I noticed a couple of people reported this problem in the last two months so I figured a blog post would be useful. This thread on VMTN triggered this article. If your ESXi host is disconnected from vCenter (even 5.0 and 5.1 appear to be impacted by this) and you see error messages in your log files about free space like these:

WARNING: VisorFSObj: xxxx: Cannot create file /var/spool/snmp/xxxxxxxx_x_
x_xxxx.trp for process hostd-worker because the inode table of its ramdisk (root) is full.

VmkCtl Locking (/etc/vmware/esx.conf) : Unable to create or open a LOCK file. Failed with reason: No space left on device

This could be caused by the fact that ESXi is running out of inodes. You can simply check that on the command line by using the following command:

stat -f /

The outcome of this command will look as follows:

File: “/”
ID: 1        Namelen: 127     Type: visorfs
Block size: 4096
Blocks: Total: 449852     Free: 324368     Available: 324368
Inodes: Total: 8192       Free: 55

As you can see the amount of “free” inodes is low and this is causing the experienced issues. In some cases it is reported (by vdsyn in this case) that “/var/spool/snmp/” is full and needs to be cleaned out. In this KB Article “/var/run/sfcb/” is explicitly called out and also explains what you can delete and how. So make sure to look at those two directories when an ESXi host is disconnected from vCenter.