That is a good point about which layers are left unused, however the time lag 
in not including these passes, then requesting a pass that could have been 
included, waiting for it would have a very negative impact on a fast turn 
around project. Far more than having them available anyway. 

On the other point If i needed an extra pass I would expect it to be as a 
separate file regardless of the original delivery. 

Howard

> On 12 Sep 2015, at 9:55 am, Elias Ericsson Rydberg 
> <[email protected]> wrote:
> 
> As a 3D lighter I prefer having it split into multiple files. Sure it's nice 
> to deliver one big exr to comp because then you know all the available 
> channels will show up in nuke. Easy and quick for compositor to bring into 
> the app. Neat.
> 
> But I see a few drawbacks, at least with the way the compositors used the 
> resulting passes. Some would just use the beauty pass and then maybe 
> add/subtract some lighting passes or use a mask or two. Making the majority 
> of the passes redundant But since they were still included, because they 
> might be nice to have, they mostly just caused a strain on the network.
> 
> Albeit this was a few years ago, and exr might have improved since. But even 
> so, when the compositor requested a new special pass. Like a second more 
> broad ambient occlusion pass. It became a bit of a hassle to copy that one 
> pass into the previously delivered main file in nuke and then write out a new 
> main file.
> 
> I know this I deviating from the original topic, which is faster, multipart 
> or monolithic? And the answer is of course "it depends". Does the compositor 
> use all the passes and does the monolith only include the very essentials 
> then that may be the faster route. Do you include a lot of masks and special 
> utility passes, then size of the file grows and the load on the network 
> unnecessary.
> 
> Excuse the long post, and for possibly just stating the obvious.
> 
> Den 12 sep 2015 2:06 fm skrev "Randy Little" <[email protected]>:
>> was Just saying if someone would like I think there has been in depth 
>> discussion about it I believe.  Wasn't meaning to contradict you if it came 
>> off like that.  3 weeks no days off shortest day 13 hours brain left last 
>> week.   
>> 
>> Randy S. Little
>> http://www.rslittle.com/
>> http://www.imdb.com/name/nm2325729/
>> 
>> 
>> 
>>> On Fri, Sep 11, 2015 at 4:37 PM, Nathan Rusch <[email protected]> 
>>> wrote:
>>> Yup, and that's part of what I said. I just wanted to point out that 
>>> multiple file sequences *does* introduce its own form of overhead, but it's 
>>> still almost always the better option.
>>> 
>>>  
>>> From: Randy Little
>>> Sent: Friday, September 11, 2015 4:29 PM
>>> To: Nuke user discussion
>>> Subject: Re: [Nuke-users] Multipart multichannel exrs vs. separate exrs
>>>  
>>> Can't speak to multipart at all but there has always been discussion on the 
>>> list about monolithic multichannel files not being faster in traditional 
>>> networked workflows.  I"m sure I can find the archives and repost those 
>>> results.  (pretty sure actually data)    
>>>  
>>> Randy S. Little
>>> http://www.rslittle.com/
>>> http://www.imdb.com/name/nm2325729/
>>> 
>>> 
>>>  
>>>> On Fri, Sep 11, 2015 at 3:38 PM, Nathan Rusch <[email protected]> 
>>>> wrote:
>>>> It has to *open* the file, yes, but opening does not imply reading.
>>>>  
>>>> One of the main points of a multi-part file is to allow discrete access to 
>>>> each part. As far as I know, hardly any renderers currently support 
>>>> writing multi-part files though, and your 3D guys may not know how to set 
>>>> them up even if they could, so chances are you're looking at 1.x files.
>>>>  
>>>> To partially echo Thorsten, I think in theory multi-part files should be 
>>>> faster than separate file sequences (I say "in theory" because I haven't 
>>>> done any benchmarking of my own).
>>>>  
>>>> Multiple file sequences generally beat monolithic single-part (i.e. 
>>>> multi-layer EXR 1.x) files because of Nuke's selective channel access 
>>>> behavior. In other words, you are rarely reading all of your AOVs at the 
>>>> same time and same place in the node tree, but you are still paying the 
>>>> decompression/read cost for all of them whenever one is read. Incremental 
>>>> improvements to Nuke's caching system may have improved the situation with 
>>>> mutli-layer 1.x files somewhat though.
>>>>  
>>>> On the other side, using multiple sequences trades the 
>>>> "read-and-decompress-everything" requirement for the overhead of requiring 
>>>> Nuke to at least open and read each file's header in order to determine 
>>>> what channels are available (regardless of what channels are actually 
>>>> being read). If you use network storage like most people, this overhead 
>>>> can increase quite a bit due to latency, cluster cache eviction, etc. 
>>>> However, it's still generally better than the alternative.
>>>>  
>>>> On paper, multi-part files should ideally give you the best of both 
>>>> worlds: encapsulation alongside piecemeal data access. To inspect the 
>>>> available channels, Nuke only needs to open a single file, though it will 
>>>> still need to read the header for each part (I'm assuming there's a jump 
>>>> table at the top of the file, but I'm not sure). You can then also seek to 
>>>> and read the data for any one layer without touching data for any others 
>>>> (assuming each is stored in its own part). This relies on smart reader 
>>>> plugin design on the Nuke side, as well as support for parallel access to 
>>>> different parts in the same file.
>>>>  
>>>> -Nathan
>>>> 
>>>>  
>>>> From: Randy Little
>>>> Sent: Friday, September 11, 2015 2:57 PM
>>>> To: Nuke user discussion
>>>> Subject: Re: [Nuke-users] Multipart multichannel exrs vs. separate exrs
>>>>  
>>>> Has to load the file to read it always.   Can't just load part of a little 
>>>> endian file pretty sure.   I know here I can load a beauty pass and scrub 
>>>> it and play around with it and do all kinds of fun things. When some 3d 
>>>> guy decides to put 50 passes (10-15) it take longer to load and they are 
>>>> don't scrub.   
>>>>  
>>>> Randy S. Little
>>>> http://www.rslittle.com/
>>>> http://www.imdb.com/name/nm2325729/
>>>> 
>>>> 
>>>>  
>>>>> On Fri, Sep 11, 2015 at 1:53 PM, Thorsten Kaufmann 
>>>>> <[email protected]> wrote:
>>>>> This is not really true with multipart EXR files anymore. If files are 
>>>>> interleaved by layer rathern than by scanline you loose the benefits but 
>>>>> gain performance compared to multiple sequences. I have yet to do a full 
>>>>> performance check but the boost seems to be rather big if you do not use 
>>>>> all channels (if you use all channels it should not matter anyways, 
>>>>> should it).
>>>>> 
>>>>>  
>>>>> 
>>>>> I expect multichannel to still have some overhead maybe, but given the 
>>>>> downsides of splitting exrs (too many open file handles anyone?) This is 
>>>>> a use case decicsion i would say.
>>>>> 
>>>>>  
>>>>> 
>>>>> Cheers,
>>>>> 
>>>>> Thorsten
>>>>> 
>>>>>  
>>>>> 
>>>>> ---
>>>>> Thorsten Kaufmann
>>>>> Production Pipeline Architect
>>>>> 
>>>>> Mackevision Medien Design GmbH
>>>>> Forststraße 7
>>>>> 70174 Stuttgart
>>>>> 
>>>>> T +49 711 93 30 48 606
>>>>> F +49 711 93 30 48 90
>>>>> M +49 151 19 55 55 02
>>>>> 
>>>>> [email protected]
>>>>> www.mackevision.com
>>>>> 
>>>>> Geschäftsführer: Armin Pohl, Joachim Lincke
>>>>> HRB 243735 Amtsgericht Stuttgart
>>>>> 
>>>>> ---
>>>>> VFX: Game of Thrones, Season 5 – VFX making of reel.
>>>>> TWITTER | ADOBE BEHANCE: Follow us on Twitter and Adobe Behance.
>>>>> 
>>>>>       
>>>>> Von: [email protected] 
>>>>> <[email protected]> im Auftrag von Randy Little 
>>>>> <[email protected]>
>>>>> Gesendet: Freitag, 11. September 2015 22:06
>>>>> An: Nuke user discussion
>>>>> Betreff: Re: [Nuke-users] Multipart multichannel exrs vs. separate exrs
>>>>>  
>>>>> big huge all passes in a exr is slow.   Has to read entire file (75MB+) 
>>>>> to find the channel you want that might be 200KB every      single time 
>>>>> you want to deal with that little mask channel.   They also seem to take 
>>>>> longer to render out of 3d.   We usually break them up by math type and 
>>>>> try not to stuff 20 passes into a file.  
>>>>>  
>>>>> Randy S. Little
>>>>> http://www.rslittle.com/
>>>>> http://www.imdb.com/name/nm2325729/
>>>>> 
>>>>> 
>>>>>  
>>>>>> On Fri, Sep 11, 2015 at 2:31 AM, Johannes Hezer 
>>>>>> <[email protected]> wrote:
>>>>>> Hey everyone,
>>>>>> 
>>>>>> A bit of a survey question... Is anyone using multipart exrs ?
>>>>>> We have been using them for 2 projects and we have not done any 
>>>>>> performance profiling, but I am not 100% sure if it is a speed bost or 
>>>>>> not, compared to multichannel 1.xxx exrs.
>>>>>> I was hoping might come close to splitted exrs (each layer in a single 
>>>>>> file) ...
>>>>>> 
>>>>>> Looking forward to some input
>>>>>> 
>>>>>> Cheers
>>>>>> Johannes
>>>>>> 
>>>>>> Von meinem iPhone gesendet
>>>>>> 
>>>>>> ____ ESET 12236 (20150911) ____
>>>>>> The message was checked by ESET Mail Security.
>>>>>> 
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>>>>>  
>>>>> 
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