[Swift-devel] Swift-issues (PBS+NFS Cluster)

[Ioan Raicu]

Hi Tim,

Tim Freeman wrote:
> Is that for speed or less moving parts?  I think EBS is the fastest option they
> have for disk space (faster than local disk), fyi.
>
>
>   
Can you elaborate more on how EBS, can be faster than local disk? I know 
nothing about EBS, but there are only 2 ways it can work. Since it is 
persistent, it likely lives on S3 (or something similar). When it is 
mounted, perhaps it still lives remotely, or perhaps it gets copied to a 
local disk, and runs locally. A locally running EBS, should be 
comparable in speed to a raw local disk, perhaps a bit slower for yet 
another layer of abstraction. If EBS lives remotely, perhaps in a 
completely idle EC2 cloud, a remote EBS might perform better than a 
local disk (assuming network communication is lighter-weight than 
SATA/PATA bus operations), but I can't imagine how this can hold true in 
a large scale and loaded cloud scenario, where shared infrastrucutre 
(network, S3, etc) can become congested under load.

I don't see how EBS can be faster than local disk. Can you elaborate 
more on this claim?

Thanks,
Ioan

-- 
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Ioan Raicu, Ph.D.
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Distributed Systems Laboratory
Computer Science Department
University of Chicago
1100 E. 58th Street, Ryerson Hall
Chicago, IL 60637
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Email: iraicu at cs.uchicago.edu
Web:   http://www.cs.uchicago.edu/~iraicu
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