Does size matter?

[tyler811]

I have a choice of how to big to make the stripe size from 4 to 128 KB big. How big should it be?



Moved to Memory and Storage
Anandtech Moderator
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[jterrell]

Depends on usage.

No one size fits all there.
I'd say gaming environments where you have large numbers of small reads and writes are probably better off with larger stripe sizes (but only to a point); applications where smaller numbers of larger files need to be read quickly will likely prefer smaller stripes. Obviously, if you need to balance these requirements, choose something in the middle. Best info will be achieved by testing both.

The bigger issue is the number of disks. More disks generally mean better performance up to the sweet spot of say an 8 disk stripe.

 

[imported_wired247]

Generally the largest stripe size gives you best performance.

If your HD is doing many many reads of small files, a smaller stripe size would be warranted. If you are totally unsure, use 64kB. But I would (and I do) use 128KB unless you know a specific reason you should not be doing so.

Originally posted by: jterrell
Depends on usage.

No one size fits all there.
I'd say gaming environments where you have large numbers of small reads and writes are probably better off with larger stripe sizes (but only to a point); applications where smaller numbers of larger files need to be read quickly will likely prefer smaller stripes. Obviously, if you need to balance these requirements, choose something in the middle. Best info will be achieved by testing both.

The bigger issue is the number of disks. More disks generally mean better performance up to the sweet spot of say an 8 disk stripe.

the bold and underlined part is wrong. Large stripe sizes favor larger files.

here's a decent article on raid stripe size
http://www.tomshardware.com/20...ling_charts/page4.html

with some nice benchmarks
http://www.tomshardware.com/20...ling_charts/page9.html



so cliff's notes... set stripe size to maximum unless you know for sure you would benefit from smaller than maximum.

 

[Madwand1]

There is no single generally-valid answer, which is why there's an option to change the stripe size in most (though not all) implementations.

So the answer will generally be dependent on the RAID implementation, RAID mode, number of drives, and applications.

Without all this information and specific benchmarks, debating various stripe sizes is fairly pointless.

 

[cbuchach]

I've looked at this too and all kinds of different benchmarks and theories. It does matter what controller you are using and the hard disks to some extent--different benchmarks will show different things.

On my setup I am using the Intel ICH8R with RAID0 and went with what I thought was a good compromise of 64KB stripes. In any event, going any of the common stripe sizes isn't going to noticeably improve or detract from your performance.

 

[jterrell]

I hear what they are saying but you have to be careful with that line of thought.

I have configured a ton of SANs and various stripes and especially with DB performance the larger files will fill a cache so you want smaller writes so as to avoid write waits.

Write waits is the leading cause of bottlenecks on systems.

 

[LeadMagnet]

1920kb per drive strip (element)