8MB picture takes 9 sec to download. How can I speed this up?

The process of downloading a file can decomposed into:

• reading the file from the remote system
• transferring the file over the from the remote system's network to the internet and finally to your local network
• writing the file to the local system

To get a baseline for how long it takes to download files of that size from a system local to the Atlanta data center, I created a bucket and Linode in the us-southeast-1 region. I then generated a files of the same size as you describe:

dd if=/dev/random of=5.1MB_file bs=5100000 count=1 iflag=dsync,fullblock
dd if=/dev/random of=8.29MB_file bs=8920000 count=1 iflag=dsync,fullblock

I used s3cmd to upload the files:

Atlanta Upload

The 5.1MB_file took 0.447s and the 8.29MB_file took 2.098s to upload in total, but both took under 0.5s for the transfer to occur.

root@localhost:~# time s3cmd put 5.1MB_file s3://bucket/5.1MB_file
upload: '5.1MB_file' -> 's3://bucket/5.1MB_file'  [1 of 1]
 5100000 of 5100000   100% in    0s    22.47 MB/s  done

real    0m0.447s
user    0m0.146s
sys    0m0.030s
root@localhost:~# time s3cmd put 8.29MB_file s3://bucket/8.29MB_file
upload: '8.29MB_file' -> 's3://bucket/8.29MB_file'  [1 of 1]
 8290000 of 8290000   100% in    0s    26.31 MB/s  done

real    0m2.098s
user    0m0.153s
sys    0m0.034s

Atlanta Download

The 5.1MB_file took 0.399s and the 8.29MB_file took 3.198s to download from a Linode in Atlanta, but both took under 0.5s for the transfer to occur. The rest is just connection overhead.

root@localhost:~# time s3cmd get s3://bucket/8.29MB_file
download: 's3://bucket/8.29MB_file' -> './8.29MB_file'  [1 of 1]
 8920000 of 8920000   100% in    0s    51.53 MB/s  done

real    0m3.198s
user    0m0.159s
sys    0m0.034s
root@localhost:~# time s3cmd get s3://bucket/5.1MB_file
download: 's3://bucket/5.1MB_file' -> './5.1MB_file'  [1 of 1]
 5100000 of 5100000   100% in    0s    25.09 MB/s  done

real    0m0.399s
user    0m0.133s
sys    0m0.045s

Fremont Download

The 5.1MB_file took 2.747s and the 8.29MB_file took 7.639s to download from a Linode in Fremont, the actual transfers took 2s and 3s respectively however.

root@localhost:~# time s3cmd get s3://bucket/8.29MB_file
download: 's3://bucket/8.29MB_file' -> './8.19MB_file'  [1 of 1]
 8290000 of 8290000   100% in    3s     2.17 MB/s  done

real    0m7.639s
user    0m0.225s
sys     0m0.061s
root@localhost:~# time s3cmd get s3://bucket/5.1MB_file
download: 's3://bucket/5.1MB_file' -> './5.1MB_file'  [1 of 1]
 5100000 of 5100000   100% in    2s     2.14 MB/s  done

real    0m2.747s
user    0m0.181s
sys     0m0.074s

Takeaways

It looks like connection overhead is the biggest part of the time you are seeing. You may wish to use a tool such as CyberDuck to process your downloads in one session or in parallel.

• https://www.linode.com/docs/products/storage/object-storage/guides/cyberduck/

Some other possible contributing factors

• Variability in Object Storage performance due to demand
• Internet Transit Problems: https://www.linode.com/docs/guides/diagnosing-network-issues-with-mtr/
• Downloading from the Cloud Manager can be much slower due to the possibility that it might need to relay the data from object storage for you
• IO overhead on your local system
• Network overhead on your local network

I hope this helps!