[Linux-cluster] I/O scheduler and performance

RR ranjtech at gmail.com
Wed Jul 5 04:30:24 UTC 2006

Hi Wendy,

thanks for the prompt response. I see what you're saying. Just a few
things to clarify. The databases I have are clustered active-passive,
so only one machine accesses the store at any given time with a
persistent connection to the SAN.
Also, yes, I would think that for this particular application the IO
pattern might be very close to parallel in nature as essentially all
cluster nodes will run the same application accessing the same store
but may rarely access the same folder at the same time and if they do,
it would be independantly of each other. I guess the community
involved with the development of this application isn't too familiar
with clustered filesystems and they may be considering database
storage over shared filesystems such as NFS or something but they seem
to suggest that database storage offers better scalability and less
administrative overhead. I do care about the administrative overhead
but performance is a bigger criteria. The other thing I should point
out is that whereas the clustered databases use HBAs to access the SAN
the linux cluster nodes running the application will access the SAN
using GigE NICs. The performance and CPU overhead of not being able to
use HBAs might be an added factor, do you think?

I'm totally neutral about either solution, I just want the best
performance with whatever I go with, so I wonder if a database person
on the list can give their view as well?

Best Regards,

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