"Tricks" to using VMware ESXi - what have you learned?

tankman1989

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I'm pretty new to ESXi but have used the VMware Player for a little longer and I have to say that both products are pretty amazing!

For those who don't know a lot about ESXi, it may seem totally proprietary and be it's own system but what I have found is that it is very similar to Linux in many ways, especially the CL, file structure and file system management. I'm a big supporter of how ESXi works for a number of reasons, especially with the advancement of multi-core processors and the growth in size of both mechanical and SSD drives. This makes creating an entire computer or copying one, as easy as moving a few files!

ESXi has built in features to copy to an from the machine and its "datastores" or what used to be called hard drives on servers. The built in features work but they leave a little to be desired on a few issues so I did some digging.

ESXi has a built in SSH server support so you can connect with PuTTy using the same credentials that you use with the VMware vSphere client. From this you can navigate the OS directories and look at the datastores and such. Standard Linux commands seems to apply here, some may not be installed though. By default, the SSH service is not enabled or started but it can be started manually or on boot. To access this open vSphere client and select the machine to which you want to connect in the left panel -> click on the "Configuration" tab -> under the "Software" topics select "Security Profile" -> click the "properties" (in blue lettering towards the top right) -> Select "SSH" and then click the "Options" button. Here you can choose to have it started on Host boot, or manually. Here's what it looks like:

esxiSSH.png


Once SSH is running you can use it as any other machine running SSH! If you want to copy/clone a VM you can do it very easily using standard Linux commands which some might find easier than using the VMware GUI.

File Transfer Programs other than built in ones. I don't like the built in up/download features for the datastores so I choose to use WinSCP which will resume broken downloads and show speeds and such, a few things the built in options don't have. You just connect to it using the IP address listed for the host, navigate to the datastore: /vmfs/volume and within this is the various datastores that you created. The default name is "datastore". You can upload and download to this location.

So have you found any other interesting tricks that you want to share with us?
 
It is all the other features that make ESXi appealing.

Take for example, High Availability, which if a server crashes WILL reboot any guest OS on a different physical host...

Then there is vMotion, which allows you to drag and drop a Guest OS/Server from one Physical ESXi Server to another in the same shared pool. When doing this, it will NOT break any TCP sessions... Sure several IP packets get dropped, BUT you will NOT loose any TCP Segments; since, the CRC will cause a resend if needed. The latency will get high, but the connections won't drop. Therefore, file transfers in progress are not interrupted, downloads from websites are fine, open SQL handles work, etc! UDP protocols loose a couple packets here and there, but typically those services are okay with that. i.e. Stream a video and drop a small handful of UDP segments, but this typically goes unoticed. Maybe a couple pixels (out of millions) are the wrong color in a couple frames at 30/sec... Your eye won't notice. I can take every server in the blade chassis down for a BIOS update and reboot ESXi without disrupting any services!

sVmotion allows me to move the Shared Storage to different LUNs presented to VMWare. I can, for example replace my entire SAN at work without any downtime to ANY applications.

Fault Tolerance allows a VM to run simultaneously on two physical hosts at exactly the same time. It is like a never-completing vMotion that is 99.999% ready to go. The moment the Fault-Tolerate guest encounters a problem (i.e. Physical server gets struck by a power surge or looses power) the process completes and the guest OS is now hosted on a different Physical Host. Like a VMotion, you get a tiny bit of latency that's it.

It will NOT even drop ICMP pings!
 
Yup...flexibility and uptime, features such as vMotion...is where you really start to see the benefits of VMWare for larger business clients.

Get a pair of nice servers....have them share a high grade SAN, split your guests between the 2 hosts. But east host has enough "nut" to run all the guests at once if it needs to.
 
It is all the other features that make ESXi appealing.

Take for example, High Availability, which if a server crashes WILL reboot any guest OS on a different physical host...

Then there is vMotion, which allows you to drag and drop a Guest OS/Server from one Physical ESXi Server to another in the same shared pool. When doing this, it will NOT break any TCP sessions... Sure several IP packets get dropped, BUT you will NOT loose any TCP Segments; since, the CRC will cause a resend if needed. The latency will get high, but the connections won't drop. Therefore, file transfers in progress are not interrupted, downloads from websites are fine, open SQL handles work, etc! UDP protocols loose a couple packets here and there, but typically those services are okay with that. i.e. Stream a video and drop a small handful of UDP segments, but this typically goes unoticed. Maybe a couple pixels (out of millions) are the wrong color in a couple frames at 30/sec... Your eye won't notice. I can take every server in the blade chassis down for a BIOS update and reboot ESXi without disrupting any services!

sVmotion allows me to move the Shared Storage to different LUNs presented to VMWare. I can, for example replace my entire SAN at work without any downtime to ANY applications.

Fault Tolerance allows a VM to run simultaneously on two physical hosts at exactly the same time. It is like a never-completing vMotion that is 99.999% ready to go. The moment the Fault-Tolerate guest encounters a problem (i.e. Physical server gets struck by a power surge or looses power) the process completes and the guest OS is now hosted on a different Physical Host. Like a VMotion, you get a tiny bit of latency that's it.

It will NOT even drop ICMP pings!

You say these things as if they are impressive:D

I really wish I had gotten my foot in the door with Vmware back in 06-07 when I had a decent chance. I liked their technology but they were a little "unproven" at the time in their virtualization. Well, at least I can pick a winner.

I'd like to be able to set up servers how you described above so I can learn how to admin VMware. Does this only work on identical servers? That is no problem for me, just curious.
 
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