Which Server Profile Template to Use for iSCSI Boot

[sparkesma65]

Hi

We have have an updating server profile template applied to five blades to configure for booting from a SAN via iSCSI

First time we have set this up so the learning curve has been steep and we discovered that each server needs a separate target initiator and therefore there is no need to configure the boot parameters in the server template for the iSCSI vNICs as the static target will be different per server

So i believe we really need a initial template as we will build the servers from this template and then edit the boot parameters in the server profiles - any subsequent changes will need to be done manually 

However if we use a updating template to apply changes across servers - if we leave the boot parameters blank on the template - would this when subsequently applied for a change clear the manually configured boot parameters?

If so then we will use a initial template 

[Kirk J]

You generally use initiator IQN and IP pools to auto assign those IDs.

Please take a look at the iSCSI section of one of our flexpod guides: https://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/UCS_CVDs/flexpod_datacenter_vmware_netappaffa.html#_Toc24113091

Kirk...

[sparkesma65]

Hi

Sorry haven't explained my self very well - yes we have all the host/server initiators set up via the template i.e. IQN pool etc its 

Service Template and iSCSI Boot Parameters 

So the service profile requires the two different IQNs one for the initiator/server and one for the target/storage_array. 

So its the target/storage_array in the boot parameters - I didn't get this across very well- the SAN we have has to have a separate target initiator for each server to allow the creation of a LUN ID 0. So we know we cant include the static  storage_array target in the template as we have to manually edit the target IQN for each server hence question around which template would be better to use - initial or updating still and the question if updating - would applying a new setting overwrite the manually entered target IQN with blank entry from the template as it would differ from each server profile

[Kirk J]

What iSCSI storage solution do you have?

Normally, you can point your servers to the same target IP/IQN, and you do 'lun masking' on the storage controller side to control access to which Initiator has access to each LUN you are using for booting.

Kirk...

[sparkesma65]

Hi

Its Intelliflash SAN - (manufacturer was Tegile- then Western Digital now TinTri/DDN)

This was the solution provided by the Technical consultant for the storage

It works on a 'project' template to apply to group of LUNs you create within the project pre-defining block size and protocol used setting the target IQN then applying initiator group containing the initiator for the host(s) for access of the project and subsequent LUNs you can override stuff at the LUN level as well

yep we originally set it to point to the SSD flash pool IQN and expected to do the masking on the storage but couldn't get it to work went back to DDN and this was the advice given

[Kirk J]

Unfortunately, requiring unique IQN/IP targets, is not going to scale.

The UCSM boot policies do not contain the concept of target IQN pools, as that is not an industry standard (that I have ever seen).

Could it be implemented in UCSM? Sure,,, but there wouldn't be a business case to do that unless we saw an industry shift with that kind of config for iSCSI.

Kirk..

[BWetteroff]

Kirk is correct,

This boot from iSCSI should be possible from an updating template, without the overhead of re-creating everything for each individual service profile.  The Storage Array does the LUN masking to only allocate the LUN to the assigned IQN, you will need a new LUN for each host, and only assign that individual IQN access to it's individual boot LUN.  You should then be able to create initiator groups on the storage array, and assign those to the aggregated LUNs for your datastores or w/e OS you are using.  I believe you are having some configuration issues, and this might be on the storage system, UCS, or networking and you might want to get a better understanding of the environment and capabilities.  These are a few of the available PDFs that I found that show setting up an intelliflash array with UCS and have iSCSI boot options.  I have not read through and verified these documents, but would suggest reading these and see if they have an answer to your issues.  I would also suggest reaching out to tintri and seeing if you can get access to their Intelliflash user guide if you don't already have it.  I would also  suggest researching UCS iSCSI vNICs, and best practices with which ever OS you are utilizing for the boot.  iSCSI storage and how a SAN function are not usually different between storage vendors, as they all have a standard of operations on how to present storage, so the hosts know how to utilize it. 

https://tintri.com/download/intelliflash-best-known-methods-vmware-vsphere/?wpdmdl=6765&refresh=5eb2e5ce970ff1588782542

https://www.flasharrayguard.com/datasheets/tegile-report-intelligent-flash-array-cisco-ucs-configuration-guide.pdf

https://tintri.com/download/intelliflash-best-known-methods-vmware-vsphere/?wpdmdl=6765&refresh=5ebc4a12ae53f1589398034

[sparkesma65]

Hi

Thank you for the answers - I appreciate your help and all of what you have said has been done so the servers are all 6.7 latest update of ESXi which is configured as per document links in Tintri and best practices from VMWare etc.

TinTri have been involved as Cisco have and have told us this is the way we need to configure the SAN side for multiple target of LUN ID 0  using multiple IQN targets one per server basically - this works and we have accepted this - my question was from now on do we still use the template as a updating or a initial template for the servers as we have to manually add the target in boot parameters 

[sparkesma65]

Hi actually found this post on the community which is same problem we had with the array we use and this one is Nimble so at least two vendors doing the same

https://community.cisco.com/t5/unified-computing-system/service-template-and-iscsi-boot-parameters/td-p/2404553

[sparkesma65]

Sorry one more thing didn't make clear the reason for the different target initiators we cant then use LUN ID 0 for each server if we use same target initiator it increments the LUN ID and we cant change that - so 1st servers may be 0 next will be 1 and so on - so we would be back to editing the server profile again

[BWetteroff]

Thanks for the follow up, good to know about these issues.