2 added KingKongFrog's answer to mine.
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I wonder if you are hitting the max file count for the destination directory? In a classic Unix file system like ext2, you have a limit of 32,000 (2^15) files (or sub-directories or links (things)) per directory. A Time Machine backup is a sparse disk image, which is a bunch of 8MB files. 300GB of 8MB files is something like 37,000. Ooops.

You can increase the size of the files that Time Machine uses in the sparse bundle (these instructions would increase the max size of your backup by 16), or change the file system on the NAS, Reiserfs, ext4 (some versions of ext3), etc, probably will work, if this is the issue.

User KingKongFrog added this answer, I'm adding it to my answer (but upvote his as well), this lets you convert your existing backup to the larger size

hdiutil convert MyMac_001acb9cb23d.sparsebundle -format UDSB -tgtimagekey sparse-band-size=2097152 -o NEW_MyMac_001acb9cb23d.sparsebundle

link to the blog I got this from

# creates a sparsebundle disk image with a 128MB band size
MACHINE_NAME=your-machine-name
echo $MACHINE_NAME
hdiutil create -size 900g -type SPARSEBUNDLE -nospotlight -volname "Backup of $MACHINE_NAME" -fs "Case-sensitive Journaled HFS+" -imagekey sparse-band-size=262144 -verbose ./$MACHINE_NAME.sparsebundle

# copy the plists from TIME_MACHINE_IMAGE to NEW_IMAGE
TIME_MACHINE_IMAGE=your-machine-name.old.sparsebundle
NEW_IMAGE=your-machine-name.sparsebundle
cp $TIME_MACHINE_IMAGE/com.apple.TimeMachine.*.plist $NEW_IMAGE

I wonder if you are hitting the max file count for the destination directory? In a classic Unix file system like ext2, you have a limit of 32,000 (2^15) files (or sub-directories or links (things)) per directory. A Time Machine backup is a sparse disk image, which is a bunch of 8MB files. 300GB of 8MB files is something like 37,000. Ooops.

You can increase the size of the files that Time Machine uses in the sparse bundle (these instructions would increase the max size of your backup by 16), or change the file system on the NAS, Reiserfs, ext4 (some versions of ext3), etc, probably will work, if this is the issue.

link to the blog I got this from

# creates a sparsebundle disk image with a 128MB band size
MACHINE_NAME=your-machine-name
echo $MACHINE_NAME
hdiutil create -size 900g -type SPARSEBUNDLE -nospotlight -volname "Backup of $MACHINE_NAME" -fs "Case-sensitive Journaled HFS+" -imagekey sparse-band-size=262144 -verbose ./$MACHINE_NAME.sparsebundle

# copy the plists from TIME_MACHINE_IMAGE to NEW_IMAGE
TIME_MACHINE_IMAGE=your-machine-name.old.sparsebundle
NEW_IMAGE=your-machine-name.sparsebundle
cp $TIME_MACHINE_IMAGE/com.apple.TimeMachine.*.plist $NEW_IMAGE

I wonder if you are hitting the max file count for the destination directory? In a classic Unix file system like ext2, you have a limit of 32,000 (2^15) files (or sub-directories or links (things)) per directory. A Time Machine backup is a sparse disk image, which is a bunch of 8MB files. 300GB of 8MB files is something like 37,000. Ooops.

You can increase the size of the files that Time Machine uses in the sparse bundle (these instructions would increase the max size of your backup by 16), or change the file system on the NAS, Reiserfs, ext4 (some versions of ext3), etc, probably will work, if this is the issue.

User KingKongFrog added this answer, I'm adding it to my answer (but upvote his as well), this lets you convert your existing backup to the larger size

hdiutil convert MyMac_001acb9cb23d.sparsebundle -format UDSB -tgtimagekey sparse-band-size=2097152 -o NEW_MyMac_001acb9cb23d.sparsebundle

link to the blog I got this from

# creates a sparsebundle disk image with a 128MB band size
MACHINE_NAME=your-machine-name
echo $MACHINE_NAME
hdiutil create -size 900g -type SPARSEBUNDLE -nospotlight -volname "Backup of $MACHINE_NAME" -fs "Case-sensitive Journaled HFS+" -imagekey sparse-band-size=262144 -verbose ./$MACHINE_NAME.sparsebundle

# copy the plists from TIME_MACHINE_IMAGE to NEW_IMAGE
TIME_MACHINE_IMAGE=your-machine-name.old.sparsebundle
NEW_IMAGE=your-machine-name.sparsebundle
cp $TIME_MACHINE_IMAGE/com.apple.TimeMachine.*.plist $NEW_IMAGE
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1
source | link

I wonder if you are hitting the max file count for the destination directory? In a classic Unix file system like ext2, you have a limit of 32,000 (2^15) files (or sub-directories or links (things)) per directory. A Time Machine backup is a sparse disk image, which is a bunch of 8MB files. 300GB of 8MB files is something like 37,000. Ooops.

You can increase the size of the files that Time Machine uses in the sparse bundle (these instructions would increase the max size of your backup by 16), or change the file system on the NAS, Reiserfs, ext4 (some versions of ext3), etc, probably will work, if this is the issue.

link to the blog I got this from

# creates a sparsebundle disk image with a 128MB band size
MACHINE_NAME=your-machine-name
echo $MACHINE_NAME
hdiutil create -size 900g -type SPARSEBUNDLE -nospotlight -volname "Backup of $MACHINE_NAME" -fs "Case-sensitive Journaled HFS+" -imagekey sparse-band-size=262144 -verbose ./$MACHINE_NAME.sparsebundle

# copy the plists from TIME_MACHINE_IMAGE to NEW_IMAGE
TIME_MACHINE_IMAGE=your-machine-name.old.sparsebundle
NEW_IMAGE=your-machine-name.sparsebundle
cp $TIME_MACHINE_IMAGE/com.apple.TimeMachine.*.plist $NEW_IMAGE