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January 29th, 2009 08:00
Prioritizing sync over async with SRDF?
If I have SRDF setup between two DMXs, some devices using sync mode and some using async, is it possible to prioritize the sync writes over async?
We have a group devoted to sync pairs so we can control each pair individually. If we were to convert to async we would either have to create up to 80 new RDF groups, each with between 1 and 4 devices, or lose the ability to manage these small device groups individually. So, we're not really concerned about data integrity so much as we are the ability to manage these many small sets of pairs separately.
What happened recently is that the async pairs generated quite a lot of traffic that flooded the link between the two sites, enough so that the response time on the sync devices was in the hundreds of milliseconds. What I would prefer is that async traffic will either throttle back to prevent slowing the sync replication or any sync IOs get to move to the front of the line so they get handled first.
We have a group devoted to sync pairs so we can control each pair individually. If we were to convert to async we would either have to create up to 80 new RDF groups, each with between 1 and 4 devices, or lose the ability to manage these small device groups individually. So, we're not really concerned about data integrity so much as we are the ability to manage these many small sets of pairs separately.
What happened recently is that the async pairs generated quite a lot of traffic that flooded the link between the two sites, enough so that the response time on the sync devices was in the hundreds of milliseconds. What I would prefer is that async traffic will either throttle back to prevent slowing the sync replication or any sync IOs get to move to the front of the line so they get handled first.
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bodnarg
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January 30th, 2009 05:00
If you are using GigE you could put all of your sync groups on one set of ports and the async on the other pair. You could then do one of the following:
1) Have EMC set bandwidth limits on the async ports (basically make them run at say 200Mb instead of 1000Mb.
2) Use network QoS settings based on source/target IP addresses.
Unfortunately don't think there is anything in the frame to let you distinguish between SRDF/S & SRDF/A priority wise so you I think doing something on the network/adapter side is all you may have available.
xe2sdc
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January 30th, 2009 02:00
Quincy561
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January 30th, 2009 03:00
xe2sdc
6 Operator
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2.8K Posts
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January 30th, 2009 04:00
Quincy561
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January 30th, 2009 05:00