Strange rsync samba btrfs behavior by Files lesser than 26MB

i have created a btrfs filesystem on my Raspberry Pi with a simple subvolume Data01, to share for backup my Server i've created a samba share on raspberry

After that i mounted the samba share on my ubuntu 20.04 Server by fstab and tried to rsync some files from server to raspi

At first look it works fine, but on a second sync it looked like rsync copies all Files again I've never used rsync before, so i added a large file (3.2GB ISO) to my folder on server and it would copy only once but smaller files would be copied everytime

So my next thing was to check on which file size rsync stopps to copy files everytime And it looks like 26MB

So after that i looked with stats and i could see that smaller Files dosen't have correct time values

 Datei: Zwergentrunk-1.pdf Gr▒▒e: 740838 Bl▒cke: 1448 EA Block: 4096 regul▒re Datei Ger▒t: 2eh/46d Inode: 4917 Verkn▒pfungen: 1 Zugriff: (0744/-rwxr--r--) Uid: ( 1001/srvbackup) Gid: ( 1001/srvbackup) Zugriff : 2022-04-06 21:16:26.471913500 +0200 Modifiziert: 2022-04-06 21:16:26.563488588 +0200 Ge▒ndert : 2022-04-06 21:16:26.557414539 +0200 Geburt : - 

But Larger File

Datei: ubuntu-20.04.4-desktop-amd64.iso Gr▒▒e: 3379068928 Bl▒cke: 6599744 EA Block: 4096 regul▒re Datei Ger▒t: 2eh/46d Inode: 4911 Verkn▒pfungen: 1 Zugriff: (0744/-rwxr--r--) Uid: ( 1001/srvbackup) Gid: ( 1001/srvbackup) Zugriff : 2022-04-06 18:40:32.667789400 +0200 Modifiziert: 2022-03-20 23:29:45.304778200 +0100 Ge▒ndert : 2022-04-06 18:40:36.193852990 +0200 Geburt : - 

I hope someone has any Idea, best regards

fstab on raspi (shortened)

UUID=1483d2ca-66f7-4fe4-9494-4802b078a30b /mnt/Backup01 btrfs defaults 0 1 

smb.conf

[global] workgroup = ESD dns proxy = no log file = /var/log/samba/log.%m max log size = 1000 syslog = 0 panic action = /usr/share/samba/panic-action %d server role = standalone server passdb backend = tdbsam obey pam restrictions = yes unix password sync = yes passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . pam password change = yes map to guest = bad user usershare allow guests = yes [homes] comment = Home Directories browseable = no read only = yes create mask = 0700 directory mask = 0700 valid users = %S [printers] comment = All Printers browseable = no path = /var/spool/samba printable = yes guest ok = no read only = yes create mask = 0700 [print$] comment = Printer Drivers path = /var/lib/samba/printers browseable = yes read only = yes guest ok = no [Backup01-Data01] path= /mnt/Backup01/Data01 browsable = yes read only false guest ok = no inherit acls = no inherit permissions = yes ea support = no store dos attributes = no printable = no #create mask = 0664 #force create mode 0664 #directory mask = 0775 #force directory mode = 0775 hide special files = yes follow symlinks = yes hide dot files = yes valid users = srvbackup invalid users = read list = srvbackup write list = srvbackup force user=srvbackup 

fstab on server (shortened)

//officebeere/Backup01-Data01 /mnt/Backup01-Data01 cifs _netdev,uid=1000,gid=1000,username=srvbackup,password=********** 0 0 

rsync command

sudo rsync -avit --no-p --progress --delete Zwergentrunk/ /mnt/Backup01-Data01/ 

Update:

I've tested more and i'can say it's not an btrfs issue (tested with an other HDD and ext4 still same problem) It's not only with rsync, tried with cp -a or cp -preserver=timestamps --> same issue but with a small difference on copy i'can see the correct modify date first and then it will be changed

I tried from Windows with copy and paste --> Modify date is correct

But with touch -r sourefile destfile, i get correct dates, so a workaround would be possible

I hope someone has a better Solution, i think it's a Samba Server or Mount smb share issue

Mount says that's are my Mount options

//officebeere/Backup01-Data01 on /mnt/Backup01-Data01 type cifs (rw,relatime,vers=3.1.1,cache=strict,username=srvbackup,uid=1000,noforceuid,gid=1000,noforcegid,addr=192.168.1.5,file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1,_netdev)