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VPLEX IT Nexus limit and number of initiators
Hi,
As per VPLEX Elements performance testing best practice white paper it supports 1600 host Initiators per VPLEX. Is that mean we can connect 800 hosts ( dual HBA) to single VPLEX?
Whereas VPLEX release notes configuration limit
Storage views 1000
IT nexus per cluster in a VPLEX Local 3200
IT nexus per back-end port 256
IT nexus per front-end port 400
My question is how many hosts we can safely connect to single VPLEX ( local with dual engines) ?
What is IT nexus per cluster 3200 limit ? what is back-end port 256 limit ? what is IT nexus per front end port 400 limit ?
I am really confused about those numbers. ( storage view 1000, host initiators 1600) Can someone explain it .
Thank you.
echolaughmk
522 Posts
1
January 25th, 2016 11:00
Hello,
An IT-Nexus is defined as an Initiator-Target connection. In the VPLEX’s cases we have this type of connection at both the Front-End and Back-End levels for hosts and array connectivity respectively. While they are separate limits, it is important to know how they are incremented in order to ensure you don’t pass the limits for the cluster or the port.
In the VPLEXCli, when looking at the initiator-port context of a cluster’s ports, you can decipher the login table which will pretty accurately depict the IT-Nexus connections for that specific port. The trouble with this output is that while it is accurate, it is not easily aggregated to present a sum of IT-Nexus counts per port without manual counting or a savvy script.
VPlexcli:/clusters/cluster-1/exports/initiator-ports> ll -f
Name port-wwn node-wwn type Target Port Names
------------------- ------------------ ------------------ ------- --------------------------
AIX1_HBA2 0x10000000c9b64834 0x10000000c9b64834 default
ESX35a_HBA1 0x2101001b323c22c1 0x2001001b323c22c1 default P000000003CA007D3-A0-FC00,
P000000003CA007D9-A0-FC00,
P000000003CB007D3-B0-FC00,
P000000003CB007D9-B0-FC00
ESX35a_HBA2 0x2101001b323cf0b1 0x2001001b323cf0b1 default P000000003CA007D3-A1-FC00,
P000000003CA007D9-A1-FC00,
P000000003CB007D3-B1-FC00,
P000000003CB007D9-B1-FC00
ESX35b_HBA1 0x2101001b323c4fb1 0x2001001b323c4fb1 default P000000003CA007D3-A0-FC00,
P000000003CA007D9-A0-FC00,
In the example above, the VPLEX FE port P000000003CA007D3-A0-FC00 has 2 IT-Nexus counts against it because 2 HBA's are logged into it. The same type of summation and logic can be applied to the BE IT-Nexus counts as well. For a dual-engine config, the limits are cluster-wide and therefore just become a function of managing the connections you have. If you environment is fairly small in terms of numbers and arrays behind a VPLEX, this limit is usually not concerning for a dual-engine setup. If you have a giant environment behind the VPLEX, this limit can be something you want to monitor.
HTH,
-Keith