# DNG and sidecars XMP



## ario (Feb 13, 2012)

I have to deal with several DNG native files from Leica, Ricoh and Pentax and I wish to keep metadata such as keywords, geotags... in sidecar XMP's for easy transportation and use in other programs (CO for instance). Unfortunately LR does not allow me to write metadata in a sidecar outside the DNG (which is possible with other raw formats) and this means that for any modification to a single metadata I have to backup the entire DNG file. Any idea, suggestion...?
Ario


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## johnbeardy (Feb 13, 2012)

Why do you have to backup the entire DNG again? It's a common myth though. Writing to DNG is safe by comparison with writing directly into a proprietary raw file. With a backup of the virgin DNG and the catalogue, you have 100% backup of your Lightroom work. Your extra backups are only a second-rate backup - missing plenty of what you do in Lightroom. You would also get compatibility issues with other program's that assume that publicly- documented files like DNGs, TIFs, JPEGs will have metadata inside them, not in sidecars. I really don't think it will happen!


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## ario (Feb 13, 2012)

John,
In each of my dedicated HD's (main & backups) I have a copy of the raw files (mostly native DNG's) and of the LR catalog. As a routine I perform an incremental backup of my dedicated HD's (main into backup_1 and backup_2) so that they are all syncronize in respect to raw's and to catalog.
In this way every time I change a metadata I force the backup to include e new complete DNG file, not just the XMP as I would prefer and as it is possibe with any other raw file format. May be I'm doing something wrong but so far I have not found any better way. 
Thanks,
Ario


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## Kiwigeoff (Feb 13, 2012)

Ario, in Catalog Settings>Metadata, turn off the Autowrite to xmp and Lightroom will not up date the DNG files, adjustments will be kept only in the catalog unless you cmd-s to save changes to files. Then the DNG's should not need backing up incrementally.


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## johnbeardy (Feb 13, 2012)

My approach is to think of DNGs as "virgin" and "working". When a DNG is first created, it is on one drive which is backed up to a hard drive which is usually kept offline, and to a DVD (the value of DVD being a write-once media should not be overlooked). So I have an archive of "virgin" DNGs, and daily backups of the catalogue. The DNG copy that is in Lightroom is _only_ a "working" DNG and is on a drive which is not backed up, no matter how much I save metadata back into the DNG.

Now let's say my catalogue fails - I restore its backup. Or say my working DNG drive crashes - I restore my _virgin_ DNGs. In either case, I'm 100% covered. 

I really don't believe Adobe is likely to change this, so I think people need to reconsider backup strategies so they take advantage of DNGs - not see their existing backup practices as a reason to avoid the format.

John


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## ario (Feb 13, 2012)

Thak you John anf Geoff,
what you say is perfctly fine as long as I use the raw (DNG) files only in Lightroom or CS. My desire to have workable sidecars also witn DNG's is because some of my files are also been developed in CO.
If this was not the case I would keep the metadata inside the catalog without esitation and I would not have any issue about redundant backup.
As suggested I will think about a different backup strategy.
Ario


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## LouieSherwin (Feb 13, 2012)

Hi Ario,

You have stumbled across one of the challenges of a DNG workflow, any change to any information in the file causes a complete rewrite of the entire file and as you have noticed, another backup. Lightroom as provided a workaround for this by holding all the metadata in the catalog so that every little tweak of develop sliders or keyword entry etc. do not keep rewriting the DNG file. 

I don't think that the same can be said for working in CS. By that I am assuming that you mean Photoshop CS5 and for DNG files that really means Adobe Camera Raw and Bridge. Any edits you do on a DNG using either of those tools directly, meaning not using edit in from Lightroom, will also rewrite the DNG file and trigger a backup. 

One possible solution for how to share up to date metadata without triggering unnecessary copying and backups might be to use a Publish collection to publish selected originals to a folder on your hard drive where CaptureOne would then use as the input. I am not completely sure but I think that if you publish the original, Lightroom will also export the metadata from the catalog with the copy in the export folder. 

Also, I like your idea of using XMP sidecar files with DNG as well a native raw. I think it makes a lot of sense when working in a editing environment. Conceptually it is really no different than what is already happening in Lightroom. It is just that now the sidecar for DNG files is currently being stored in the database instead of on your hard drive.  Too bad that they don't provide the option to do both.

-louie


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## clee01l (Feb 13, 2012)

Think of these DNGs as a TIFF file (which they are) or a JPEG (which they are not). In these two or three non proprietary file formats LR writes the metadata to the file header because it it it most efficient for retrieving this information and because LR can do so non destructively If this were possible for the proprietary RAW formats, LR would never have to create a sidecar file. 
I use a Pentax too. MySOOC RAW files are DNG too. For a long time, I diligently kept my DNG file metadata up to date with LR, The overhead associated with backing up a changed DNG is not significant. I'm sure it is more than just updating a small XMP file,  but it is a price that you need to pay if you want the other advantages that LR provides. 

If you have multiple computers on a network, and want to access a DNG from any of these computers, why not keep one and only one master copy of the DNG on a NAS accessible to all computers and all applications.  While LR does not have the capability to permit you to keep a active catalog on a network drive, you can keep all of your master image copies on a network drive and manage them in your local LR master catalog.  With one copy of the master image file, you only need to back up the NAS drive.


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