Multi-Cluster XMS Scalability Limits

Thanks Avi...I will try to stay close to my account team as well. With one of my customers, I think I am going to break it back down to a 1:1 mapping of XMS to XtremIO array for the time being since RP replication is in place and I have concerns around the snap counts being global.

so if you are managing two distinct XtremIO clusters with one XMS, you can only create 8192 volumes between the two ?

dynamox  - thats correct. The maximum number of LUNs (8192 at this time) is defined at the XMS level. So, if you have two separate clusters being managed by the same XMS, you can have a maximum of 8192 LUNs across those two clusters.

Avi,

Thanks.

Oh boy does XtremIO have a long way to go to catch up to your other element managers (Unisphere for VMAX and even VNX Unisphere). Let's assume someone did not know about this limitation, can they break off one cluster from an existing XMS and have it managed by another XMS ?

Hi Dynamox,

I have to do just this now given the VIAS limitations and after reviewing with EMC and having done something similar for a customer that lost their XMS, the answer is yes and the general process (to be performed by EMC or authorized personnel) is this:

1. Deploy a new 4.x OVA
2. Upgrade the OVA to the cluster version of the array you will be adding to it so they match (EMC/Partner does this)
3. Remove the cluster from the existing multi-cluster vXMS

   4.  Add the cluster to the new vXMS

I'm sure others will chime in from EMC if I am off base.

Re: “Let's assume someone did not know about this limitation, can they break off one cluster from an existing XMS and have it managed by another XMS?”.

Answer – yes. You can do that. You can always move the XtremIO from one XMS to the other. There are CLI commands (remove-cluster and add-cluster) that does exactly that.

Hi,

You can find setup doc at https://support.emc.com/docu59666_XtremIO-4.0,-4.0.1,-4.0.2-and-4.0.4-Storage-Array-Software-Installation-and-Upgrade-Gu… under the section Installing XtremIO in multiple cluster configuration.

by Avi on Dec 15, 2015 7:54 AM Thanks for the feedback Keith. We are looking at improving those scalability numbers in multiple ways. You will some of these numbers changing in our future releases. I don’t have a committed date for that change at this point of time.

Just wanted to note, that 2 years after this comment, these limits are still in place, as per Release Notes for 4.0.25-27 (P/N 302-004-060, REV 02, October 17, 2017). Per those release notes, the scalability numbers of the XMS have not changed since at least 4.0.0-64, circa June 2015 (that was the earliest release note available in SolVe Desktop for XtremIO 4.0, which was when multiple clusters per XMS was introduced).

Iris,

How soon is "soon",  i have two X2 on the floor waiting to be installed.  Waiting on NVRAM replacement cards first.

Thanks

X2s? Cool!! Are those your first XtremIOs?

We have had X1 for about 3 year now, good array, easy to manage.

but that seems to be a trend: Unity hasn't got host groups either. That takes more time to mask LUNs to a group of hosts. I wish they would put host groups back in Unity and introduce them to XtremIO.

oh yeah, absolutely! I miss host groups though, like the VNX has.

look into XtremIO tags, allows you to do a lot of things based on tags instead of individual volumes for example.