Initiator Types (what are they for) and LUN Types - Hyper-V

[williamlee650]

Questions:

1. What setting the initiator type even does, there is no real explanation to what the type does or why you need it, the manual on the filer doesn’t go into any details.

2. What initiator type do you give a hyper-v host that boots from os with multiple hyper-v luns on different controllers?

Situation: You have a Hyper-V host server which boots from san.... so you have a lun type windows2008 for the host os with a initiator of what I would think is best "windows"... then you create  a vm lun using type "hyper-v" .... how can you make a initiator with the same WWN with the hyper-v type?  Also another problem is if you have two controllers with a os and vm lun on one and another vm lun on the other, now you would have to have two initiators on both controllers for the same HBA/WWN, problem is you cannot do that because the filer will throw you an error.

3. Is there even a difference in windows2008 and hyper-v luns?

4. If you have a child Hyper-V OS LUN which will run windows 2008 ... do you use hyper-v or windows2008?

5. This just plain bugs me ... from some documentation it says that  if you use system manager that it will create a windows-gpt type lun when making them for hyper-v.... now why would that be different if you’re making the lun from cli and using hyper-v.  If its going to be a hyper-v lun and they have a hyper-v type why would netapp not use it in their own management tools?  Which bring me back to a simple question what is the difference and if there isn’t one why are they even there.

[sheastewart]

Hi,

Here are a couple of relevant documents that may help out...I would focus on the sections that describe filesystem aligment and how this applies to your hyper-v/netapp environment:

http://media.netapp.com/documents/tr-3702.pdf

http://media.netapp.com/documents/tr-3747.pdf

Hope this helps

[williamlee650]

I looked through both the documents below and they do not answer my questions, there is no detailed explanation as to what the initiator types are or what they are for.

Also from the documentation it says to make the initiators from the manager, what if the host 2008 r2 is boot from san?  What do you use for the initiator type of that hyper-v or windows 2008?

The documentation does say that if using their tool or using cli that you can get either windows-gpt or hyper-v or windows 2008 lun type..... so why would it be any different from cli or using the manager.  That’s not only confusing it doesn’t make any sense as to why it would be different if the tool is doing essentially what you are doing from cli.  It also brings up more questions, is one better than the other? what if I made a windows-gpt type from cli, do I have to go back and redo the lun since the doc says to use the other?  Is there really a difference in the types? 

[lwei]

The info below (thanks to Chaffie McKenna) may be what you are looking for. Also, please check the info at: http://wikid.netapp.com/w/ONTAP_Blocks/Lun_Types

Selecting the correct LUN Protocol Type

When creating the NetApp LUN using the FilerView or CLI, the parameter “LUN Type” plays a very critical role. This parameter determines the on-disk layout of the LUN. It is important to specify the correct LUN type to make sure that the LUN is properly aligned with the file system on it. The underlying reason is that optimal performance with the storage system requires that I/O be aligned to a 4096-byte boundary. Unaligned I/O may cause an increase in per operation latency. Unaligned I/O requires the storage system to read from or write to more blocks than necessary to perform logical I/O. This issue is not unique to NetApp storage. Any storage vendor or host platform may exhibit this problem.

The LUN type you specify depends on the OS, OS version, disk type, and Data ONTAP version. If the incorrect LUN type is selected when the LUN is initially provisioned, a new LUN (with the correct LUN type) will need to be created, and the data will need to be transferred from the existing misaligned LUN.  For complete information on LUN types for different OS’s, see the Block Access Management Guide for your version of Data ONTAP.

Please review Table 1-3 below to determine the LUN types to use when configuring LUNs for use with Windows Server 2008, for installations with and without the Hyper-V role enabled.

Table 1) LUN Types for use with Data ONTAP 7.3.1 and later

Data ONTAP 7.3.1 or later	Windows Server 2008 Physical Server w/o Hyper-V	Windows Server 2008 Hyper-V Server Physical Disk	Windows Server 2008 Hyper-V Server Pass-Through Disk
With SnapDrive installed	windows_gpt	hyper_v	LUN type of Child OS
Without SnapDrive installed	windows_2008	windows_2008	LUN type of Child OS

Table 2) LUN Types for use with Data ONTAP 7.2.5 through 7.3.0

Data ONTAP 7.2.5  through 7.3.0	Windows Server 2008 Physical Server w/o Hyper-V	Windows Server 2008 Hyper-V Server Physical Disk	Windows Server 2008 Hyper-V Server Pass-Through Disk
With SnapDrive installed	windows_gpt	windows_gpt	LUN type of Child OS
Without SnapDrive installed	windows_2008	windows_2008	LUN type of Child OS

Table 3) LUN Types for use with Data ONTAP 7.2.4 and earlier

Data ONTAP 7.2.4 or earlier	Windows Server 2008 Physical Server w/o Hyper-V	Windows Server 2008 Hyper-V Server Physical Disk	Windows Server 2008 Hyper-V Server Pass-Through Disk
With SnapDrive installed	linux	linux	LUN type of Child OS
Without SnapDrive installed	linux	linux	LUN type of Child OS

For Data ONTAP version 7.3 and earlier, the LUN type “windows_2008” is available only through the Data ONTAP CLI. Therefore, the LUNs for Hyper-V parent partition and Windows Server 2008 Child VMs must be created through the LUN setup command on the Data ONTAP CLI.

For LUNs directly mapped to the child OS using the iSCSI software initiator running in the VM, the LUN type of the intended child OS should be selected when creating the LUN.  In addition, for LUNs assigned directly to the Child OS via a Pass-through disk configured for the Hyper-V server, the LUN type of the intended child OS should be selected when creating the LUN.

Hope that helps,

Wei

[aborzenkov]

Also, please check the info at: http://wikid.netapp.com/w/ONTAP_Blocks/Lun_Type

Unfortunately this is internal-only link

Selecting the correct LUN Protocol Type

Was not the original question about initiator type, not the LUN type? I am interested in this as well.

[lwei]

Sorry about the internal link. The tables really have the details. Also, sorry for the confusion. Correct me if I'm wrong; I think the "initiator group" type and LUN type should match.   -Wei

[aborzenkov]

Correct me if I'm wrong; I think the "initiator group" type and LUN type should match

No, I know several cases (mostly including virtualization of some sort) where initator type is required to be set differently from LUN type.

Lack of infornation is really frustrating. I once stumbled upon kb article that described LUN type in pretty much details. Unfortunately I did not save it and apparently it was considered too dangerous and removed from NOW since then

[lwei]

Could you please elaborate on the cases where initiator group type is required to be set differently from LUN type? What types should they be set, respectively? Thanks,   -Wei

[aborzenkov]

Egenera BladeFrame provides virtualization environment where IO to raw LUNs is tunneled through control nodes running Linux. So initiator type has to be set to Linux (because only control nodes have direct access to storage) but LUN type has to be set to match guest (called pServer in BF) type to ensure ... whatever is ensured by setting LUN type

And if you consider more widely known ESX with RDM, you have the same issue. It is ESX initiator that storage sees; there is no way to configure multiple types to match every guest.

[williamlee650]

From the chart does that mean if I have snapdrive installed that even if i make the lun from cli (which I would be) do I still use the lun type of "with snapdrive installed" or do I make it something else since were doing it from cli?  You see how netapps approach to having different standards for different software being installed or weather or not its created using the software or cli is so ******* confusing.  If its all being pushed back to the filer with the same commands .... why.