[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[LDM #GBK-975146]: slight differences between files

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: [LDM #GBK-975146]: slight differences between files
  • Date: Wed, 01 Feb 2017 16:14:01 -0700
Erik,

I didn't realize that the two LDM were requesting from each other as well as 
from
the upstream LDM-s -- in which case the timing of the comparison is irrelevant.

Basically, if there's more than a single path from the source of the data to the
final LDM, then the sequence of data-products as seen by the final LDM can 
differ
from the sequence sent by the source LDM due to some LDM's queue being too 
small.
Here's the sequence that could lead to that:

    1. Product 1 received from LDM A
    2. Product 2 received from LDM A
    3. Product 1 deleted from queue to make room for more products
    4. Product 1 received from LDM B
    5. Product 2 rejected from LDM B because it's already in the queue

The LDM will now relay/process products in the order 1, 2, 1.

The size of an LDM queue -- both the amount of data size and the number of
slots -- needs to be large enough that the minimum residence time of a product
in the queue is greater than the maximum latency parameter in the LDM registry.
And this must be true for every LDM between you and the source.

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: GBK-975146
Department: Support LDM
Priority: Normal
Status: Closed
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.