Direct attach

Direct connection between the host and the array limits the number of hosts that you can connect to the array; and does not allow the multipathing solutions to work properly (data unavailability concerns if a particular path fails). Specially in the case of an XtremIO array - you might not be able to scale to the maximum performance potential because you might not have enough hosts driving enough IO to the array.

EMC has not tested the direct connect scenario and it is recommended that if the customer absolutely wants it - then have the EMC account team submit an RPQ asking for it to be supported/tested.

Thanks Avi, I think the customer was interested in this for a Test environment for customer demo purposes. But I will clarify. Many thanks for the feedback.

:-)

Many thanks!

Hi Miroslav,

When you say "the FC link doesn’t get reestablished after a reboot" are you refering to the host reboot, or the XIO Node reboot?

Also, what OS did you use for your testing?

We had an RPQ for Direct Connect using W2k8 R2.  We tested using PowerPath without any issues.  We tested cable pulls, array node reboots, and configured for SAN booting.

Thanks,

-Ron

Hi Ron,

It's been a while, so my memory is a bit fuzzy. From what I recall, the reboot in question was for the storage array controllers. It's a lab environment, and we were running frequent updates between alpha and beta builds that would do NDU reboots of the storage controllers as part of the update. The hosts were running ESX and using native multi-pathing (no PowerPath). If I remember, we could get the link back by rebooting the hosts, but an easier way was just to walk down to the lab to unplug and reconnect the fiber. At the time, I was thinking that the HBA's give up retrying the links too quickly. They should retry frequently at the beginning, but then go back to something like retrying once every 5 seconds indefinitely. A different brand of HBA, different driver, or even different OS might have different results.

Take care and hope that helps,

Miroslav

Thanks Miroslav.

Ron - please reach out to me offline and we can discuss this further. We are in the process of testing this in our labs and maybe we can share some notes :-)