[3dem] Falcon II uses only half of the 1Gb/s bandwidth.

[Matthias Wolf]

Hi Gene,


Don't bother with the inadequate FEI microscope PC and its gigabit network.


For proper performance, you have 2 options:


  1.  get FEI's storage server and frame saving hardware (CMTS) with dedicated 10Gbit/s upload. It'll cost you $$$. Needs Win7 on the scope PC.

  2.  set up Greg McMullans brilliant Falcon frame capture, which uses a beam splitter (fiber optical tap) to duplicate the raw camera signal and capture it on a dedicated linux PC with fast SSD. Total investment ~3k US$. This works on older Win XP systems, but Greg has also written code for Win7 (FEI changes something in the Falcon data protocol upon upgrade to Win7). You may want to look up Chen Xu's "falcon hacking" page at Brandeis on Internet Waybackmachine. That way, the FEI system is completely bypassed and your movie frames will be happily saved on the capture PC before you even get an image in TIA. I have done this with good success for several years until option 1 was installed in the course of a Win7+Falcon3 upgrade. You must obtain specific Solarflare NICs for Greg's code to work and should follow his instructions to the letter (but best don't bother him and go with option 1)!


Image size is 16 Mpixel * 14bit/pixel. At 18 fps, the data rate is ~4 Gb/s.

Decent hardware can deal with this. The camera can go to 32 fps or even higher, but then everything on the linux O/S must be tuned or you drop frames.


Without frame capture, you won't get decent performance - both number of frames and frame rate will be severely limited and not up to current standards of cryo-EM movie data collection.


As Steve wrote, your gigabit switch is unlikely to throttle bandwidth.

But the raw camera data is sent in jumbo packets. Maybe your switch is using standard MTU of 1500?

You could try changing this to use jumbo packets of 9014 bytes with telnet and the CLI.


   Matthias


________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Eugene Pichkur <eugene.pichkur at gmail.com>
Sent: Tuesday, October 16, 2018 10:15:00 PM
To: 3dem at ncmir.ucsd.edu
Subject: [3dem] Falcon II uses only half of the 1Gb/s bandwidth.

Hello 3DEM community,

We've noticed that our Falcon II uses only half of the 1Gbps bandwidth to transfer data from the Camera Support Rack to the Microscope PC (I've attached a screenshot to illustrate the issue).

Microscope PC runs Windows 7 and we are able to get the full frame rate (20fps) from the detector, however, it takes ~20s to transfer a typical movie (40frames, 1.2GB) to the PC which is a very frustrating bottleneck.

Both Falcon II and Ceta are connected through the same 1Gb switch (HPE OfficeConnect 1420 24G 2SFP), so my guess is that the bandwidth is split 50/50. However, during data collection only Falcon II is used which makes this limitation pointless, not to mention that Falcon II and Ceta can't be used simultaneously.

Does anyone have a workaround or any info on the topic?


Thanks in advance,
Eugene Pichkur

National Research Centre “Kurchatov Institute”
Akademika Kurchatova, 1, Moscow, Russia, 123098





-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ncmir.ucsd.edu/pipermail/3dem/attachments/20181018/e3ea62f5/attachment.html>