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Info

Following the previous paragraph,  the natural way to group requests would be:
all parameters, all levels, all members, all time-steps for 1 date.

(warning) Note the following:

  1. 'all' means 'all' that the user wants. It doesn't have to be all parameters.
  2. If a user is interested only on z500,  he may request more dates in one go, since the overall request will not be so big.

 What is the best approach to loop over several

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dates  for a CMA request?

Info
titleThe main idea in brief:
for date in date-list
     your-request (includes the levels, parameters, steps etc)

An example to request Control forecast, pressure levels from 2010-03-01 to 2010-03-31

Info
titleThe main idea in brief:
for each year from 2010-03-01 to 2010-03-31
    your-request

What is the best approach to get all days for several years and months ?

Info
titleThe main idea in brief:
for year in years (firstly iterate over years)
    for month in months (secondly iterate over months of the year)
        for days in days (thirdly iterate over the days of the month)
             your-request (includes the levels, parameters, steps etc)

An example to request Control forecast, sfc, for years 2010-2014 for 2 months (eg April and June)

Info
titleThe main idea in brief:
for each year from 2010 to 2014
    for months April, June
            your-request

What is the best approach to get all days for several years and months  and for several hincasts ?

Info
titleThe main idea in brief:
for year in years (firstly iterate over years)
    for month in months (secondly iterate over months of the year)
        for days in days (thirdly iterate over the days of the month)
             for hindcast in hindcasts
             hindcast-list
          your-request (includes the levels, parameters, steps etc)

An example to request Control forecast, sfc, for years 2010-2014 for 2 months for all hincasts (eg April and June)

Info
titleThe main idea in brief:
for each year from 2010 to 2014
    for months April, June
            your-request



An example to request Control forecast, pressure levels, for years 2010-2014 for 2 months (eg April and June)

Info
titleThe main idea in brief:
for each year from 2010 to 2014
    for months April, June
        for each hindcast date
            your-request


 



old below:

---------------

Info
titleThe objective:


cf and pf are stored separately. 

For pf is not efficient to do:
        HDATE = 20040101/20040106/20040111/20040116/20040121/20040126/20040201/20040206/20040211/20040216/20040221/20040226/20040301/20040306/20040311/20040316/20040321/20040326/20040401/20040406/20040411/20040416/20040421/20040426/20040501/20040506/20040511/20040516/20040521/20040526/20040601/20040606/20040611/20040616/20040621/20040626/20040701/20040706/20040711/20040716/20040721/20040726/20040801/20040806/20040811/20040816/20040821/20040826/20040901/20040906/20040911/20040916/20040921/20040926/20041001/20041006/20041011/20041016/20041021/20041026/20041101/20041106/20041111/20041116/20041121/20041126/20041201/20041206/20041211/20041216/20041221/20041226,
        NUMBER = 1,

but it is more efficient to group all members in one go for fewer dates:
        HDATE = 20040101/20040106/20040111/20040116/20040121/20040126,
        NUMBER = 1/to/50
This implies less positioning and more contiguous reads.

We could look at increasing the 10GB limit. We have more hardware and are in a better position to handle bigger chunks.


For the 3 allowed streams, I would extract different type/levtype in different streams. For instance:
a) 1 stream: pf/sfc
b) 1 stream: pf/pl
c) 1 stream: cf/sfc and when it finishes,cf/pl
and I would put 2 requests for each stream above. Once a request finishes and starts the downloading, the next request will kick in, and it will find in many cases that the tape volume is still in the tape drive, which will save in avg 2 minutes for a tape mount.




 


 

 



An example to request Control forecast, pressure levels, for years 2010-2014 for 2 months (eg April and June)

Info
titleThe main idea in brief:
for each year from 2010 to 2014
    for months April, June
        for each hindcast date
            your-request


 



old below:

---------------
 

Info
titleThe objective:


cf and pf are stored separately. 

For pf is not efficient to do:
        HDATE = 20040101/20040106/20040111/20040116/20040121/20040126/20040201/20040206/20040211/20040216/20040221/20040226/20040301/20040306/20040311/20040316/20040321/20040326/20040401/20040406/20040411/20040416/20040421/20040426/20040501/20040506/20040511/20040516/20040521/20040526/20040601/20040606/20040611/20040616/20040621/20040626/20040701/20040706/20040711/20040716/20040721/20040726/20040801/20040806/20040811/20040816/20040821/20040826/20040901/20040906/20040911/20040916/20040921/20040926/20041001/20041006/20041011/20041016/20041021/20041026/20041101/20041106/20041111/20041116/20041121/20041126/20041201/20041206/20041211/20041216/20041221/20041226,
        NUMBER = 1,

but it is more efficient to group all members in one go for fewer dates:
        HDATE = 20040101/20040106/20040111/20040116/20040121/20040126,
        NUMBER = 1/to/50
This implies less positioning and more contiguous reads.

We could look at increasing the 10GB limit. We have more hardware and are in a better position to handle bigger chunks.


For the 3 allowed streams, I would extract different type/levtype in different streams. For instance:
a) 1 stream: pf/sfc
b) 1 stream: pf/pl
c) 1 stream: cf/sfc and when it finishes,cf/pl
and I would put 2 requests for each stream above. Once a request finishes and starts the downloading, the next request will kick in, and it will find in many cases that the tape volume is still in the tape drive, which will save in avg 2 minutes for a tape mount.


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