Past time to run Backup Bouncer on my Synology store-everything plan!
./bbouncer create-vol Src
./bbouncer create /Volumes/Src
sudo /usr/local/bin/rsync -aAHNX --delete --stats /Volumes/Src/ /Volumes/NetworkShare/Dst-rsync1
Number of files: 69
Number of files transferred: 26
sent 4621 bytes  received 655 bytes  2110.40 bytes/sec
total size is 365  speedup is 0.07
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1039) [sender=3.0.6]
sudo ./bbouncer verify -d /Volumes/Src /Volumes/NetworkShare/Dst-rsync1
Verifying:    basic-permissions ... FAIL (Critical)
Verifying:           timestamps ... stat: ./some-file: stat: No such file or directory
FAIL (Critical)
Verifying:             symlinks ... ok (Critical)
Verifying:    symlink-ownership ... FAIL 
Verifying:            hardlinks ... stat: link1: stat: No such file or directory
stat: link2: stat: No such file or directory
stat: link3: stat: No such file or directory
FAIL (Important)
Verifying:       resource-forks ... 
grep: ./some-file/rsrc: Not a directory
   Sub-test:             on files ... FAIL (Critical)
   Sub-test:  on hardlinked files ... FAIL (Important)
Verifying:         finder-flags ... ok (Critical)
Verifying:         finder-locks ... FAIL 
Verifying:        creation-date ... ok 
Verifying:            bsd-flags ... ok 
Verifying:       extended-attrs ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:       on directories ... FAIL (Important)
   Sub-test:          on symlinks ... FAIL 
Verifying: access-control-lists ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:              on dirs ... FAIL (Important)
Verifying:                 fifo ... FAIL 
Verifying:              devices ... FAIL 
Verifying:          combo-tests ... 
   Sub-test:  xattrs + rsrc forks ... FAIL 
   Sub-test:     lots of metadata ... FAIL 
sudo /usr/local/bin/rsync -aAHNX --delete --fileflags --force-change --stats /Volumes/Src/ /Volumes/NetworkShare/Dst-rsync2
Number of files: 69
Number of files transferred: 26
sent 4664 bytes  received 655 bytes  2127.60 bytes/sec
total size is 365  speedup is 0.07
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1039) [sender=3.0.6]
sudo ./bbouncer verify -d /Volumes/Src /Volumes/NetworkShare/Dst-rsync2
Verifying:    basic-permissions ... FAIL (Critical)
Verifying:           timestamps ... stat: ./some-file: stat: No such file or directory
FAIL (Critical)
Verifying:             symlinks ... ok (Critical)
Verifying:    symlink-ownership ... FAIL 
Verifying:            hardlinks ... stat: link1: stat: No such file or directory
stat: link2: stat: No such file or directory
stat: link3: stat: No such file or directory
FAIL (Important)
Verifying:       resource-forks ... 
grep: ./some-file/rsrc: Not a directory
   Sub-test:             on files ... FAIL (Critical)
   Sub-test:  on hardlinked files ... FAIL (Important)
Verifying:         finder-flags ... ok (Critical)
Verifying:         finder-locks ... ok 
Verifying:        creation-date ... ok 
Verifying:            bsd-flags ... ok 
Verifying:       extended-attrs ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:       on directories ... FAIL (Important)
   Sub-test:          on symlinks ... FAIL 
Verifying: access-control-lists ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:              on dirs ... FAIL (Important)
Verifying:                 fifo ... FAIL 
Verifying:              devices ... FAIL 
Verifying:          combo-tests ... 
   Sub-test:  xattrs + rsrc forks ... FAIL 
   Sub-test:     lots of metadata ... FAIL 
One thing to note is that I need --fileflags with rsync to pass the finder-locks test; other than that the two rsync results look the same. Without the errors, those results are:
Verifying:    basic-permissions ... FAIL (Critical)
Verifying:           timestamps ... FAIL (Critical)
Verifying:             symlinks ... ok (Critical)
Verifying:    symlink-ownership ... FAIL 
Verifying:            hardlinks ... FAIL (Important)
Verifying:       resource-forks ... 
   Sub-test:             on files ... FAIL (Critical)
   Sub-test:  on hardlinked files ... FAIL (Important)
Verifying:         finder-flags ... ok (Critical)
Verifying:         finder-locks ... ok 
Verifying:        creation-date ... ok 
Verifying:            bsd-flags ... ok 
Verifying:       extended-attrs ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:       on directories ... FAIL (Important)
   Sub-test:          on symlinks ... FAIL 
Verifying: access-control-lists ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:              on dirs ... FAIL (Important)
Verifying:                 fifo ... FAIL 
Verifying:              devices ... FAIL 
Verifying:          combo-tests ... 
   Sub-test:  xattrs + rsrc forks ... FAIL 
   Sub-test:     lots of metadata ... FAIL 
Or, paring it down to failed tests,
Verifying:    basic-permissions ... FAIL (Critical)
Verifying:           timestamps ... FAIL (Critical)
Verifying:    symlink-ownership ... FAIL 
Verifying:            hardlinks ... FAIL (Important)
Verifying:       resource-forks ... 
   Sub-test:             on files ... FAIL (Critical)
   Sub-test:  on hardlinked files ... FAIL (Important)
Verifying:       extended-attrs ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:       on directories ... FAIL (Important)
   Sub-test:          on symlinks ... FAIL 
Verifying: access-control-lists ... 
   Sub-test:             on files ... FAIL (Important)
   Sub-test:              on dirs ... FAIL (Important)
Verifying:                 fifo ... FAIL 
Verifying:              devices ... FAIL 
Verifying:          combo-tests ... 
   Sub-test:  xattrs + rsrc forks ... FAIL 
   Sub-test:     lots of metadata ... FAIL 
The NetworkShare volume is a Synology RS-407 running an embedded Linux mounted via AFP (AppleShare). The permission problems (and ownership and hardlinks and resource forks and ACLs) might be how it's mounted, but I'm concerned about those extended attributes. Might be time to ask Google and friends ...