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[lalittle]

I've noticed for a while now (going back to MC11) that when I backup my library, I get very different file sizes.  I'll back up the library once, and the filesize will be around 8 megs.  I'll then close MC12 and open it again, then immediately do another backup.  Even though NOTHING has changed, the second backup will only be about 2.5 megs.  I looked over my past backups, and I see some as large as 35 megs.

This has me worried since I am not sure if my backups are okay.  Why would two consecutive backups (one made after restarting MC) be such different sizes even though nothing in the library had changed?

Thanks,

Larry

[Hugo_Elbuho]

Hey!!  It's true!...  can confirm that and second your worries.

[lalittle]

Thanks for confirming this Hugo.

It seems like the smaller file sizes are the "normal" ones, and that the longer MC is open, the more likely it is to create much larger backup files.

I also notice that the size of the library the client loads over Media Server will change quite a bit.  Sometimes it's a couple megs, while other times it's 7 or 8 megs even though it's the exact same library.

Larry

[marko]

I'm not seeing this.
I'm not using library server.
all my backups, including following your steps, are in the 12.8 meg area (zipped - 24 megs expanded). The two I made during testing just now were the same size (12.8 megs).
The largest file i have is lyrics.jmd @ 4.8 megs, followed by name.jmd and bios.jmd @ 3 megs and 2.4 megs respectively.

What files inside the zips are causing the difference in size? Once you've id'd them, I'm willing to bet you're half way to an explanation.

[Hugo_Elbuho]

Well, i gave testing a second try.

I couldn't reproduce the 1 meg change (aproximately) i had this morning in two consecutive backups (10 secs aprox between them) without playing back.

What happened now is what is obvious: if you play a couple of songs, the playlistx.jmd will change and therefore some playlists will change so backups won't be exact same size.

Second observation is perhaps the most interesting:

I have concluded that sometimes the compression algorithm shows different effective compression ratios for the very same files and filesizes.    If someone could teach me how to post an image i have them ready to show my point

Thanks!

[marko]

How to display an image in a forum posting courtesy of Romulus2

Romulus2 was shaping up to be a great internet rescource a few years ago, but alas, has become a ghost site

[Hugo_Elbuho]

First backup:



Second one:



Notice the original filesizes and how the compresion rate changes from file to file.  I have highlighted just one of them.  Maybe that could be the reason for the backup size change.

[lalittle]

What files inside the zips are causing the difference in size? Once you've id'd them, I'm willing to bet you're half way to an explanation.

I took a look at the zipped files.  What Hugo suggested about the Playing Now playlist makes sense, but unfortunately this doesn't appear to be what I'm seeing.  On my systems, the sizes of a LOT of the "field..." files change between the backups.  Not "all" of them, but quite a few of them.

Note that the pattern appears to be that MC needs to have been running for a while for this to happen.  If I just run consectutive backups, the sizes are the same.  Note also that I AM running Media Server, so perhaps this is related to the behavior that Hugo and I are seeing.

Any idea why the sizes of these "field..." files would change even though nothing had changed in MC?  All I did was close and open the program, and run another backup.

Thanks again,

Larry

[Matt]

It's nothing to worry about.  Working records get added and removed from the MC database all the time as you use it.  (for handhelds, podcasts, browsing, etc.)

[lalittle]

It's nothing to worry about.  Working records get added and removed from the MC database all the time as you use it.  (for handhelds, podcasts, browsing, etc.)

Thanks for the explanation.  I just wanted to make sure that nothing was "corrupt."

Larry