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Enhancement: Fine tune distances between RSEs #837
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@KatyEllis @ericvaandering This issue is for what was discussed in our meeting today. Are there any more details that need to be added? |
I made a script to pull the RSE list in our CMS production node. I learned that each RSE is assigned a region (A, B, C, D), but I also found that not all RSEs are assigned a region. Would these RSEs need to have the region attribute applied? Are these regions defined somewhere? |
These regions were defined a long time ago based on some actual measurements. I guess the logic would have to be that things that don't have a region are treated worst off all for the region part of the calculation. But should be treated according to country if they have one, etc. Which sites don't have a region? Are any of them Tier2s? My suspicion is those sites got added and no one bothered to set the region since it's done by hand. |
@ericvaandering These are the sites that did not have a region assigned as an RSE attribute.
|
OK, from what I can see these mostly fall into Tier3 and un-used categories (Temp and Test). And Tape which surprises me but may make sense. Pulling off of tape should be last resort (but getting to tape should use the best link, so...) @nsmith- may have some insight here. I didn't go through exhaustively, but I only see Warsaw as a Tier2 with no region. As I recall the regions were roughly Western Europe, Eastern Europe, North America, and Other. Does that match what you see. |
This is all of the RSE region, tier and country:
From what I see, |
We (Fernando and I) used FTS logs to determine the rates and transfer efficiencies per link and then created a graph and used some tool (Gephi I think) to cluster the graph into 4 regions. I'm sure there is a presentation with details somewhere but I can't find it at the moment |
At least from what I see, the regional distances should be the following, from shortest to longest:
Would these have values between |
Don't forget B<->D and C<->D :) |
Based on a discussion with @KatyEllis: |
Set distances between: A (West Europe) and C (East Europe) regions to 11 C (East Europe) and D (Asia) regions to 12
Enhancement Description
Currently, two RSEs that do not share a region are given the slowest/longest distance value of 13, but that probably doesn't make sense.
Use Case
The fine tuning of distance could allow more optimal transfers.
Possible Solution
We may want to try a 4x4 matrix where the two European regions are declared better connected than Europe/US and where Europe and US are better connected than anything to Other.
The logic here could be modified:
CMSRucio/docker/rucio_client/scripts/cmslinks.py
Line 29 in fc5a7c4
Example Distances Comparison:
Same Site < Europe+Europe or US+US < Europe+US < Other
Related Issues
No response
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