CIFS from Linux = periodic writes to system dataset

[sky67]

Hello,

I have following problem with latest stable FreeNAS 9.3. There is relatively a lot of writes to system dataset. I disabled write syslog and rrd data to it and still geting around 0.5 MB writes cca every minute. So I cannot have it on storage pool because the drives will never go to sleep and it is problematic to have it on another flash drive - it is around 0.5 GB writes daily. (The reporting shows something like 1 GB writes daily.)

The iostat and zpool iostat see the I/O, but no file on /var/db/system is modified / changed and top -m io -o write does not see it.

I traced it to mounted CIFS share from Linux 3.14. The connection gets disconnected and reconnected every minute by FreeNAS (FreeNAS sends TCP F packet first), which apparently causes write to system dataset. I think the write can be related to interprocess communication between parent and child smbd process, but I am not able to confirm that with truss or ktrace.

What is exact cause of these writes to system dataset (what is saved) and is it possible to disable it? Is it possible to prevent disconnection every minute when CIFS share is mounted from Linux?

Thanks.

 

[SweetAndLow]

I use cifs mounts on Linux and haven't noticed any disconnects. Sometimes I can get smbd to core but that is probably unrelated. Are the disconnect happening because smbd is crashing?

 

[sky67]

I use cifs mounts on Linux and haven't noticed any disconnects. Sometimes I can get smbd to core but that is probably unrelated. Are the disconnect happening because smbd is crashing?

They are disconnects of TCP connections, mount on the Linux works fine for the user. (Did you check with tcpdump or netstat, that mount is still holding the same TCP connection?) I see no sign of crash, how can I detect it for sure on FreeNAS 9.3?