storage virtualization unleashed

Storage Virtualization UnleashedJames PricePrinciple Fairway Consulting Group, Inc.

Jeffrey SlappPrincipleFairway Consulting Group, Inc.

Session Overview

What is Storage Virtualization? Specifically, its role as it relates to the VMware product line

Advantages of Storage VirtualizationHardware independence, increased storage utilization, investmentprotection, etc….

VMware ESX under a Storage Virtualization architectureSpecifics relating to VMware ESX deployments

Best practices in Virtual EnvironmentsNotes from the field and customer deployments

Q & A

What is Storage Virtualization?

What do we mean when we say “Storage Virtualization”?Storage Virtualization is a concept of storage impersonation. This impersonation takes the form of a virtual disk LUN presented to the virtual server host. The virtual disk LUN is simply an abstraction of the real physical storage being managed by the virtualization controller (Storage Domain Server – SDS).On the client (target) side of the SDS, the SDS presents the virtual disk LUN to the virtual server host (initiator). The virtual disk LUN can be any size up to 2.0 TB (upper limit per LUN on most OS’s)

On the storage (initiator) side of the SDS, the SDS consumes thestorage presented by the storage devices (targets) and aggregates this storage into a unified pool.

What is Storage Virtualization?

Here is a basic storage configuration diagram:

Fabric

The VM Hosts are zoned on the fabric with the target side of the Storage Domain Server(s) only.

The storage enclosures are zoned on the fabric with the initiator side of the Storage Domain Server(s) only.

Initiator

Target

Initiator

Target

Target

Target

Target

The SDS presents itself as an initiator/target device simultaneously on the fabric.

Advantages of Storage Virtualization

Major Advantages of Storage VirtualizationHardware Independence• The SDS software can run on any commodity-based hardware

platform that supports Windows 2000 and higher. This feature gives the administrator a huge selection of chassis to choose from.

Heterogeneous Storage Devices• The SDS is a very specialized software package that runs on a

Windows platform, therefore any storage device that appears in the Logical Disk Manager can be utilized in the storage pool. This feature gives the administrator a huge selection of storage devices to choose from.


Major Advantages of Storage Virtualization (continued….)Simplifies System Administration• The SDS’s present virtual LUNs in up to 2TB in size. For the large

majority of storage scenarios, this virtual size will not be fully utilized by the application server (VM Hosts), so therefore having to extend a volume is no longer an issue.


Major Advantages of Storage Virtualization (continued….)Advanced SAN features• Auto Provisioning – Auto provisioning is responsible for auto-allocating the

128MB blocks on the backend storage devices. As data is written out to the virtual LUN, the SDS automatically allocates the space on the physical disks.

• Auto Failover – All SDS mirror partners may actively process I/Os with one handling primary paths for some of the volumes and secondary paths for others. In the event of a failure, the remaining SDS’s take over with the mirrored volumes. Application servers must be adequately configured with qualified multi-path drivers to take advantage of this automatic failover feature.

• Snapshot – Point-in-time snapshots are generated using copy-on-write technology for selected virtual volumes.

• High Availability (Synchronous mirroring) – Synchronous mirroring duplicates all write I/O to the companion SDS. This provides redundancy in the event of failure. All virtual LUNs are available down all paths for read/write I/O simultaneously from both SDSs.

• Asynchronous IP Mirroring – The Asynchronous IP Mirroring (AIM) option replicates selected volumes between a pair of SDS’s using native IP connections over long distances.


Major Advantages of Storage Virtualization (continued….)Drastically Higher Storage Volume Utilization• The SDS’s use a very optimized and efficient method of de-staging

data from cache to the backend storage devices. The result is a much better utilization of your storage (typical utilization is between 85-90% of physical storage).

128MB 128MB 128MB 128MB

Physical Storage

128MB 128MB 128MB 128MB

128MB 128MB 128MB 128MB

128MB 128MB 128MB 128MB

128MB 128MB 128MB 128MB

Unallocated Storage

Fabric

DATA


Major Advantages of Storage Virtualization (continued….)High Performance Caching System• Inside an SDS, 80% of the available system memory is converted to cache

memory. Most typical implementations use chassis’s with 4GB of total system RAM, leaving 3.2GB of RAM dedicated to I/O cache. The amount of cache is only limited by the amount of RAM in the SDS.

Simplified Storage Proliferation • When the backend physical storage utilization reaches 85% (by default), the

SDS’s notify the administrator that more storage should be added to the pool. The administrator only needs to connect more storage to the fabric (or to the SDS in a non-fabric environment) and add it to the managed storage pool on the SDS. Once the storage has been added to the pool, it is immediately available by the application servers (VM Hosts).

Unmatched Storage System Redundancy• SDS redundancy can be as small at two and as many as eight. The

redundancy is also very flexible, so the storage system can grow as your business grows.

VMware ESX Under a Storage Virtualization Architecture

VMware ESX is not treated any differently than another other application server connected to the SDS with regards to I/O and storage allocation.The only instance where the SDS responds differently to ESX specifically is under an HA (high availability) configuration. The native ESX MPIO driver understands “light on” or “light off” with respect to a storage target. In the event of a backend storage failure, the SDS will initiate an ESX host path failover by turning the laser off on the HBA. This will indirectly tell ESX that it should immediately failover to the other path and resume I/O.

Best Practices in Virtual Environments

(work in progress…..)Notes from the field as it relates to VMware ESX in a High Availability configuration.


(work in progress…..)Notes from the field as it relates to VMware ESX in a High Availability configuration with Asynchronous IP Mirroring.

SDS

Server 1 Server 2 Server N

Fiber Channel Switch Fabric

SDS

ISL Trunk

SDS


(work in progress…..)RDMs vs. VMDKs

Discussion about when to use RDMs and when VMDKs may be more appropriate. The discussion will surround these two types of disk modes as they relate to leveraging the Virtual SAN advanced feature sets.

Sizing VMFS on a Virtual SANVirtual LUN sizes with regards to VMFS recommendations.

Thank you

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