[ale] Build-yer-own NAS server

[J. D. Pearson]

>> NCQ allows multiple outstanding write requests to live on the drive,
>> but still allows write-barriers to be supported as needed for
>> journaled FS.  I don't understand the details, but without NCQ
>> journelled FSes generally recommend turning off write-cache in the
>> drive so you can only have one write request on the drive at a time.
>
>> Back on topic:
>> There has been some discussion on the sata kernel list about NCQ.
>> They have it working in the new big rewrite (NCQ may not get in until
>> 2.6.19), but benchmarking is showing it causes a small performance
>> drop for many (most?) workloads!!!.
>
>> Per one of the developers, NCQ makes a big difference if the OS does a
>> poor job of using a elevator i/o scheduler like a "certain OS", but
>> Linux 2.6 has a very good elevator i/o scheduler so you actually see a
>> drop in performance when NCQ is enabled for general workloads.
>
>> So, I don't think it is a feature I will use.
>  
>

    Wow that is interesting Greg. Definitely something to think about. 
Thanks for
pointing it out to me. Are the non-SATAII drives still widely available?

Best regards,

J. D.