Database performance question

DanGiles

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PREDATAR Control23

So, we all know how one should use separate disk for the database and storage pools, but what about the HBA ports. Logic seems to dictate (at least, MY logic) that one should not mix oltp and streaming data on the same fibre channels, but I can't find anywhere that actually states that. If I have 8 processes trying to steam data down a pipe, and each transaction must wait for a database update that has to go down the same set of pipes, won't they be stepping on each other's toes?

If I'm wrong, please let me know the fault in my logic. If I'm right, can someone point me to some reliable documentation so I an show the architects?

Thanks!
 
PREDATAR Control23

Hi,
i would think, that the streaming of large data require less IOPS that the database access.

But yes, theoretically I would say you are correct. When there is an io on the adapter the next io will have to wait for the first to get send out. So if you want extrem low latency you could separate the controllers. But low latency does not always mean high iops.

I did the opposit: Spreaded the database access over all available controllers. (And separated the access to tapes and file/diskpool-disks on different controllers). So I can use all the io-queues of all controllers simultaniously. And the io-queues on our storage-subsystem are also on a per port basis- Multipathing takes care of load-balancing. That way i hope to get the most IOPS out of our setup. Given that our storage backend is fast enough :)
 
PREDATAR Control23

So, as with most things techy, "6 of one, 1/2 dozen of the other".

I'm actually trying an experiment over the next 2 weeks. We just have 2 channels going to db and stg pool, round-robin load balanced, and the spindles were never separated. We are going to separate out the traffic through LUN masking at the source, so if there IS a performance improvement then I think I could say with confidence that separating the traffic is good.

I will post the results when available.
 
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