[Landsat-pds] Upcoming updates to Landsat on AWS data

Wed Sep 30 12:50:04 PDT 2015

Thanks for the update, Amit. Is it possible that this new limit could cause us to fall behind in acquiring all new scenes as they’re produced each day?

On Sep 30, 2015, at 12:00 PM, Amit Kapadia <amit at planet.com<mailto:amit at planet.com>> wrote:

Hey Jed,

Thanks for reaching out to them. Looks like we have another rate-limiting error to handle:

usgs.USGSError: RATE_LIMIT: Rate limit exceeded - cannot support simultaneous requests.

According to the changelog of the USGS inventory service:

August 2015

 * Implemented single-stream rate limiting
 * Added FGDC Metadata URL to search and metadata responses
 * API Key is now required for all requests

Despite the change being made in August, we're only now starting to see this error. Previously, we were allowed 2 simultaneous downloads per machine. This has been cut in half. To keep up with the flow of Landsat scenes, we need simultaneous requests. This error is cropping up periodically in our re-ingestion of the ~53,000 scenes, as well as our daily ingestion.

Enforcing single-stream per machine is a terrible waste of computing resources.

Also note, the need of an API key for all requests. Previously, anyone was able to programmatically access metadata. This is no longer possible.

Any help would be appreciated.

Cheers,
Amit

On Mon, Sep 28, 2015 at 3:38 PM, Sundwall, Jed <jed at amazon.com<mailto:jed at amazon.com>> wrote:
I’ve reached out to USGS to ask if we can increase the limit.

Thanks for the update, Amit!

On Sep 28, 2015, at 12:16 PM, Amit Kapadia <amit at planet.com<mailto:amit at planet.com>> wrote:

Another update on the reingestion of these ~53,000 scenes. We've moving along faster than the initial few weeks. Currently we have ~28,500 scenes left to reprocess. This is taking a bit of time, mostly because USGS rate limits the number of scenes that can be simultaneously downloaded.

Jed - we often hit an error of this sort:

DOWNLOAD_RATE_LIMIT: User currently has more than 10 downloads that have not been attempted in the past 10 minutes.

If there's a way we can work with USGS on getting this type of rate-limiting lifted, I'll be able to spin up additional workers, breaking through this 10 scene limit. No big deal if that's not possible.

Cheers,
Amit

On Tue, Sep 15, 2015 at 10:58 AM, Amit Kapadia <amit at planet.com<mailto:amit at planet.com>> wrote:
We're ingesting about 1.35 scenes per minute (~2000 scenes per day). With 44,200 scenes remaining, this work should be complete in 22 - 23 days.

The additional worker has kicked up the rate. I'm learning more about the rate-limiting that USGS imposes, and it seems that a single machine is limited to 2 concurrent downloads (we already knew this). However, we have 3 machines running, so the rate-limiting appears to be a combination between IP address and EROS account.

Cheers,
Amit

On Mon, Sep 14, 2015 at 3:58 PM, Sundwall, Jed <jed at amazon.com<mailto:jed at amazon.com>> wrote:
Thanks for the update, Amit. Could you please let us know if you see that the extra workers have upped our rate? Also, if you can estimate when this would be done?

Thank you very much for your work on this!

Jed.

On Sep 14, 2015, at 2:16 PM, Amit Kapadia <amit at planet.com<mailto:amit at planet.com>> wrote:

Hi all - an update to the ingestion of these reprocessed Landsat scenes. Using the additional bandwidth that Jed locked down, we've ingested ~8,000 of the 52,877 scenes. This has been moving a little slow, so I've bumped up the number of workers.

In the past we've been restricted to 2 concurrent downloads from USGS servers, but it now seems that we're able to get 4 concurrent downloads. I'll try our luck with one more worker (2 more downloads) to see if we're allowed this luxury.

Ingestion of new Landsat scenes continues as normal.

Cheers,
Amit

On Wed, Aug 26, 2015 at 12:08 PM, Sundwall, Jed <jed at amazon.com<mailto:jed at amazon.com>> wrote:
Quick update:

We have been granted additional bandwidth to acquire Landsat data from EROS and will use it to reacquire 53,206 scenes that have been reprocessed with updated TIRS data as described at http://landsat.usgs.gov/calibration_notices.php

We will also use this opportunity to check for any scenes that we may have failed to acquire throughout 2015. Another user of the data recently pointed out that "USGS states that there are 149307 scenes so far in 2015, but AWS claims to host only 145746 of them. As a percentage, that is 97.6% - IOW 2.4% are missing.” These scenes may be missing from the bucket or they may merely be missing from the scene_list.gz file.

I’ll update the list once the reacquisition is complete.

Thanks,

Jed Sundwall – Open Data – Amazon Web Services

cell: 801-949-1482<tel:801-949-1482>
office: 206-435-3104<tel:206-435-3104>

https://aws.amazon.com/opendata/

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