What to keep NEF & xmp and psd?

Hello Popcorn. PhotoFrank has given some good suggestions. Out of interest are you using the full PS or PS Elements?

Here are some more suggestions I can think of.

1- Delete any layers in the psd file you don't need, and as PhotoFrank has suggested convert to 8 bit with AdobeREGB or sRGB if they are not already 8 bit.

2- On the top layer put a solid colour adjustment layer and set to white. This will reduce the file size a bit by removing the embedded jpg preview in the psd file.

www.imaging-resource.com/news/2015/02/11/did-you-know-placing-a-blank-white-layer-atop-a-.psd-can-cut-the-file-size#:~:text=The%20reason%20this%20reduces%20the,the%20preview%20file%20size%20issue.


Kind regards
Chris

For what it is worth .... 
I have 18 hard drives totally perhaps 40 TB of a capacity. (...two, 8 Tbs and three or four, 5 TBs plus smaller ones.) Some of the older drives are approaching ~20 years old. One new one failed but I had double back ups for 90% on that drive. I digress ... 
I save edited raw files and the small xmp files. I am quite aggressive at deleting (forever) unedited files....thousands annually. I do major deletions every new month. I figure if they were not good enough to edit and consider for saving today, then I won't be checking them again next year. (I recently took over 900 photos of flying osprey in about 30 minutes. Some here. I went through them and edited about 40 of them. I checked the unedited photos again. On about August 1, I will go through all of July's photos and delete forever unedited images, including ~800 osprey photos.) 

If you have the edited raw files I see no reason to save PSD files. The only PSD files I save are ones that have critical editing layers (say, masking) or "posters" that have text layers or several inset images. I save all of my forever photos as jpgs at max quality i.e. zero/low compression. (The edited raw files are saved as well.) 

(Side note: My first hard drive ca 1985 weighted about 3 kg and the size of a shoe box. It stored 10 Mb. HA HA. I'd need more than 3,000 of these drives to store just the July 4 osprey photos.)  

Clive  

Hi all, and thank you.
I apologize for the delayed response. Iam recovering from the worst flu I have ever had ( Covid? ) and am still finding it difficult to think rationally.

I am using Elements 2023 and Elements+
The reason that I want to keep all the information is that I live in hope that I will return one day and be able to release the full potential of a "forgotten Gem".

I call working in ACR processing and working in elements and layers, editing. I am now 83 and my memory has never been good and is now atrocious. I have to summarize on Word every article or tutorial I feel I may find useful. Unfortunately I do not have full ACR.

Frank,
I use .psd because want to reproduce my previously edited image exactly.
As far as I know Elements does not have the facility to Zip the .psd files. Do you do this with an external program, and if so, is there any loss of information after compression?
.tif files seem to have the most options in file size but I never use them and don't know if they retain all the .psd information and whether the image is identical to the .pdf in all respects.
Does an embedded jpg image serve in a saved .pdf file? The thumbnail does not show it.

Chris,
because I use Elements and most of its functions require 8 bit images, most of my saved files are 8bit.
I am never quite sure which of the layers can be removed, some of the them may have no effect on the final image but are steps in the edit.
I have never been able to tell the difference between 12 & 8 bit images on a computer screen or a A4 print.
I will try your solid white layer.

Hi Clive,
I try to be ruthless in my deletion files not worthy of eiteing, I only keep the "special occasion" ones.

Hi Andrei,
Its always the 'pdf file that become so big anyway.

Thanks everyone for your help.

Thanks Vicki,
I always convert any files that I send to others to jpg just on the basis of file size.
I have been asked to supply TIF files on occasion and have always found them to be of similar size to the PSD.

Hi Buckskin,
Try living in South Africa where a $ costs nearly R20!!! and all technology is subject to heavy customs taxes. I remember the days when R1 bought $1,5. Travelling to the USA was a cheap holiday!!

Your advice has really hit home. It brought back memories and I thought this may be interesting.

My Dad was a keen photographer. He was a professional Engineer and had a friend who was a Chemist and they must have been one of the first to use colour processing in South Africa. They lived in Durban, a port on the mailship line between South Africa and the UK. They used friends, working on these ships, to import photographic material. They experimented with both Kodachrome and Agfacolour, they did their own processing. Agfacolour was released in 1936, Kodachrome 35mm in 1937 but I am not sure when the 120 colour negative film, used by my father, was introduced.

My Mom died in her late twenties in September 1940, I still have a colour negative of her which must have been taken circa 1939. This must be one of the first colour images taken in South Africa.
I can't find a print.

Apropos your advice, all I have to do is open one of the many photo albums my father left behind, and his memories are all there, including my mother, who I never saw.
Hundreds of tiny B&W images ( I have only found one colour negative ), he must have developed, printed and placed nearly every photograph he took into albums.
The only clue to the identity, time and place are in pencil notes, made by my mother, on the backs of each print. My mother only exists for me in those albums.

What a difference! My descendants will inherit my memories in the form of thousands of undecipherable digital files, all neatly Organized, with Tabs for date, name, occasion and place, but no way of knowing how to unlock the contents!!!

I only print my best images, never smaller than A5. I guess I am about to change my ways, I have forgotten that, for most people, the most important function of photography is too record the past and memories.

My printer is going to run hot producing lots of 100 x 70mm indifferent images. Thank you for reminding me.

I hope this is not out of place here, if so, I apologize.