[ale] Build-yer-own NAS server

[Greg Freemyer]

On 6/8/06, J. D. Pearson <jpearson at turbocorp.com> wrote:
>
> >> 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?
>

Okay, my turn for ignorance.

Is NCQ only a feature on SATAII (SATA 300?) drives?  And yes there are
still plenty of PATA and SATA 150 drives on the market.

The new 750GB drives that Seagate is selling are available in PATA,
SATA 150, and SATA 300.  I don't know which if any have the NCQ
feature.

Greg
-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century