Archive for November, 2017

VMware ESXi and iSCSI storage issue.

I was having some trouble with a couple iSCSI volumes in a two member ESXi cluster. Two of the volumes were display in the client adapater details as mounted, but the volumes were not showing as mounted in the Storage pane or with a df command in the CLI.

Logs to check in for a possible hint:

# grep -i volumename vobd.log
# grep -i volumename vmkernel.log

When I listed the filesystems from the CLI using the following, the volumes were not listed or obviously mounted:

# esxcli storage filesystem list

List iSCSI adapters configured:

# esxcli iscsi adapter list

A rescan of all the adapters did not work either:
Rescan adapter:

# esxcli storage core adapter rescan -a

To list all the devices and their world IDs:

# esxcli storage core device world list

To only list the world IDs tied to one device:
# esxcli storage core device world list -d mydeviceid

List all guests and their World ID:

# esxcli vm process list

Restart management services:

# restart

The vmkernel.log had a clue. A message stating that “Device mydeviceid detected to be a snapshot:”

# grep -i mydeviceid vmkernel.log

Listing the snapshots revealed the issue:
List snapshot:

# esxcli storage vmfs snapshot list

Both of my troubled volumes were listed as snapshots. I was told by VMware that this can happen if something changes in the META data of the iSCSI SAN/NAS. This was possible in my case, because I just updated my FreeNAS to the latest version. All that needed to be done was remove the snapshots. Once removed the volumes were mounted immediately.
Remove snapshot:

# esxcli storage vmfs snapshot mount -u “59b153b3-86f464ec-999d-a0d3c1f0cdf0”
# esxcli storage vmfs snapshot mount -u “59b1a680-bc18c507-831a-2c768a56eb24”

User Specific ssh/sftp/scp Customizations in CentOS.

I ran into a situation where I was trying to place files for support, and they only supported 3des ciphers (3des-cbc,blowfish-cbc,3des-cbc). The global ssh client configuration on my system only supported aes ciphers. Instead of adding the 3des to the global configuration (/etc/ssh/ssh_config), I wanted to add it to just one account.

$ vi ~/.ssh/config
Ciphers aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,3des-cbc

$ chmod 400 ~/.ssh/config

Then, I could run ssh/sftp/scp with -vvv to verify. You should see the following output:

debug2: ciphers ctos: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,3des-cbc
debug2: ciphers stoc: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,3des-cbc

Of course, you can add any customization you want to the ~/.ssh/config file you want. This is just an example. What got me was the global config file is call ssh_config, while the user config file is called config. man ssh_config help me discover the correct name. If you do not have the correct name, you need to pass a -F myspecialcustomconfigfile to the ssh/sftp/scp command.

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