I was at a customer site helping out configuring SRM yesterday. During the configuration of the EMC SRDF SRA(Storage Replication Adapter) we ran into a weird issue. Although we could see the paired arrays with a green “okay sign” we did not see any replicated LUNs. First things I usually check in these cases are:
- Is the LUN already formatted as VMFS
- Does it hold any VMs
In this case we met both requirements. After checking all the configuration settings on the SRA side, SRM side and the SAN we noticed that the SPC-2 bit was not enabled. Of course we knew that is was a required setting according to the FC San Config Guide(page 57) but this is definitely not the kind of behavior I would expect to see when it’s disabled. Anyway I did a quick search on our internal mailing list and as it appears we were not the first to encounter these issues.
The SPC-2 bit is something that comes up every now and then, so if you’ve got EMC Symmetrix storage and you are not sure whether you have applied VMware’s recommendations please read the FC San Config Guide and avoid future problems. Please bare in mind though that when you set the SPC-2 bit you might and probably will need to re-signature the disk.
itzikr says
Hi Duncan,
you can set the SPC-2 and SCSI3 flag on the initiator level, rather than the FA ports
some OS’s are not compliant with SPC-2 flag, so the initiator approach may be more suitable..
also, in regards to SRM, we have released the SRDF SRA adapter ver 2.0 which is conjuction with EMC storage viewer let’s you select the source / target luns for both the DR and the SRM testing..
more of it in the coming VMworld..bala ganeshan and myself will give a customer / EMC lecture about the SRM project and the new SRDF SRA 2.0 adapter
Duncan Epping says
I know there’s a V2 cause I used it for this engagement. I also know you can set it on the initiator instead of the FA ports but this does this change the behavior? (I don’t think it will…)
It doesn’t make sense I my opinion that you need to install the storage viewer to get the functionality you would expect from the SRA!
Besides that the Storage Viewer documentation actually mentions issues when the SPC-2 bit hasn’t been set but the SRA Documentation doesn’t.
itzikr says
Duncan,
the SRA behaviour is the same with or without the EMC storage viewer..it just that we leverrage the storage viewer to help customers who deploy SRM over the symmetrix array.
the SPC-2 and SCSI-3 flags are pre-requisites for a supported VMware deployment..hence why they may not be in the SRM document..
VirtualGeek says
To be crystal clear, setting the SPC-2 flag and SCSI3 by initiator (i.e. host) rather than at the FA port is a good idea, as an FA port can (and likely) does support many different hosts.
Duncan, configuring it at the initiator level works fine, and would resolve the issue the same way it does at the FA port level, but doesn’t impact any other hosts.
To those folks who have mid-range storage arrays, this whole idea of SPC-2 bit setting (or changing the SCSI device type on a host-by-host basis) may seem wierd and foreign, but Symmetrix (like most enterprise-class storage arrays) need to be able to connect to ALL sorts of crazy systems, including non-open systems. Some of these ones, including mainframes, need the storage target to look like a very specific device.
With more and more hosts attach being open systems, and heck even VMware specifically, I’m happy to say that the SPC-2 flag being enabled (and SCSI-3) is now the default in the latest Enginuity builds (and not the other way around).
BUT – Duncan and Itzik are both right – it’s always a good idea to check on customers with older Symms. It’s actually important GENERALLY with vSphere, not just in the SRM use case… If you follow the Symmetrix Applied Tech Guide, it emphasizes these host configurations throughput… You can read it here, and should be mandatory for any VMware shop using Symm.
(WARNING – big download – 23MB)
http://www.emc.com/collateral/hardware/solution-overview/h2529-vmware-esx-svr-w-symmetrix-wp-ldv.pdf
itzikr says
Lastly,
there is a great VMware KB shows in details how to do it..
http://kb.vmware.com/Platform/Publishing/attachments/1002835_dSymmetrix_Flags_and_VMFS.doc
Itzik
Astro says
Do I need SCSI-3 Resv set in my open system FA’s to order to use SCSI 3 dev resv locks?