When is an Operating System "not" an Operating System?

[Guardian1234]

Since I'm new to the vSphere 5, perhaps someone can enlighten me. The answers will pretty much determine whether or not my IT dept makes the decision to move towards generic PC virtualization w/VMWare or stick with the various "NIX platform's form of virtualization techniques, IE Solaris Zones, AIX Micro Partitioning, etc.

Q1: Is the ESXi-v5 Hypervisor considered an OS? Or is it a bare-metal application that presents/manages a given VM to a guest OS.

Q2: Once booted, is the env that I log into (as root) via TSM, SSH, etc persistent or non-persistent, IE: if I make changes to files such as owner/group/mode, will they persist from reboot to reboot or just simply disappear/reset on the next boot cycle?

From what I've read, it appears that some file changes (internal to the file such as text/configuration changes) will persist, even though it appears that the ESXi-v5 server is running 100% from memory. For example syslog.conf? But if I change the mode, owner etc will that also persist. At this point whether or not it breaks something to do so is not as important as the topic of persistence (at least that's what my management is concerned about).

Anybody?  A response (not just a read) would really be appreciated.

Thx.

[Troy_Clavell]

Q1: Is the ESXi-v5 Hypervisor considered an OS? Or is it a bare-metal  application that presents/manages a given VM to a guest OS.

Yes, ESXi is an OS and a bare metal install

Q2: Once  booted, is the env that I log into (as root) via TSM, SSH, etc  persistent or non-persistent, IE: if I make changes to files such as  owner/group/mode, will they persist from reboot to reboot or just simply  disappear/reset on the next boot cycle?

this question can be a yes for both.  A good article below may help

http://www.virtuallyghetto.com/2011/08/how-to-persist-configuration-changes-in.html

[mcowger]

1) ANYTHING that mediates access to physical hardware is an operating system. Hence, a hypervisor like ESXi certainly counts.  A hypervisor differs from other operating systems in the level of services it intends to provide.  ESXi intends to provide a minimum level of access to (virtualized) hardware, where are larger operating systems (Solaris, Linux) intend to provide more (like standard C libraries for applications, etc).

2) Possibly.  If the system was locally installed, parts of it (configuration files) are persistent.  Anything not specifically marked will not be maintained.  However, if the system is autodeployed, nothing persists between reboots, because all configuration is retrieved from vCenter on boot.

[kjb007]

Q1. ESXi is a bare-metal hypervisor, meaning it controls access to the hardware.  It is an "OS" to itself as it keeps process and provides access to hardware, but not a general purpose OS that most people are aware of.

Q2. Yes, and no.  Meaning changes to configuration files will persist.  Those file changes are copied back into the store that ESXi uses when it boots.  This is how configuration is changed.  You will not reconfigure a host each time you have to restart.

Not sure why you would be modifying the file permissions, but I haven't tested that myself, so i can't say for sure that mode changes will be saved.

-KjB

[Guardian1234]

Thanks for the response. I've only seen the locally installed scenario, Is there something (a tech article, etc) that you can point me to for a reference to auot-deploymeny from vCenter Server? Sounds like an interesting approach that I'd like to know more about. The company hasn't bought into vSphere yet, so I'll have to download either the vCS Linux appliance or get the app and install it onto a Windows server.

[Guardian1234]

Thanks for the response. Good article. Gave me plenty to think about!

[Guardian1234]

Thanks for the response. The permissions and owner/group thing has something to do with a possible gov't contract and apparently there are some specific checklist requirements that gov't purchases have to meet contractually. I wasn't given any details, the question was posed at a meeting by one of the sales engineers.

[kjb007]

You're not going to have typical "users" as you would on a general purpose OS.  For all intents and purposes, to do any sort of configuration,  you have to be root.  No sudo on ESXi, so root does everything.  But that's a last resort type of access.  It is used to get a host up on the network, and connect to vCenter. Once you're connected to vCenter, typical role based access applies, using AD.

You can setup AD auth for the ESXi host as well, but you're still going to use root to do that, and further to add permissions for other possible users to be able to perform tasks after the fact.

-KjB

[mcowger]

http://pubs.vmware.com/vsphere-50/topic/com.vmware.vsphere.install.doc_50/GUID-9A827220-177E-40DE-99...

[rickardnobel]

Guardian1234 wrote:

The permissions and owner/group thing has something to do with a possible gov't contract and apparently there are some specific checklist requirements that gov't purchases have to meet contractually.

Since ESXi is not intended to be used as a classical operating system it might be good to be very careful with changing permissions/ownership and other similar settings without verifying with VMware in advance that this actually is supported to modify.

[RanjnaAggarwal]

1. Esxi5 is a Hypervisor and hypervisor is a OS itself and also it is the platform for the bare metal virtualization that provides the resources to the vm.

2. Once booted you can login with root or any domain account if your esxi5 host is the part of the domain and the configuration is persistent and it is available even after the reboot of the esxi5 host.