a file I/O error has occurred while accessing vmware converter

While converting physical Windows 7 machine to Virtual machine of infrastructure type, I got this error. The error seems it is unable to read/write source or destination datastore.

I have installed VMware-converter-en-6.2.0-8466193 on Windows 7 physical machine with option locally selected. (not at server/client option)

All of my ESXi servers are connected to the vCenter Server, so I had to use vCenter Server's IP address to send this physical machine to the virtual world.

The issue i found was with the dns resolution to the vCenter Server's hostname. Since I am not using the same dns server on the Windows 7 client machine. So I updated the host entries manually for the vCenter Server's hosname to it IP address.

After adding dns eteries to the hostfile of windows 7, I am not getting this "a file I/O error has occurred while accessing vmware converter" and the migration has started. 

How to check Gray-log current running version

If you planning to upgrade your graylog and want to see what your graylog current version is, here is how you can check it.
  • Go to the Graylog Web Interface
  • Click on System/Nodes
  • Under System/Nodes --- Click on the Nodes 
  • Scroll down to the 'System'
Here you can see the current version of your graylog server

Graylog is restarting stuck with disk full

Graylog is restarting...
There is no Graylog web application running at the moment, please reload this page in a minute. It can take up to 1-2 minutes until all services are running properly. In case this is a permanent error, check the following:

Check if all services are running - sudo graylog-ctl status shows an overview of all running services
Check for errors in log files - Relevant services write log files here: /var/log/graylog/*/current
Ask for help - If there is no way to fix the issue ask for help:

I got this error on my Gray-log server, upon troubleshooting I found that the disk was 100% full and was unable to start elastic search mongodb and etcd while checking gray-log server status with command
#graylog-ctl status

Solution to this problem was obvious that I have to clean some disk space to get gray-log working again but what file should I delete was my next thought!

Upon googling I found that I could safely delete the old log files of elastic search to free up the space.

So I stopped gray-log server with

$sudo graylog-ctl stop

My gray-log installation path for elasticsearch logs was at


Listed the files at this path

root@graylog:/var/opt/graylog/data/elasticsearch/graylog/nodes/0/indices# ls -al

drwx------ 7 graylog graylog 4096 Aug 12  2016 graylog_0
drwx------ 7 graylog graylog 4096 Aug  3  2017 graylog_1

I deleted one old log folder "graylog_0" which had consumed disk space of around 5 GB inside it.

root@graylog:/var/opt/graylog/data/elasticsearch/graylog/nodes/0/indices# rm -R graylog_0/

After deleting the log folder I restarted the graylog server

root@graylog:~# graylog-ctl start

Now I can access graylog server, all my configuration and dashboards are in place and working good. But I am getting an error for etcd (for clustering of node) of database corruption, a type of file "wal" is not accessible.

Since this is the only of my node and not a cluster configuration, I deleted the etcd folder and reconfigured the graylog server.

Delete the etcd folder here

root@graylog:~#/var/opt/graylog/data/rm -R etcd

root@graylog:~#/var/opt/graylog/data/graylog-ctl reconfigure

Now i can see the working status of all service with graylog as below

root@graylog:/var/opt/graylog/data/etcd/member# graylog-ctl status
run: elasticsearch: (pid 4437) 21s; run: log: (pid 876) 1059s
run: etcd: (pid 4272) 25s; run: log: (pid 891) 1059s
run: graylog-server: (pid 4490) 20s; run: log: (pid 857) 1059s
run: mongodb: (pid 4314) 23s; run: log: (pid 890) 1059s
run: nginx: (pid 4515) 20s; run: log: (pid 856) 1059s

How to import Putty Saved Connections to mRemoteNG

Just started using mRemoteNG and its being very cool to connect to different remote connection with different protocols e.g Window Remote Desktop, VNC to Linux, SSH, HTTP connection etc. from a single application.

As new user I configured some remote desktop connection which was quite easy to figure out. But when I wanted to add SSH connections, it came in my mind to import all of the saved connections in the putty. But I couldn't figure it out how can it be done, though it was quite easy and here are the steps.

  • Open your mRemoteNG
  • Create a folder if you want segregation of multiple networks
  • Create a new connection
  • Enter the IP address of remote server under connection in Config pane
  • Under the config pane, select protocol "SSH version 2". 
Once you select protocol to SSH version 2 you are given option to import putty sessions, as shown in the snap below.

In the above snap, I have imported CSR-AWS session from my saved sessions in Putty.

VMWare Datastore inactive but Status Normal

I got this issue with my iSCSI disk provided by Microsoft Windows Server. I am able to access the iSCSI datastore, all of my Virtual Machines are operational with any issue, my iSCSI datastore is showing as inactive but its status is showing normal.
It happend after I had removed iSCSI targets from Windows but and added new target after some time.
What I did;
  • Rescanned all datastore multiple times --- no luck
  • restarted management services from SSH of all ESXi hosts with command 
  • $ services.sh restart --- no luck
  • Removed and re-added targets from iSCSI (Windows) Side --- no luck
  • Removed few VMs which were in inaccessible state and then rescanned datastore --- no luck
Finally restarted each ESXi host at a time, it solved the problem.

Connection control operation failed for disk 'ide1:0'

I was getting this error while removing Operating System ISO image mounted on the Virtual Machine.

What worked for me, is
1. Uncheck the "Connected and Connect at power on" from Device Status.
2. Then Change the Device type from "Datastore ISO File to Client Device" Radio Button
3. and press OK to save the changes.

Note:- I was able to remove the mounted ISO only by directly logging to the ESXi at https://esxi-ip-address/ui

where it asks

"The guest operating system has locked the CD-ROM door and is probably using the CD-ROM, which can prevent the guest from recognizing media changes. If possible, eject the CD-ROM from inside the guest before disconnecting. Disconnect anyway and override the lock?"

You need to select yes to eject the CD-ROM and then remove the ISO file successfully.

snmpwalk End of MIB

[root@monitoring ~]#  snmpwalk -c public -v1
End of MIB

I was trying to do snmwalk walk for a Cisco Router in GNS3, and was getting only End of MIB after a snmpwalk command. 
It turned out that in my Cisco Router configurations I had allowed my SNMP host with ip address with community string "public" but I had not configured the community string separatly with the command 
#snmp-server community public

This was my configuration mistake but took some time to figure it out

GNS3 Docker Error while creating node: Docker has returned an error: Cannot connect to host docker:80

Error while creating node: Docker has returned an error: Cannot connect to host docker:80 ssl:False [No such file or directory]

After adding docker template for Alpine Linux in gns3, you get above mentioned message when you want to use alpine linux in GNS3.

To get rid of this message you have to install Docker by following below link
curl -fsSL https://get.docker.com/ | sh

If you do not have curl installed then instal curl first with below command.
apt-get install curl

After installing Docker you need to add your user name in the docker group with the following command. 
$ sudo usermod -aG docker your_username

Verify if the docker service is started with following command
$ service docker status

If docker is not started then start with following command 
$ sudo service docker start

Logout from GNS3 Virtual Machines and log back. Start gns3 and use alpine linux.

Advantage of using System ID extension in Switch Bridge ID

The format of the original 802.1d bridge ID was redefined from two byte priority + MAC address to System ID extension mainly due to the advent of multiple spanning trees as supported by Per VLAN Spanning Tree Plus (PVST+) and IEEE 802.1s Multiple Spanning Trees (MST). With the old-style bridge ID format, a switch’s bridge ID for each STP instance (possibly one per VLAN) was identical if the switch used a single MAC address when building the bridge ID. Having multiple STP instances with the same bridge ID was confusing, so vendors such as Cisco Systems used a different Ethernet BIA for each VLAN when creating the old-style bridge IDs. This provided a different bridge ID per VLAN, but it consumed a large number of reserved BIAs in each switch. 

The System ID Extension allows a network to use multiple instances of STP, even one per VLAN,  but without the need to consume a separate BIA on each switch for each STP instance. The System ID Extension field allows the VLAN ID to be placed into what was formerly the last 12 bits of the Priority field. A switch can use a single MAC address to build bridge IDs, and with the VLAN number in the System ID Extension field still have a unique bridge ID in each VLAN. The use of the System ID Extension field is also called MAC address reduction, because of the need for many fewer reserved MAC addresses on each switch.

How to configure Default Gateway on Nexus 1000v

In case you are finding it hard to reach default gateway from your newly installed Nexus 1000v virtual machine, here is one quick thing to check and configure before you can reach to the default gateway and other allowed subnets from your Nexus 1000v VM.

Configure the management IP Address and default gateway on Nexus 1000v as per below commands

conf t
interface mgmt 0
ip address
vrf context management
ip route
copy run start

Note: Change the IP address as per your subnet.

Why STP Bridge Priority is Configured in increment of 4096

Spanning-tree operation requires that each switch have a unique BID (Bridge ID). In the original 802.1D standard, the BID was composed of the bridge priority and the MAC address of the switch, and all VLANs were represented by a CST, Common Spanning Tree. Because Cisco started to use unique instance in PVST+ PVRST+ for each VLAN STP Process, there came need to provide Unique BID for each separate instance of STP per VLAN. So what Cisco Did! divided the Bridge priority field of 16 bits into two parts, 4 bits for priority and 12 bits for VLAN ID and named it as Extended VLAN ID. Now because only left most four bits are reserved for Bridge priority, you can only make the combinations of discrete values in increments of 4096 with those bits.