Thanks for answering
Em qua, 2022-02-16 às 13:39 -0500, backu...@kosowsky.org escreveu:
> brogeriofernan...@gmail.com wrote at about 15:21:10 -0300 on
> Wednesday, February 16, 2022:
> > Hi everyone
> >
> > Currently, I'm using urbackup to backup a lot of image files and
> > thinking of migrating to backuppc.
> >
> > I'm wondering if would be possible to run a command just after
> client
> > transfers file data but before it's stored in backuppc pool. My
> idea is
> > to do an image compression, like jpeg-xl lossless, instead of the
> > standard zlib one.
>
> That capability does not (yet) exist.
> Currently, BackupPC only supports zlib compression (or no
> compression)
> and even the level of the compression is not variable between files
> on
> a given backup (and frankly, compression is typically set uniformly
> for all hosts and backups for pooling consistency).
>
> The ability to have a per-file option to specify compression type is
> an interesting feature request -- but would require some significant
> rearchitecting to:
>
> 1. Create logic after the file transfer to decide what compression to
> use, potentially based on a number of different possible criteria.
> e.g., file extension, file size, regexp match on file name, file
> type...
> To do it right would add a fair bit of complexity and depending on
> the test could slow down backups
>
> 2. Decide on how to associate the compression type with the file.
>
> If this is done at the pool file level (as part of a header or
> Magic number), then you may run into problems if for the same file
> content, there is conflicting choices of compression (this could
> happen between hosts or even for the same host if the files have
> the same content but different names, for example)
>
> If this is done at the backup level by adding an entry to the
> attrib file, then you have a similar problem of conflicting
> compression directions for the same pooled file content.
>
>
> 3. Have a way to pass code (perl interpreted code? perl code stub?
> command line function call) to do the compression.
In my use-case I wouldn't need to check file type as I'm backing up
just JPEG files, but you made I good point and it would be a more
complete solution that way.
>
> > Reading the docs, I couldn't find any mention to specifying a
> command
> > to run before storing data, just commands to run before or after a
> > backup is done as a whole (eg. $Conf{DumpPreUserCmd},
> > $Conf{DumpPostUserCmd})
>
> True
>
>
> > Maybe one option would be to convert and keep both versions of
> files,
> > JPEG and JPEG-XL, on client, but it's inviable to me because
> currently
> > I have about 15TB of images and don't have enough room to keep
> both of
> > them.
>
> That is the best way.
>
> >
> > So, the steps I'm thinking of would be to transfer the files from
> > client to server as usual but, just before storing them in the
> pool,
> > running a command (in this case, cjxl) to do an image compression.
> Doing this right is not so simple as outlined above.
> Though the code is open source and you are encouraged to submit
> patches to do what you want here.
I would love to implement this feature, but honestly, I don't have any
clue where to start. So, as this feature doesn't exist, probably I'll
dig into sources to figure out how can I do that.
> > Certainly, this would be more bandwidth-friendly if it was
> possible to
> > do this compression before transferring to server, but I can't
> figure
> > out how I could accomplish this.
> Presumably harder as it would require host-side code to do things
> such as running a patched host version of rsync (or other transfer
> method executable)
> >
> > Any thoughts on this?
> >
> > Many thanks
> >
> >
> > _______________________________________________
> > BackupPC-users mailing list
> > BackupPC-users@lists.sourceforge.net
> > List:
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> > Wiki: https://github.com/backuppc/backuppc/wiki
> > Project: https://backuppc.github.io/backuppc/
>
>
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