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Application Optimized Storage for VMware makes Life easy

by Hu Yoshida on Nov 15, 2005

David Simmons, a Hitachi Data Systems Consulting SE, reports that Application Optimized Storage makes life easy for EMC VMware users.

“At a customer site today – they are running VMware ESX Server.

Their comment was “HDS storage makes VMware so easy to use compared to EMC DMX systems.”

What they meant was that our Host Storage Domains technology makes allocating storage a snap since each Vmachine can have its own LUNs, and there’s a LUN scan setting in VMWare which the default is 8, if set too high will result in long rescan times.

On EMC it needs to be set high because you never know what the LUN numbers will be.

When they allocate on a DMX system, no Vmachine gets access to LUN0 (the Volume Logix Database is always LUN0 it seems), and since they don’t have Host Storage Domains, LUN numbers can be scattered, making management more difficult.

Guess EMC isn’t big on integrating what they absorb into the collective.”

Host Storage Domains is an Application Optimized Storage feature of our TagmaStore family of storage products, as well as the Lightning 9900 V Series and Thunder 9500 V Series storage systems. No other storage vendor has been able to provide a similar capability. Host Storage Domains enable a user to virtualize physical FC storage ports and create up to 1024 virtual ports per physical port on the TagmaStore USP or up to 128 virtual ports per physical port on the Thunder 9500 V Series. Each of these virtual ports is assigned its own address space, (Host Storage Domain) with its own contiguous set of LUNs starting with LUN 0. In the case of VMware, each Vmachine can be assigned its own virtual port and Host Storage Domain with consecutive numbered LUNs starting with LUN 0. Each Host Storage Domain can also be mode set to a different server platform, like Windows, Sun, HP, etc. Mode sets are required to insure that the server specific SCSI code page is enabled for that server’s set of LUNs.

Without this feature, each physical port would have to be mode set to one server platform, and would be limited to one set of LUN numbers. This means that only one type of host server could share the same physical port, and all these servers would have to carve out their LUNs from the same set of consecutive numbered LUNs. Only one of these servers would have access to LUN 0 which is usually reserved for boot access. One server may have LUNs 0, 1, 2, 7, 8 and another may have LUNs 3, 4, 5, and 6. This would not happen with Hitachi Storage Systems. One server would have a Host Storage Domain with LUNs 0, 1, 2, 3, 4 and the other server would have a Host Storage Domain with LUNs 0, 1, 2, 3 even though they accessed the same physical port. Each server would only see the LUNs in its assigned Host Storage Domain. Most servers have no awareness of sharing storage. Additional LUN zoning software is used to keep the hosts from accessing each other’s data. Depending on how the LUN zoning is implemented, it may not have effect during a boot process. During a reboot, a server might assume that all the LUNs that it discovers belongs to him alone, and writes a signature on each LUN it sees. This is upsetting to other host servers that are trying to use the same physical port.

Host Storage Domains provides “safe Multi-Tenancy” for multiple host servers sharing the same physical FC storage port. This is the difference between each tenant having its own private room (Host Storage Domain) or sharing a common dormitory with a bunch of other tenants.

VMware is a great product for server consolidation. It allows a user to stack applications on the same physical host server. However, it needs storage that can be optimized for this type of consolidation. The TagmaStore USP, NSC, AMS, and WMS, Lightning 9900 V Series, and Thunder 9500 V Series all provide the ease of consolidation and safe multi-tenancy required for this environment. In addition to safe multi-tenancy, the TagmaStore USP and NSC add a logical partitioning capability that can ensure a quality of service for a host server, by preventing other host servers from stealing common resources such as cache.

VMware and HDS Application Optimized Storage are a perfect match for server consolidation.

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Comments (3 )

Charles on 28 Nov 2005 at 1:17 am

I do believe that the HP StorageWorks EVA array has similar capabilities as for sharing physical ports with hosts of different operating systems, and each host gets LUN from 0, 1, 2 etc.

An EVA has 4 or 8 physical host ports but can support I think 256 different hosts running HP-UX, VMS, Tru64, Windows, Solaris, AIX, VMware etc.

Pavel Mitskevich on 28 Nov 2005 at 3:49 am

I really like Host Storage Domains because they allow create isolated configuration for each host. But it’s still too complicated to manage and integrate different parts of SAN.

Simple exaple how add server to SAN with the following requrements:
1. 2 independent fabrics.
2. 2 HBAs per host.
3. 1 zone per each initiator/trarget pair.
4. Access to each LUN over all possible ports in Thunder 9570V.
5. Multipathing management withthird party Volume Manager.

Necessary actions (they don’t depend on storage vendor in most cases):
1. Identify WWN of HBA (2 HBAs = 2 times).
2. Bind HBA to fabric (2 HBAs = 2 times).
3. Create zone (4 ports in 9570V = 4 times).
4. Rescan SCSI busses to allow storage to see its HBAs (2 HBAs = 2 times).
5. Create and configure Host Storage Domain parameters (4 ports in 9570V = 4 times).
6. Create and format LUN (once per LUN).
7. Allow access to LUNs (4 ports in 9570V = 4 times).
8. Rescan SCSI buss to configure LUNs (2 HBAs = 2 times).
9. Write OS label to disk (once per LUN).
10. Configure disks with third party Volume Manager to utilize multipathing (once per LUN).

What is HDS vision to minimize number of tasks and simplify this process? How do you plan to develope HiCommand tools?

MikeT on 02 Dec 2005 at 11:50 am

Host Storage Domains is not a competitive differentiator in this day and age. Most disk arrays these days allow provisioning of LUNs over the same Physical Target port for multiple Operating systems each of which can have its own address space. You can have multiple LUNs with LUN ID 0 if you want to on the same Target Port for different initiators residing on different servers and different Operating Systems. The EVA has this capability, so do the Engenio boxes so does Netapp.

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