ReadyNas 102 slow since 6.5.0 update

Hi

I have an RN104 with 4 disk

After i updated to 6.5.X i got terrible system performance :(

I can't download the logs ... timeout, sometimes i can't connect to the readygear frontend, because can't connect to readynasd ...

The disk speed sometime 160Mb/s sometime 286kb/s! (YES! 286kb/sec) ... 

I tried the btrfs scrub, but readynasd crashd and btrfs defuncted ... (i canceld the scrub from terminal)

i can't connect with samba, can't connect with nfs ...

the ssh terminal sometime freez, wait disk IO ... 

I removed some data from the server, but i think it's not too optimized, when i need 600GB free space for normal performance .... that is a joke

root@NyulNAS:/etc# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
10240+0 records in
10240+0 records out
83886080 bytes (84 MB) copied, 0.565592 s, 148 MB/s
root@NyulNAS:/etc# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
10240+0 records in
10240+0 records out
83886080 bytes (84 MB) copied, 0.516513 s, 162 MB/s
root@NyulNAS:/etc# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
10240+0 records in
10240+0 records out
83886080 bytes (84 MB) copied, 0.519188 s, 162 MB/s
root@NyulNAS:/etc# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
10240+0 records in
10240+0 records out
83886080 bytes (84 MB) copied, 0.504469 s, 166 MB/s
root@NyulNAS:/etc# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
10240+0 records in
10240+0 records out
83886080 bytes (84 MB) copied, 0.510758 s, 164 MB/s
root@NyulNAS:/etc# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
10240+0 records in
10240+0 records out
83886080 bytes (84 MB) copied, 0.507346 s, 165 MB/s

root@NyulNAS:~# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
^C2298+0 records in
2298+0 records out
18825216 bytes (19 MB) copied, 6.44448 s, 2.9 MB/s

root@NyulNAS:/etc# dd if=/dev/zero of=/Data/t.bin bs=8k count=10k
^C^C^C^C

1+0 records in
1+0 records out
8192 bytes (8.2 kB) copied, 450.47 s, 0.0 kB/s

0.0kb/s ... :)