IOMeter on CIFS share

If you are trying to run IOMeter on network mounted drives, you might find that IOMeter disk targets doesn't show network drives. And most search results will tell you that IOMeter cannot be run on CIFS share

After playing with it for few hours, I found that older version of IOMeter (2006) does work with CIFS shares. Here is the download link - http://www.iometer.org/doc/downloads.html

1. Downloand IOMeter 2006 and install
2. Mount your network drive
3. Provide necessary permissions
4. Launch IOMeter after finishing Steps 2 and 3
5. Now you should see network drives in disk targets on IOMeter

Logrotate Windows files from Linux

I could not find a simple and free application to rotate log files on Windows. So, I used Linux to rotate log files on my Windows machine.

1. Configure the Windows Folder which has the log files, for sharing
2. Enable Read/Write Permissions
3. Mount the Windows Folder on Linux. Check out my post on how to Share Windows files with Linux - Share Windows Files with Linux

4. Now, create a file in /etc/logrotate.d to do the rotation. 
    In the below config, I am rotating the log files daily and saving the previous five copies

    root@localhost# more /etc/logrotate.d/winfiles
    /mnt/win/files.txt {
        daily
        rotate 5
        missingok
        compress
    }

Share Windows Files with Linux

- Install mount.cifs

        yum install cifs-utils -y

- Create a directory where you want the Windows folder 

root@localhost#mkdir /mnt/win

- Use mount.cifs  with the windows machine IP, folder and credentials to mount

root@localhost#sudo mount.cifs //10.4.23.67/Syslogs/ /mnt/win/ -o user=administrator,pass=password

root@localhost#
root@localhost#ls /mnt/win/
Documents Downloads
root@localhost#

ipv4: Neighbour table overflow

I was noticing the below error message in /var/log/messages. I also noticed that my linux DHCP server was not serving leases. Again, I modified the sysctl file to fix the issue.

Problem:

Jun 21 07:56:03 localhost kernel: [36050.926734] ipv4: Neighbour table overflow.

Jun 21 07:56:03 localhost kernel: [36050.930354] ipv4: Neighbour table overflow.

Jun 21 08:01:02 localhost kernel: [36349.592127] ipv4: Neighbour table overflow.

Solution:

1. Edit /etc/sysctl.conf

 vi /etc/sysctl.conf2. Change to have the following values

net.ipv4.neigh.default.gc_thresh1 = 8192

net.ipv4.neigh.default.gc_thresh2 = 16384

net.ipv4.neigh.default.gc_thresh3 = 16384

2. To load new changes type the following command:

  sysctl -p

What are these 3 parameters?

These parameters are defined in the Linux Kernel Code in /include/net/neighbour.h as integer, which suggests that maximal accepted value is (2^32 - 1)

gc_thresh1 - The minimum number of entries to keep in the ARP cache.

gc_thresh2 - The soft maximum number of entries to keep in the ARP cache. 

gc_thresh3 - The hard maximum number of entries to keep in the ARP cache.