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 Post subject: Which disk access is faster?faster
PostPosted: May 16th, 2011, 6:45 
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Joined: May 16th, 2011, 6:07
Posts: 1
Location: Wales
Hi,

Which of the following two scenarios is faster, given that all other factors would be the same:

One disk accessed twiced, once at each edge (inner and outer) OR

Two disks simultaneously accessed once each.

The reason for this query is I want to know if it will speed-up my PC if the OS is on one drive and the applications are on another?

Regards,

Fretful.


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 Post subject: Re: Which disk access is faster?faster
PostPosted: May 16th, 2011, 19:08 
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Joined: May 6th, 2008, 22:53
Posts: 2138
Location: England
fretful wrote:
Which of the following two scenarios is faster, given that all other factors would be the same:

There are other factors which you haven't mentioned (doesn't matter if they're the same or not, between the 2 configs) which will affect whether or not you actually measure much performance difference, but...

fretful wrote:
One disk accessed twiced, once at each edge (inner and outer) OR

Two disks simultaneously accessed once each.

From all my experience on performance investigations, I have never seen two I/Os to one disk (especially with a seek between them), be faster than one I/O to each of two disks (since these could be done in parallel) - i.e. the latter is typically faster. However, there are other factors about the exact usage, which might make the performance difference minimal.

fretful wrote:
The reason for this query is I want to know if it will speed-up my PC if the OS is on one drive and the applications are on another?

Although using 2 disks, as you describe above, has the potential for some PC operations to be faster, I could construct some tests which would show minimal useful improvement and other tests which would show significant improvement. In other words - YMMV. :)

Since this forum isn't dedicated to PC performance & configuration, then this may not be the best place for you to ask your question. However I/O performance (on *nix-based systems) is something I've worked on for many years, so with the limited info available, I've given you some general info to answer your question. :)


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