This message is from the T13 list server.

Hale, 

I have always thought that the reason to turn read look ahead off was to 
increase read cache performance. If there is an application that 
frequently 
re-reads recently read data then you want the largest possible read cache. 
By 
turning read look ahead off the drive can devote more cache to keeping 
previously
read data instead of using the buffer to store read ahead data. 

Best Regards,
Daniel J. Colegrove
Hitachi Global Storage Technologies

[EMAIL PROTECTED]
(702) 614-6119



Hale Landis <[EMAIL PROTECTED]> 
Sent by: [EMAIL PROTECTED]
06/29/2005 09:31 AM
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Hale Landis <[EMAIL PROTECTED]>


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Re: [t13] Read Look Ahead






This message is from the T13 list server.


Curtis Stevens wrote:
> This message is from the T13 list server.
> Hale
> I have to disagree with you.  I do not have any recollection of read
> ahead controlling read cache.  To the best of my knowledge, this 
disables
> look ahead in WD drives but has no effect on read cache.  Quite frankly 
I
> was shocked to hear that someone was actually interpreting the function 
as a
> cache disable.  No ATA rev has even hinted that this was a cache 
disable...

So both you and Mark are saying there is no documented way to disable 
read caching in an ATA drive? It is only possible to disable the "read 
look ahead" part of some more complex "read caching" algorithm?

Hale

-- 

++ Hale Landis ++ www.ata-atapi.com ++



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