Wednesday, November 7, 2007

Host Connectivity Limitations






This page is going to discuss how many hosts can connect to a Clariion. The deciding factor in this is going to be the number of times you connect your host(s) to the Clariion. We are going to use the three configurations that were discussed in the prevoius blog. The chart above lists the number of ports each Storage Processor contains based on the model, as well as the number of Initiator Registration Records each port supports. An Initiator Registration Record (IRR) is used everytime a host, via an HBA, is connected and "Registered" with the Clariion. The Clariion now recognizes that this HBA belongs to a specific host attached to the Clariion, and will now allow the host to "talk" with the Clariion. The more times you connect and register a host, the more IRRs it uses, thus taking away potential connections for other or more hosts.

With Configuration One, even though it only has one HBA, that HBA must be connected at least once to SP A and once to SP B. Again, this goes back to the previous blog about access to the Clariion if a LUN were to trespass. Therefore, this host is using two IRRs.

With Configuration Two, this host has one connection from each HBA to one SP Port on each Storage Processor. Even though this host has two HBAs, it is still only using two IRRs. One connection to SPA, one connection to SP B.

With Configuration Three, this host has two connections to the Clariion from each HBA. HBA1 is connected once to SPA and once to SP B. HBA2 is connected once to SP A and once to SP B. This host is using four IRRs because it is connected four times to the Clariion.

In the chart, we are trying to illustrate the maximum number of hosts that can connect to a Clariion based on the host configurations. Again, the more times you connect a host, the more IRRs you use, the less the number of hosts that can be attached to a Clariion. If you are using a CX700, CX3-40 or CX3-80, you have the possibility of hooking up 256 hosts based on each host only having one connection to SP A and one connection to SP B. However, if every host were connected four(4) times, as in Configuration three, that number is cut in half to 128 hosts. If every host were connected to the Clariion eight(8) times, the number is cut again to 64 hosts.

2 comments:

Anonymous said...

please add the picture for "host connectivity limitations" post. we are not able to open it.

Anonymous said...

Can you list host connectivity updates on cx4.