Saturday, June 25, 2011

Utilizing VMWare Together with your Storage Infrastructure

By Molly Webster



VMWare can be a effective computer software tool that could empower your IT staff to create a much more flexible and resilient environment for business applications. There are a number of rewards to utilizing VMWare together with your SAN, NAS or iSCSI storage infrastructure.

Availability - Shared data storage systems on redundant LAN or SAN Fibre Channel fabrics present the ability for users to make use of tools for example VMWare VMotion and Site Recovery Manager to move, recover and monitor VMs with limited to zero program downtime

Redundancy - Extend multi-pathing to all virtual machines, together with extend failure resistance

Efficiency - Makes load balancing and high availability a lot more affordable by eliminating dedicated standby hardware

Disaster Recovery - Disaster Recovery capabilities are enhanced when bare metal restore limitations are removed because of the VMWare hypervisor

Although you will find numerous rewards of shared storage for VMWare, you will need to figure out when your storage is configured correctly.

Correctly planning the essential storage capacity for an optimized VMWare environment requires appropriate preparing and continuous efficiency tuning. The ultimate objective of performance optimization is discovering and eliminating all probable roadblocks that reduce the full utilization of the Core Four resources (CPU, Network, Memory, and Storage). Here, we will talk about eliminating roadblocks for storage.

Storage Choice

When determining the very best place in your storage infrastructure to deploy your VMWare environment, selecting the appropriate storage array or configuration is one of the most crucial elements. There's often the obvious trade-off between cost and performance and storage should be divided into tiers depending on a number of factors. In the end, each and every application must be supported on the tier best suited for the organization with a balance of price in mind.

Tier 1 - Presents maximum efficiency and availability. This tier may possibly utilize built-in snapshots to facilitate point-in-time restorations and supports replication, full storage processor redundancy, and Fibre Channel, SAS or SSD drive technologies. Smaller, quicker disk will increase performance here. This is a greater price per spindle tier.

Tier 2 - Delivers mid-range efficiency, less availability than high-tier storage, limited storage processor redundancy, and maybe slower, larger Fibre Channel drives.

Tier three - Delivers limited performance and small storage redundancy. This tier needs to be built on high capacity, lower performance SATA drives.

NOTE: Not all VMWare applications or environments have to be in Tier 1., if specific elements call for Tier two or Tier 3 storage (like redundancy or snapshots) there might be alternative approaches for delivery, which incorporate but aren't limited to:

Repurposing / Retrofitting a legacy storage platform Utilizing 10K 146 or 300GB fibre channel drives in leui of SATA drives Swapping SATA for fibre channel drives De-installed brand named storage arrays and storage expansion upgrades

Disk Drives: Fibre vs. Sata vs. SSD vs. SAS

Assessing the correct tier for numerous applications can be a essential step that can not be skipped. When determining which application to run on high-performance disks and which ones to save for SATA-based tiers, it might help to ask your self several questions 1st.

How essential is the VMWare environment to your organization? What are the application-specific performance and availability requirements? What are the applications' point-in-time (PiT) restoration requirements? What sort of backup requirements does this application have? Do I have to replicate this application's information?

A lot of storage managers often find themselves deploying SATA technologies for VMWare infrastructure, only to find themselves resource constrained with 6 months. When taking into consideration the kind of disk drive to deploy, think about the long term requirements for the environment.

Effectively Configuring the Storage Array

Storage array design will require storage managers to map the defined storage requirements to the resources of the storage array utilizing these guidelines:

Every single RAID group supplies a specific tiers of I/O efficiency, redundancy, and capacity. LUNs assigned to certain RAID groups ought to be based on these requirements. By way of example, high performance applications may possibly be assigned to LUNS with RAID ten configurations to boost I/O and spindle count

Don't skimp: If a certain RAID group is unable to ensure the needed I/O efficiency, capacity, and appropriate response times, you should define an additional RAID group for the next set of LUNs. It truly is imperative that you supply sufficient RAID-group resources for each set of LUNs.

The storage arrays ought to distribute the RAID groups across all back-end and internal channels and access paths. This ensures load balancing of all I/O requests to meet certain performance requirements of I/O operations per second and response times.

Peak Period Activity

It's essential to base the style of the SAN around peak-period active and consider the nature of the I/O within those peak periods of time. You may find that additional storage resources and capacity are required to manage sudden spikes.

As an example, a peak period may happen in the course of batch processing or in the course of morning usage spikes when end-users are coming on-line. This might be characterized by numerous peaking I/O sessions requiring twice to three times the average for the entire peak period. Without having additional storage resources to handle peak activity, I/O demands will exceed the capacity of a storage array and could lead to delayed response times.

Unique Requirements for High Availability

Production systems should be developed to eliminate all single points of failure. Make sure that redundancy is built into the storage design at all levels of the virtualized platform. Be sure that you create in extra switches, HBAs and HBA channels, and storage processors that create efficient and redundant access paths to your data.

This could be accomplished in several ways:

Redundant Storage Components - Redundant SAN hardware like HBAS, switches and directors and access ports are essential for full redundancy. In certain instances, a redundant storage array could be part of the style

Redundant I/O Paths - Paths from the host or server to the storage array have to be redundant and switchable if a port, device, or cable failure should occur

Mirroring - So that you can get protection against failure of an entire LUN, mirroring could be implemented. Mirroring designates a second LUN created to capture all write operations to the main LUN. LUN mirroring can be either be implemented at the SAN switch, server, or storage array level

Planning for Disaster Recovery

Within the event of a disaster scenario or site failure, it may be needed to recover the failed applications and virtual machine information from a remote web site. A storage array ought to permit access to the information from an alternate server in order to begin the information recovery process. VMWare, as well as VMWare Web site Recovery Manager (SRM), makes this process easier as you do not have to reinstall the OS on a separate physical machine. Administrators can restore the virtual machine image and continue working from that point on.

Performance Tuning: What to Watch

If you have VMWare capacity preparing tools or performance monitoring capabilities, here are several efficiency metrics to watch on your storage array:

I/O Reads I/O Writes Disk Write Queue Length Disk Read Queue Length Average Disk Sector Transfer Time I/O Read Bytes I/O Write Bytes

Enhancing Performance

When looking at enhancing performance for virutal machines and your VMWare environment, you can find a number of approaches to enhance speed.

First, make certain the LUN has enough capacity along with the disk utilization is not too high. You might start to expertise degradation at high levels of utilization of volumes and devices (80-90%).

Second, don't just examine adding capacity as a way to increase performance-also contemplate adding much more disk drives. For multi-threaded and I/O intensive applications, more disks typically equates to improved performance. Applications that produce or encounter random read/write sort of workloads typically require quite a few disks to scale.

Lastly, RAID 10 can supply about 50% greater throughput than RAID 5 for random write-intensive environments.

Overcoming Budget Limitations

Frequently, increasing spindle count so that you can boost performance might be high-priced. As a way to meet the I/O requirements and set proper RAID levels, creative methods should be employed to be able to beat the cost/performance trade-off.

Utilizing Used Disk: Leveraging both new and used disk drives can decrease the price of upgrading your storage environment by as a lot as 60%, permitting you to boost spindle count, produce redundancy, or stand up a second array in order to support high availability applications

Repurposing Legacy Equipment: Third party suppliers offers hardware, upgrades, and maintenance for legacy EMC, IBM, NetApp, and Hitachi storage systems enabling consumers to upgrade and repurpose legacy equipment as a way to produce redundancy for Tier 1, 2 or 3 applications, support development and test environments, or afford additional backup capacity for faster point-in-time restores.

Trade-In/Trade-Up: Find new life in old equipment, and discover new ways to meet your performance and capacity requirements. Upgrade the storage network, add larger quicker disk drives or trade in your 2Gbps storage array for a 4Gbps or 8Gbps model.




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