6.4.1 Update Unusable

I have gone back and forth with 6.4.0 and 6.4.1 on ReadyNAS 104 (4x2TB WD+Seagate HDDs), and here is the net of my experience: 

# 6.4.0

   + Response time for Samba connections (Windows Explorer) is very good, no issues.

    - Is unable to work well with backup to an external USB hard-disk, the NAS just freezes and needs to be restarted by unplugging the power. 

# 6.4.1 or 6.4.2 T59 beta

   + Is able to handle backups to attached USB devices, no issues

   - Response to Samba connection is good initially, but gets slower quickly and soon the NAS just freezes when connected from Windows Explorer

When I went back the first time from 6.4.1 to 6.4.0, the NAS switched Disk-4 to Recovery mode, and it took 4 days to recover, and the response for everything was sluggish. So I was very nervous about losing data or going through the agony of another recovery cycle, but just for the sake of confirming it, (and since I managed a full backup to a USB HDD), I switched about 4 times (twice for each version). The issues I mentioned above was consistent. I tried the 6.4.2 beta with the link given in this thread, but the behaviour was similar to that of 6.4.1 for me, made no difference. 

Overall, I would suggest that folks wait for another version to come out, as 6.4.1 really makes the NAS unsuable. Backup is very important, but still is secondary to availability of the device itself. I have switched back to 6.4.0 for now.