On Nov 7, 2011, VMware published this kb article about iSCSI delays:
ESXi 5.x boot delays when configured for Software iSCSI
it includes a link to this site:
VMware ESXi 5.0, Patch Release ESXi500-201111001
which tells you about the ESXi500-201111001.zip file you download from here:
by searching for the filename, or even easier, here's the direct download link for ESXi500-201111001.zip. This zip file contains numerous patches in the form of VIB files, the screenshot below shows the actual work it did in my situation, which is not much. But consider this a rehearsal for ESX 5.1 or whatever the next release is called, which may use a similar procedure. Also, be sure to shut down all VMs first, since this will require your host be rebooted!
Alternatively, if you must be extremely cautious in a production environment here, and don't necessarily have the usual vSphere Client GUI view of your environment, you might also consider these more advanced set of instructions (that take much longer to get through, but have the same end result).
Here's a simple/fast approach I used in a lab box (with no running VMs), it took 10 minutes total, and there was no issue with any of my virtual machines running after the update.
It’s quite easy with the ESXi vSphere client, step-by-step found here. You can do this for each time you boot, not leaving it enabled at start time (security consideration).
I happened to use freeware WinSCP (or Veeam FastSCP) and the simple GUI, but using Linux will do nicely too. Point WinSCP to your ESX host IP, drag and drop the file you downloaded:
into the ESXi 5.0 hosts datastore, I used /vmfs/volumes/1.5TB
Then, at PuTTY (SSH for Windows) session on the ESXi 5.0 host
Enter the following 2 commands (substituing your volume name, where I have
1.5TB in example below):
esxcli software vib update --depot=/vmfs/volumes/1.5TB/ESXi500-201111001.zip
It may take several minutes to return the cursor to you, at which point, it should say something like this:
That's all! At boot time, you'll see build 504890 shown on the screen.