Samba causing system slow down

[mlblandf]

Hello,

I am currently running Fedora 14 on an x86_64 system that acts as a whole house server for named, dhcp, nfs, nis, htpp, samba, etc

My issue has existed for a few years and I am just now getting around to posting about it.

I have a simple samba configuration for sharing files to a windows VM on another box.

Here is the config:

[global]

workgroup = NERD
server string = Samba Server on NERD
security = user
hosts allow =192.168.1.
log file = /var/log/samba/%m.log
max log size = 50

passdb backend = smbpasswd

dns proxy = no

[homes]
comment = Home Directories
browseable = no
writable = yes


This seems to work well for extended periods of time without issues until I transfer some large files like DVD ISOs from the client to the server, or the server to the client. Once a large file has been transferred, then all remote access becomes painfully slow. NFS access, samba access, even ssh'ing into the server becomes painfully slow.

Rebooting the server clears up the issue.

Any suggestions on what might be wrong and/or how to go about debugging this issue?

Michael

[Doug G]

Are there any clues in the samba log files?

[mlblandf]

Sorry for the delayed response. It was a few days before I was able to look at this again.

As my test, I added 5 movies to Itunes where the files live on the Linux machine running samba.

Then I sync'ed those movies to the ipad.

Now, the file server is completely sluggish.

I looked at the logs from the samba server. There are no entries or errors from today when I did the sync. The only messages are from when the client connected to the samba server yesterday.

Looking at top, there is still more than a gig of free memory and no swap being used.

dmesg doesn't show any errors or messages since boot.

/var/log/messages only show the typical DNS/DHCP messages from those services, but nothing of interest from samba.

I am stumped.

I will reboot the server now so the environment becomes useful again.

I welcome any thoughts.

Michael

[beaker_]

How about:

https://wiki.samba.org/index.php?tit...rch=slow&go=Go
http://www.samba.org/samba/docs/man/...html#id2691160

[jpollard]

Just out of curiosity, try restarting samba just to see if that has any effect.

If it does, then I would suspect the speed problem may be related to locking issues (directory level).

Does "top" show any heavy hitters? (I doubt it, as I suspect the system itself is fine, but a lock on a directory can hang things).

[mlblandf]

Thanks for both of your responses.

The slowness isn't with the performance of samba. The files transfer at a normal rate until the slowness begins. Then the slowness impacts the entire system - not just samba. NFS, ssh, etc are all slow.

Restarting samba doesn't have any effect in resolving the issue.

Top doesn't show anything either. The server is sitting there idle with no processes eating more than 2-3% of a quad core cpu.

[beaker_]

Then you need to take your time and observe. The common denominators I see are; the nic, the filesystem, and the network. Assuming you've already done a top so you know there's nothing consuming resources then think about how to:

1. Replace the nic with a known, good, trustworty nic.
2. Test or beat the harddrive to death so you know it's not trying to read/write to bad sectors.
3. Push or find your networks limits with two known to be good machines or services. Might discover a flaky chord, switch, or router (?).

A guess. If it's running headless, then besure you're booting into runlevel 3 as I've seen X grabbing 90% cpu before (couldn't detect monitor) but that was some time ago.

[mlblandf]

Hello,

I have been watching this issue for months. Every time I start looking into the issue I come up empty handed. That is why I started posting.

I spent the morning trying to replicate the issue without samba and have not been able to.

From a known working client 'A' I have used cp+nfs to transfer all of the contents of the file server to /dev/null in a loop for several hours. This transfers several TB of data quickly without issues. Server and client remain responsive. There are no errors in netstat, nothing in dmesg, etc.

From the server itself I also did a cat /dev/sda<part> /dev/null in a loop several times. This responds quickly without issue.

The known host 'A' also is the host for the VM 'B' that running windows and connecting to the server. Since we have already ruled out the network card in this machine and the network itself, the only thing left is some strange interaction with samba.

The server, clients, and the network remain stable until I try to use a windows client to transfer large amount of data from the server and then the server becomes very sluggish. Once it becomes sluggish, it doesn't recover without a reboot.

I am at a loss here.

[mlblandf]

Just an update to this issue.

I updated to Fedora 16 and the problem is resolved. I am not sure if the new kernel or the 3.6 version of samba but the problem is definitely gonie.