ASM ME with vSphere Raw Device Mapping (RDM) on PS6000

I'm not familiar enough with ASM to answer most of this, but one thing I would recommend is to go into the access control list for each volume and allow the vSphere box(es) only access to the volume and not the snapshots; the snapshots should never be given back to a server that sees the original when using vSphere... it can cause some serious side-effects.

Not sure what "side-effects" you are referring to.    VMFS volumes can deal with snapshots/clones/replicas w/o issue.  Just have to resignature them.

On the guest side that's OS dependent.   I.e. mounting a snapshot of a dynamic disk on the same Windows server is bad, that can cause a BSOD.   Is that what you meant?

-don

I missed your last question.  The newest HIT kit,  keeps the snapshots offline by default now.

-don

Hello,

 You can create a smartcopy with an RDM because the Vendor info is being passed up to the host.  However, if you try to recover a snapshot it will fail.  The only support model for ASM/ME is a "Storage Direct" (SD) connected volume.  Where the MS iSCSI initiator is handling the iSCSI session, not the ESX iSCSI initiator.  You can go from a RDM model to a SD model.   First shutdown the VM.   Put the RDM volume offline, rescan all ESX servers.  Change the ACL of the volume so that only the MS iSCSI initiator can access it.   Put volume online.   Bring up VM, connect to it from inside the Guest.  Now ASM/ME will work properly.

Regards,

-don

Thank you for pointing that out. I updated the hit and can confirm that the created snapshots are offline.

Good point with the failure of restore from snapshot... hadn't had the time to test that yet. Good thing it's only a testsystem ;-)

I will change the sql server volumes back from RDM to iSCSI attached.

Hello Mr Jäger,

You are correct – I got confused.

It doesn’t work with RDM, ASM ME only works with volumes connected directly thru iSCSI initiator. RDM is instead presented as local disk by VMware, so is not supported. Sorry for the mixup.

I know RDM would be nicer, because you can manage it from ESX…

I have a nice article from our knowledgebase available on www.equallogic.com/support:

ASM/ME (Made available to customers with the Host Integration Toolkit or HIT kit) is a feature of the EqualLogic storage solution that coordinates the creation, recovery and scheduling of Volume Shadow Copy Service (VSS)- compliant Dell™ EqualLogic™ SAN-based snapshots of Microsoft® Exchange Server, SQL Server® and Windows® NTFS volumes, as well as Hyper-V™ virtual machines. Volumes that are connected by the MS iSCSI initiator using NICs or Qlogic 4xxx iSCSI HBAs, (excluding Qlogic iSCSI HBAs with VMware ESX) can leverage features of the Dell Equallogic array. The use of the MS iSCSI initiator is a requirement for HIT kit support. 

ASM/VE on the other hand, works with VMware vCenter and VMware’s native snapshot technology to coordinate the creation, recovery and scheduling of PS Series snapshots and replicas. ASM/VE helps enhance protection, storage utilization, and performance of VMware-based virtual infrastructures. The resulting Hypervisor-aware snapshots and remote replicas can now be easily and rapidly created, managed, and recovered. Integrated directly with standard VMware application programming interfaces (APIs), Auto-Snapshot Manager/VMware Edition understands the relationships and location of virtual machines, VMFS Datastores, and PS Series SAN-based volumes. 

ASM/ME and ASM/VE are complementary products. For example, in a VMware-based virtual infrastructure running Microsoft Exchange in a VM, ASM/ME can be installed in the VM hosting Microsoft® Exchange to provide application-aware protection of Microsoft® data. Because the Microsoft® data volumes are a subset of the full VM they may require more frequent snapshots. Using ASM/ME in this manner gives you more granularity in your data protection strategy and helps make more efficient use of your storage capacity. In this same scenario, ASM/VE can be installed to provide application consistent snapshots at the VM level. This configuration is known as “Storage Direct” by VMware and it allows the storage manager to schedule a different (possibly less frequent) backup schedule for the full VM. 

Note: This does NOT include Raw Device Mapped volumes (RDM). The MS iSCSI initiator, not the VMWare initiator must be making the connection to the volume in order for ASM/ME to function.

I hope that clears it up.

Kind regards,

***********

interesting news:

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Case ******** - ASM ME and RDM in vsphere on PS6000

Hello Mr. ****,

I have taken ownership of this case. What you describe should be OK, can you perhaps point me to an article that says otherwise?

We support ASM/ME inside virtual machines, with RDM.

Kind regards,

**************

Senior Storage Analyst

Dell | EMEA Enterprise Expert Centre