI  (Mark Lewis <mark.lewis@mir3.com>)
Ответы Re: RES: Initial database loading and IDE x SCSI  (Bruce Momjian <pgman@candle.pha.pa.us>)
Список pgsql-performance
Mark Lewis wrote:

>
> The naive approach works on IDE drives because they don't (usually)
> honor the request to write the data immediately, so it can fill its
> write cache up with several megabytes of data and write it out to the
> disk at its leisure.
>

FWIW - If you are using MacOS X or Windows, then later SATA (in
particular, not sure about older IDE) will honor the request to write
immediately, even if the disk write cache is enabled.

I believe that Linux 2.6+ and SATA II will also behave this way (I'm
thinking that write barrier support *is* in 2.6 now - however you would
be wise to follow up on the Linux kernel list if you want to be sure!)

In these cases data integrity becomes similar to SCSI - however, unless
you buy SATA specifically designed for a server type workload (e.g WD
Raptor), then ATA/SATA tend to fail more quickly if used in this way
(e.g. 24/7, hot/dusty environment etc).

Cheers

Mark

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