openstack swift slow LAN downloads

asked 2020-06-22 11:35:39 -0500

hi guys, hope you're all keeping well. i have a random slow download time on some files, which happens randomly across all my cluster. usually its pretty quick.

here's some of the stats (i'm testing the download of the same 64kb file every 10 mins in a cron job)...

usually i see good throughput (mbps) but when i see the very slow download, i see very low mpbs figures...

here's an example of 3 quick uploads during my script but one of the uploads is very slow and very low throughput mbps. the last download, the mbps drops off a cliff!

DC1 Swift Node 4 smallfileupload [auth 0.017s, headers 0.120s, total 0.120s, 0.610 MB/s]

DC1 Swift Node 5 smallfileupload [auth 0.018s, headers 0.933s, total 0.934s, 0.069 MB/s]

DC1 Swift Node 6 smallfileupload [auth 0.018s, headers 0.032s, total 0.032s, 4.547 MB/s]

DC 2 Swift Node 1 smallfileupload [auth 0.023s, headers 10.156s, total 10.162s, 0.006 MB/s]

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I don't think you can use a 64kb object for evaluating throughput. There are many factors that impact this test, for example the client might be swapped out. The short time to swap it in would still be much larger than the time to transfer the 64K.

TL;DR: Use a 64MB or 1GB object instead.

Bernd Bausch gravatar imageBernd Bausch ( 2020-06-22 21:51:18 -0500 )edit

To narrow this down, you could look at the Swift logs related to this upload request, and their time stamps.

Bernd Bausch gravatar imageBernd Bausch ( 2020-06-22 21:58:30 -0500 )edit