Adding another nimble to a existing group - Same iscsi data subnet?

[Koobster]

I will be getting a 2nd nimble array and adding it to the existing group from our first nimble. I know in terms of management it will be sharing the same management IP with the exception of the diagnostic IPs for controllers A & B.

But what about the iscsi data subnet? Do they typically share the same subnet as original nimble and we just assign static IPs on the new nimble ports? Or does the new nimble need a seperate subnet? Can someone also provide me a whitepaper/config guide where i can see the best pratice for this?

Im sure whoever they are sending out to help do the install/config can answer my question but id like to know in advance.

[Thomas_Lam_HK]

All arrays within the same group needs to have same IP subnet on both management and iSCSI data.

For management, the 2nd array will also use the existing Group management IP (typically the 1st array) as you mentioned, therefore only diagnostic IP on ctrlr A & B on 2nd array are required.

For iSCSI, same principle applies which the 2nd array will leverage the existing iSCSI discovery IP in the group, hence only new data IPs are needs to assign to each iSCSI data interface and therefore same subnet will be mandatory.

Please note that all host will need to have NCM properly installed!!

And with the correct iSCSI discovery IP being setup, any array side operation such as pool merge or volume move will then be transparent to both host and application and thus make the life much easier....

[Syed Ehtisham]

Dear Thomas,
         Just a quick question not related to the subject but i got in mind to ask is What is the volume write behaviour after adding a new array to the group? As old array having many volumes and new array do not have any volumes. Will the data will strip and balance accros both arrays?

[Nick_Dyer]

Hello,

by default, your new array within the group will reside in a separate pool. Volumes do not span pools by design, and thus if you want to move volumes you can head to the 'data storage' screen, and click the 'move' button to move volumes from one pool to another. This is non-disruptive to the application.

You can also merge pools, and have two arrays unified in a single pool (this is where volumes will stripe across both systems). However, you should only do this if both your arrays have the same capacity and performance, otherwise you could end up with staggered performance or capacity - which isn't a great idea. Also, you can't have a mixed pool with all flash and hybrid arrays, or dedupe and non-dedupe arrays.

For both of the above options, you must have Nimble Connection Manager installed on all your application servers/hosts that are accessing Nimble Storage.

[aquanta]

Hi Thomas, a query when adding a new Nimble to an existing group, what happens with the space that is added, is it added to the existing POOl unifying the spaces or are they independent spaces?