Configuring Your Network to Enable Jumbo Frames › How to Exploit Jumbo Frames for CA Cloud Storage for System z › Update the CA Cloud Storage for System z Linux Server Configuration Files

Update the CA Cloud Storage for System z Linux Server Configuration Files

To ensure that your system can handle jumbo frames, update your CA Cloud Storage for System z Linux Server configuration files.

Follow these steps:

1. Use a telnet session to log in to Linux on System z.
2. Run the following command to become a super user:

   su
   

3. Enter your root password:

   root password:
   

4. Enter the following command in the file system table:

   vim /etc/fstab
   

5. Modify your NFS device line entries to include the retrans and timeo key value pairs, like the following example:

   141.202.201.27:/rfs/qa1 /var/lib/cacloud/vault_01/mp_01 nfs 
   rsize=131072,tcp,nolock,wsize=131072,nfsvers=3,intr,bg,retrans=2,timeo=5 0 0
   

6. Enter the following command to modify your sysctl configuration file:

   vim /etc/sysctl.conf
   

7. Add the following statements to the end of the file:

   ## IPV4 specific settings
   # turn TCP timestamp support off, default 1, reduces CPU use
   net.ipv4.tcp_timestamps = 0
   # turn SACK support off, default on
   # on systems with a VERY fast bus -> memory interface this is the big gainer
   net.ipv4.tcp_sack = 0
   # set min/default/max TCP read buffer, default 4096 87380 174760
   net.ipv4.tcp_rmem = 10000000 10000000 10000000
   # set min/pressure/max TCP write buffer, default 4096 16384 131072
   net.ipv4.tcp_wmem = 10000000 10000000 10000000
   # set min/pressure/max TCP buffer space, default 31744 32256 32768
   net.ipv4.tcp_mem = 10000000 10000000 10000000
   ### CORE settings (mostly for socket and UDP effect)
   # set maximum receive socket buffer size, default 131071
   net.core.rmem_max = 524287
   # set maximum send socket buffer size, default 131071
   net.core.wmem_max = 524287
   # set default receive socket buffer size, default 65535
   net.core.rmem_default = 524287
   # set default send socket buffer size, default 65535
   net.core.wmem_default = 524287
   # set maximum amount of option memory buffers, default 10240
   net.core.optmem_max = 524287
   # set number of unprocessed input packets before kernel starts dropping them; default 300
   net.core.netdev_max_backlog = 300000
   

8. Enter the following commands to modify your rules.d device file:

   vim /etc/udev/rules.d/51-qeth-0.0.nnnn.rules (where nnnn is the OSA device address)
   

9. Add the following statements before the online attribute statement:

   ACTION=="add", SUBSYSTEM=="ccwgroup", KERNEL=="0.0.0a60", ATTR{blkt/inter}="5"
   ACTION=="add", SUBSYSTEM=="ccwgroup", KERNEL=="0.0.0a60", ATTR{blkt/inter_jumbo}="15"
   ACTION=="add", SUBSYSTEM=="ccwgroup", KERNEL=="0.0.0a60", ATTR{blkt/total}="250"
   ACTION=="add", SUBSYSTEM=="ccwgroup", KERNEL=="0.0.0a60", ATTR{buffer_count}="128"