ESXi gets disconnected from vCenter server intermittantly

 Issue:

ESXi gets disconnected from vCenter server intermittantly

Solution:

This issue occurs when the UDP heartbeat message sent by ESX/ESXi host is not received by vCenter Server.

1. Select the vCenter object from the inventory under Hosts and Clusters.
2. Select the Manage or Configure tab.
3. Select Settings > Advanced Settings.
4. Click Edit. and add new value
5. In the Key field, type:
   
   config.vpxd.heartbeat.notRespondingTimeout
    
6. In the Value field, type:
   
   120
    
7. Click Add.
8. Click OK.

     9.SSH to vCenter with root credentails and restart below service:

 [ ~ ]# service-control --stop vmware-vpxd; service-control --start vmware-vpxd

Operation not cancellable. Please wait for it to finish...

Performing stop operation on service vpxd...

Successfully stopped service vpxd

Operation not cancellable. Please wait for it to finish...

Performing start operation on service vpxd...

Successfully started service vpxd

resized volume size not detecting VMware existing datastore

 Issue:

resized backend volume size from storage array. but the VMware ESXi datastore size not getting increased after "refresh capacity" also. Tried storage iscsi adapter rescan/refresh as well,

Solution:

  Go to Existing datastore ->Configure find out the Lun ID of the existing datastore (can be found from Storage array where you provided LUN id)

 right click on the Datastore and choose "Increase capacity" option, in the next wind select the existing LUN ID and complete the steps.

Now you will see the new Datastore size.

iperf3 to measure network bandwidth between linux servers

 1.Install iperf3 on both server and client:

    download:  https://iperf.fr/iperf-download.php#fedora

    Install with: rpm -ivh iperf3-3.1.3-1.fc24.x86_64.rpm

2.Run server to listen on port 5201 with below command:

   iperf3 -s -f K

Example:

 /]# iperf3 -s -f K

-----------------------------------------------------------

Server listening on 5201

-----------------------------------------------------------

Accepted connection from 10.10.10.1, port 44246

[  5] local 10.10.1.1 port 5201 connected to 10.10.10.1 port 44248

[ ID] Interval           Transfer     Bandwidth

[  5]   0.00-1.00   sec  3.01 GBytes  3157621 KBytes/sec

[  5]   1.00-2.00   sec  4.20 GBytes  4399773 KBytes/sec

[  5]   2.00-3.00   sec  2.20 GBytes  2305199 KBytes/sec

[  5]   3.00-4.00   sec  2.08 GBytes  2184224 KBytes/sec

[  5]   4.00-5.00   sec  2.65 GBytes  2775254 KBytes/sec

[  5]   5.00-6.00   sec  2.95 GBytes  3095611 KBytes/sec

[  5]   6.00-7.00   sec  2.81 GBytes  2942424 KBytes/sec

[  5]   7.00-8.00   sec  2.82 GBytes  2951992 KBytes/sec

[  5]   8.00-9.00   sec  3.64 GBytes  3815794 KBytes/sec

[  5]   9.00-10.00  sec  2.41 GBytes  2527937 KBytes/sec

[  5]  10.00-10.04  sec  76.0 MBytes  2078139 KBytes/sec

- - - - - - - - - - - - - - - - - - - - - - - - -

[ ID] Interval           Transfer     Bandwidth

[  5]   0.00-10.04  sec  0.00 Bytes  0.00 KBytes/sec                  sender

[  5]   0.00-10.04  sec  28.8 GBytes  3012197 KBytes/sec                  receiver

-----------------------------------------------------------

Server listening on 5201

3.For client run below command:

   ~]# iperf3 -c 10.10.10.2 -f K

Connecting to host 172.17.38.42, port 5201

[  4] local 10.10.10.2 port 44248 connected to 10.10.10.1 port 5201

[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd

[  4]   0.00-1.00   sec  3.17 GBytes  3320810 KBytes/sec    0   1.56 MBytes

[  4]   1.00-2.00   sec  4.12 GBytes  4317820 KBytes/sec    0   1.87 MBytes

[  4]   2.00-3.00   sec  2.21 GBytes  2319258 KBytes/sec    0   1.87 MBytes

[  4]   3.00-4.00   sec  2.06 GBytes  2160896 KBytes/sec    0   1.87 MBytes

[  4]   4.00-5.00   sec  2.70 GBytes  2835078 KBytes/sec    2   1.44 MBytes

[  4]   5.00-6.00   sec  2.92 GBytes  3065520 KBytes/sec    0   1.69 MBytes

[  4]   6.00-7.00   sec  2.80 GBytes  2937884 KBytes/sec    0   1.75 MBytes

[  4]   7.00-8.00   sec  2.85 GBytes  2989876 KBytes/sec    0   1.81 MBytes

[  4]   8.00-9.00   sec  3.61 GBytes  3788754 KBytes/sec    0   1.87 MBytes

[  4]   9.00-10.00  sec  2.38 GBytes  2497104 KBytes/sec    0   1.94 MBytes

- - - - - - - - - - - - - - - - - - - - - - - - -

[ ID] Interval           Transfer     Bandwidth       Retr

[  4]   0.00-10.00  sec  28.8 GBytes  3023283 KBytes/sec    2             sender

[  4]   0.00-10.00  sec  28.8 GBytes  3023283 KBytes/sec                  receiver

 

Linux create random data file easily

 

run below command to generate a random data content file in linux:

For 1GB file:

head -c 1G </dev/urandom >myfile

For 1MB file:
head -c 1M </dev/urandom >myfile