no remap when not necessary

[weiyuan-jiang]

This PR address issue #52

[github-actions]

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[biljanaorescanin]

PR was tested for these cases:
If same atm res, same lev , diff ocean , same land => we will link upper restarts
If same atm res, same lev, same ocean, diff land => we will remap upper restarts
If same atm res, diff lev, same ocean, same land => we will remap upper restarts
Let me know if any other cases need to be tested.
@gmao-rreichle

[weiyuan-jiang]

PR was tested for these cases: If same atm res, same lev , diff ocean , same land => we will link upper restarts If same atm res, same lev, same ocean, diff land => we will remap upper restarts If same atm res, diff lev, same ocean, same land => we will remap upper restarts Let me know if any other cases need to be tested. @gmao-rreichle

"diff land" here is diff topo

[gmao-rreichle]

@sdrabenh, @biljanaorescanin, @weiyuan-jiang: It looks like this PR is meant to address a situation when upper air restart files do not need to be remapped and can just be linked. But why not apply the same checks to the land restarts? If the atm grid and bcs version (excl the topo files) are the same, land restarts don't need to be remapped. Any differences in the number of atm levels, the ocean grid, or the topo files shouldn't matter to the land restarts. I don't know how long it takes to remap high-res land restarts, but I imagine some savings could be realized by avoiding the unnecessary remapping of land restarts. Just a thought.

[weiyuan-jiang]

@sdrabenh, @biljanaorescanin, @weiyuan-jiang: It looks like this PR is meant to address a situation when upper air restart files do not need to be remapped and can just be linked. But why not apply the same checks to the land restarts? If the atm grid and bcs version (excl the topo files) are the same, land restarts don't need to be remapped. Any differences in the number of atm levels, the ocean grid, or the topo files shouldn't matter to the land restarts. I don't know how long it takes to remap high-res land restarts, but I imagine some savings could be realized by avoiding the unnecessary remapping of land restarts. Just a thought.

If everything is the same, then why do remap ?

[gmao-rreichle]

@weiyuan-jiang:

• If "topo" and "agrid" and "levels" are the same, we don't need to remap the upper air restarts. The "bcs version" could still be different (in something other than the "topo" files), which would mean that we have to remap the land restarts. I think that's what you implemented in this PR.
• If "agrid" and "bcs_version" are the same, we don't need to remap the land restarts. The "levels" could still be different, which would mean that we would have to remap the upper air restarts.

These are just two quick example situations. I didn't include the "ogrid" or the stretch factors in the example. The stretch factors should probably be considered in a bundle with "agrid". The full specs of the horizontal grid consist of the resolution ("agrid") and the stretch factors.

There are probably other combinations for which some (groups of) restarts may need to be remapped but not others.

My (admittedly vague) memory is that remapping land restarts can take a long time for high resolution bcs.

[weiyuan-jiang]

@weiyuan-jiang:

• If "topo" and "agrid" and "levels" are the same, we don't need to remap the upper air restarts. The "bcs version" could still be different (in something other than the "topo" files), which would mean that we have to remap the land restarts. I think that's what you implemented in this PR.
• If "agrid" and "bcs_version" are the same, we don't need to remap the land restarts. The "levels" could still be different, which would mean that we would have to remap the upper air restarts.

These are just two quick example situations. I didn't include the "ogrid" or the stretch factors in the example. The stretch factors should probably be considered in a bundle with "agrid". The full specs of the horizontal grid consist of the resolution ("agrid") and the stretch factors.

There are probably other combinations for which some (groups of) restarts may need to be remapped but not others.

My (admittedly vague) memory is that remapping land restarts can take a long time for high resolution bcs.

Indeed, there are some cases that land restarts don't need to remap. I will make some changes

[weiyuan-jiang]

The latest commit will not do the remapping if it is not necessary for all restarts

[weiyuan-jiang]

I changed link to copy. I prefer the output folder has all the restart files.

[biljanaorescanin]

Testing summary:
a) Automated tests passed
b) In red is what is diff to starting restart set

@gmao-rreichle

[gmao-rreichle]

Re-approving after 0-diff-trivial commit, which only updated USAGE text. No need to re-test.

[gmao-rreichle]

Approving again after one more 0-diff-trivial commit (making remap_restarts.py usage text consistent with corresponding Wiki page)