filesystem – Is this a backup format for Mac?

I got sent a hard drive that has this directory and file structure:

./ISB001/NATIVE/000/000/HARP-000000001.pdf
./ISB001/NATIVE/000/000/HARP-000000002.pdf
...
./ISB001/NATIVE/000/000/HARP-000000071.pdf
./ISB001/NATIVE/000/000/HARP-000000072.db
./ISB001/NATIVE/000/000/HARP-000000073.pdf
...
./ISB001/NATIVE/000/000/HARP-000000098.pdf
./ISB001/NATIVE/000/000/HARP-000000099.directoryStoreFile
./ISB001/NATIVE/000/000/HARP-000000100.shadow
./ISB001/NATIVE/000/000/HARP-000000101.indexArrays
./ISB001/NATIVE/000/000/HARP-000000102.indexBigDates
./ISB001/NATIVE/000/000/HARP-000000103.indexDirectory
./ISB001/NATIVE/000/000/HARP-000000104.indexHead
./ISB001/NATIVE/000/000/HARP-000000105.indexIds
./ISB001/NATIVE/000/000/HARP-000000106.indexPostings
./ISB001/NATIVE/000/000/HARP-000000107.indexUpdates
./ISB001/NATIVE/000/000/HARP-000000108.shadowIndexHead
./ISB001/NATIVE/000/000/HARP-000000109.dat
./ISB001/NATIVE/000/000/HARP-000000110.dat
./ISB001/NATIVE/000/000/HARP-000000111.created
./ISB001/NATIVE/000/000/HARP-000000112.modified
./ISB001/NATIVE/000/000/HARP-000000113.pdf
...
./ISB001/NATIVE/000/000/HARP-000000120.pdf
./ISB001/NATIVE/000/000/HARP-000000121.dat
./ISB001/NATIVE/000/000/HARP-000000122.dat
./ISB001/NATIVE/000/000/HARP-000000123.60
./ISB001/NATIVE/000/000/HARP-000000124.2
./ISB001/NATIVE/000/000/HARP-000000125.dat
./ISB001/NATIVE/000/000/HARP-000000126.created
./ISB001/NATIVE/000/000/HARP-000000127.directoryStoreFile
./ISB001/NATIVE/000/000/HARP-000000128.shadow
./ISB001/NATIVE/000/000/HARP-000000129.indexArrays
./ISB001/NATIVE/000/000/HARP-000000130.indexBigDates
./ISB001/NATIVE/000/000/HARP-000000131.indexCompactDirectory
./ISB001/NATIVE/000/000/HARP-000000132.indexDirectory
./ISB001/NATIVE/000/000/HARP-000000133.indexGroups
./ISB001/NATIVE/000/000/HARP-000000134.indexHead
./ISB001/NATIVE/000/000/HARP-000000135.indexIds
./ISB001/NATIVE/000/000/HARP-000000136.indexPositions
./ISB001/NATIVE/000/000/HARP-000000137.indexPostings
./ISB001/NATIVE/000/000/HARP-000000138.shadowIndexGroups
./ISB001/NATIVE/000/000/HARP-000000139.shadowIndexHead
./ISB001/NATIVE/000/000/HARP-000000140.directoryStoreFile
./ISB001/NATIVE/000/000/HARP-000000141.shadow
./ISB001/NATIVE/000/000/HARP-000000142.indexArrays
./ISB001/NATIVE/000/000/HARP-000000143.indexCompactDirectory
./ISB001/NATIVE/000/000/HARP-000000144.indexDirectory
./ISB001/NATIVE/000/000/HARP-000000145.indexGroups
./ISB001/NATIVE/000/000/HARP-000000146.indexHead
./ISB001/NATIVE/000/000/HARP-000000147.indexIds
./ISB001/NATIVE/000/000/HARP-000000148.indexPositions
./ISB001/NATIVE/000/000/HARP-000000149.indexPositionTable
./ISB001/NATIVE/000/000/HARP-000000150.indexPostings
./ISB001/NATIVE/000/000/HARP-000000151.indexTermIds
./ISB001/NATIVE/000/000/HARP-000000152.indexUpdates
./ISB001/NATIVE/000/000/HARP-000000153.shadowIndexArrays
./ISB001/NATIVE/000/000/HARP-000000154.shadowIndexDirectory
./ISB001/NATIVE/000/000/HARP-000000155.shadowIndexGroups
./ISB001/NATIVE/000/000/HARP-000000156.shadowIndexHead
./ISB001/NATIVE/000/000/HARP-000000157.shadowIndexPositionTable
./ISB001/NATIVE/000/000/HARP-000000158.shadowIndexTermIds
./ISB001/NATIVE/000/000/HARP-000000159.dat
./ISB001/NATIVE/000/000/HARP-000000160.dat
./ISB001/NATIVE/000/000/HARP-000000161.2
./ISB001/NATIVE/000/000/HARP-000000162.4
./ISB001/NATIVE/000/000/HARP-000000163.59
./ISB001/NATIVE/000/000/HARP-000000164.dat
./ISB001/NATIVE/000/000/HARP-000000165.shadow
./ISB001/NATIVE/000/000/HARP-000000166.dat
./ISB001/NATIVE/000/000/HARP-000000167.db
./ISB001/NATIVE/000/000/HARP-000000168.updates
./ISB001/NATIVE/000/000/HARP-000000169.Cab
./ISB001/NATIVE/000/000/HARP-000000170.Lion
./ISB001/NATIVE/000/000/HARP-000000171.SnowLeopard
./ISB001/NATIVE/000/000/HARP-000000172.loc
./ISB001/NATIVE/000/000/HARP-000000173.state
./ISB001/NATIVE/000/000/HARP-000000174.plist
./ISB001/NATIVE/000/000/HARP-000000175.plist
./ISB001/NATIVE/000/000/HARP-000000176.pdf

It looks to me like this might be backup format. I suspect that the files were originally grouped into multiple directories, which would be very useful to recover.

The files like with the extensions .directoryStoreFile, .shadow, and .plist suggest that this was originally from a OSX machine. Is this a Mac backup format, and if so, is there a way to recover the original directory structure?