BPLive
Contributor
Contributor

Studying CHAP // Confussion VCP410

Hey all.

My vsphere 4.1 Class Book states that ONLY Software ISCSI can use Mutual Chap.   Now reading from the iSCSI San Configuration Guide 4.1 it states that  both "Dependent Hardware & Software iSCSI" can use Mutual Chap.  So this guide ... along with this guide states:

http://www.vmware.com/resources/compatibility/info.php?deviceCategory=san&mode=san_introduction

Hardware iSCSI Adapter
A hardware iSCSI adapter is a third-party adapter that offloads iSCSI and network processing from your host. Hardware iSCSI adapters are divided into categories.

Dependent Hardware iSCSI Adapter: Depends on VMware networking, and iSCSI configuration and management interfaces provided by VMware. This type of adapter can be a card that presents a standard network adapter and iSCSI offload functionality for the same port. The iSCSI offload functionality depends on the host's network configuration to obtain the IP, MAC, and other parameters used for iSCSI sessions. An example of a dependent adapter is the iSCSI licensed Broadcom 5709 NIC.

Independent Hardware iSCSI Adapter: Implements its own networking and iSCSI configuration and management interfaces. An example of an independent hardware iSCSI adapter is a card that either presents only iSCSI offload functionality or iSCSI offload functionality and standard NIC functionality. The iSCSI offload functionality has independent configuration management that assigns the IP, MAC, and other parameters used for the iSCSI sessions. An example of a independent adapter is the QLogic QLA4052 adapter.
Hardware iSCSI adapters might need to be licensed. Otherwise, they will not appear in the vSphere Client or vSphere CLI. Contact the adapter's vendor for licensing information.
Please refer to the I/O Compatibility Guide for a list of hardware iSCSI adapters and NIC that can be used with ESX.

later there is a note saying: NOTE: Dependent Hardware iSCSI adapters are supported starting with ESX 4.1 and later versions.


So all this tells me that because of the definition of "Hardware iSCSI" that Mutual Chap is support by both Hardware iSCSI and Software iSCSI.

Please end my confusion as one book says one thing and the other sort of says another?

Also when I take the VCP test I should be answering questions with my knowledge of 4.1 opossed to 4.0 as there are many differences? 

thanks much,    BP

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5 Replies
scott28tt
VMware Employee
VMware Employee

Two very simple tips to answer your questions:

1. ALWAYS go with the answers in the vSphere documentation - http://www.vmware.com/support/pubs/vs_pubs.html - those documents were used when making sure each item in the exam was valid.

2. The exam is equally applicable to 4.0 and 4.1 - the answers to each question in the exam are true for both versions.

Scott.


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VMware Training & Certification blog
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BPLive
Contributor
Contributor

Hi,

I listed the vsphere "iSCSI San configuration Guide esx(i) 4.1" as a reference which is also outlined (or pointed out) by the VCP Blueprint Guide. So this is where I can getting the information from.

Also my official 4.1 vsphere classroom material from vmware states "Software iSCSI only" when it comes to "Bidirectional CHAP"  and also "Software iSCSI only" for  per target CHAP. This also goes for many books referring to "hardware" as just known as 'independent'.

From reading vmware terms.....  "Hardware iSCSI" is broken down to 1. Dependent Hardware 2. independent hardware.

vmware through the official guides (san guide I mentioned above) also refer to "Hardware iSCSI" to only Independent hardware.... even in one sentence in the guide above "Hardware iSCSI supports CHAP only at the initiator level".  :smileyplain:   but in the next terms change.

So which is it?

According to you if I was asked......     answer would be:  Mutual CHAP is supported by both Hardware iSCSI and Software iSCSI.    I think ....    what am I missing :smileysilly: ??

Dependent hardware iSCSI is not "Hardware iSCSI"?

What is 'hardware iscsi"?

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scott28tt
VMware Employee
VMware Employee

Page 98 of the ESXi Configuration Guide:

http://www.vmware.com/pdf/vsphere4/r41/vsp_41_esxi_server_config.pdf

Page 44 of the iSCSI SAN Configuration Guide:

http://www.vmware.com/pdf/vsphere4/r41/vsp_41_iscsi_san_cfg.pdf

They both state:

"VMware supports this method (Mutual CHAP) for software and dependent hardware iSCSI adapters only."

As the support for dependent hardware iSCSI adapters was new to vSphere 4.1, you won't get asked any questions that refer to them, due to the 4.x nature of the exam items. If the exam refers to a "hardware iSCSI adapter" I would be answering the question as if it said "independent hardware iSCSI adapter".

Scott.


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VMware Training & Certification blog
BPLive
Contributor
Contributor

Thanks Scott & I sort of figured that, but really it is not accurate information being stated.

so

1. The 4.1 classroom book is wrong and doesn't even mention 'dependent hardware'.  and by stating "software only" shows me a little bit of rushing to get out the updated books. or maybe I'm being picky... but hardware is hardware.

2. Those guides should specifically state "Independent Hardware" instead of just saying "Hardware" being that you can setup CHAP on both a hardware device and software device that can both support mutual CHAP.

I am not only looking out for me or even the test.  In general I think it should be distinguished.

but ..... 1.   in your class if you come to that page to teach your students ....   (I ask because maybe I'll instruct at some point in time),,,  do you tell them the slide is inaccurate?   or do you just go along with it because 'on the test' vmware refer's to Hardware as "Independent".

In the Introdution to San guide it clearly states that "hardware" is independent AND dependent for vmware terminology.     So yes this should be a correction.  Its 3 books/guides   (1 very expensive book)  all stating different terminolgy or bold statements.

/rant over... i'll move on now :smileylaugh:   ==  sorry if you think this is silly.   -BP

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jonhall
Expert
Expert

Hi all,

This is more a "terminology change"  Before a dependent hardware adapter was introduced, there was only hardware and software.  It was only after 4.1 that there is a distinction between dependent and independent hardware.  Because the terminology change is recent, I wouldn't be surprised if some materials still use hardware to mean independent hardware.

Jon C. Hall Technical Certification Developer VMware, Inc.
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