[Halld-offline] Fwd: Re: Gluex event sizes in pythia MC

[Richard Jones]

Sorry, this message did not go to the full list.  Here it is.

-Richard J.

-------- Original Message --------
Subject: 	Re: Gluex event sizes in pythia MC
Date: 	Wed, 27 Oct 2010 11:09:13 -0400
From: 	Richard Jones <richard.t.jones at uconn.edu>
To: 	Heyes Graham <heyes at jlab.org>
CC: 	Lawrence David <davidl at jlab.org>, Mark Ito M. <marki at jlab.org>



Graham and all,

We do not have a number on the encoding ratio between coda and hddm, but I believe that the two should be within 30% of each other for the identical set of hits being recorded.  The big effect -- we are looking at a factor 3.5 -- lies in the thresholds that are used to define what gets called a hit.  Matt points out that these thresholds are deliberately set artificially low in Monte Carlo so that we can add fluctuations later.  A better estimate for event sizes might be obtained by looking at the events coming out of mcsmear, after applying more realistic hit thresholds to those events to see what we get.

Matt, do we have the necessary information about what those thresholds should be in order to allow me to carry out this exercise?

-Richard J.



On 10/27/2010 8:35 AM, Heyes Graham wrote:
>  Ok, after further digestion of coffee, it's still early, I would hazard a guess that the critical phrase in Alex's email is:
>
>  The number of bytes used to code hdgeant and coda records is different.
>
>  Is the 50kb quoted in Richard's email hdgeant format and what is the scaling factor between the two formats? i.e. is the 15 kb for CODA format raw data still valid?
>
>  Thanks,
>  Graham
>
>  On Oct 27, 2010, at 8:16 am, Heyes Graham wrote:
>
>  Hi Folks,
>  Chip just forwarded this email thread to me. He is, correctly, raising concern about the event size of 50kb quoted for minimum bias samples. The online event size that we have been working with for both offline and online planning is 15kb. A factor of three increase in event size would have real world consequences in terms of both online and offline computing and tape storage.
>
>  Can you please clarify what the expected average event size for GLUEX is.
>
>  Regards,
>  Graham
>
>  Begin forwarded message:
>
>  From: Chip Watson<watson at jlab.org<mailto:watson at jlab.org>>
>  Date: October 27, 2010 8:00:04 am EDT
>  To: Graham Heyes<heyes at jlab.org<mailto:heyes at jlab.org>>
>  Subject: [Fwd: Re: [Halld-offline] Gluex event sizes in pythia MC]
>
>  Graham,
>
>  Do these event size changes imply anything interesting for offline computing?
>
>  Chip
>
>  From: Alexander Somov<somov at jlab.org<mailto:somov at jlab.org>>
>  Date: October 27, 2010 1:38:48 am EDT
>  To: Richard Jones<richard.t.jones at uconn.edu<mailto:richard.t.jones at uconn.edu>>
>  Cc: HallD Software Group<halld-offline at jlab.org<mailto:halld-offline at jlab.org>>
>  Subject: Re: [Halld-offline] Gluex event sizes in pythia MC
>
>
>  Hello Richard, all,
>
>  The HDgeant event size estimates are definitively very useful.
>
>  There was a kind of confusion during the meeting regarding the
>  event size in daq (I forgot who came up with this question);
>  i just want to clarify on this point once again:
>  - for the daq event size we consider hit multiplicities of
>     events accepted by the level1 trigger and multiply these mult.
>     by the number of bits needed to code the time/integral of
>     f1tdc's and flash adc's (+ add headers). To get
>     an average event size one needs to take a (rate) weighted
>     sum of the em background and hadronic events. The number
>     of bytes used to code hdgeant and coda records is
>     different.
>
>  The event size is indeed dominated by the FDC.
>
>  Cheers,
>          Alex
>
>
>
>  On Tue, 26 Oct 2010, Richard Jones wrote:
>
>  Hello,
>
>  As I pointed out during our Monday physics meeting, event sizes for pythia
>  minimum-bias samples are right now around 50kb.  I have made the event record
>  distributions, grouped by detector and type of information stored, and posted
>  them on the web page below.  The FDC is the largest contributor, at around
>  75% of the total payload.
>
>  http://zeus.phys.uconn.edu/halld/hdgeant/sizes-10-2010
>
>  -Richard Jones
>
>
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>
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