Virtual storage strategies.
Storage virtualization is the concept of creating 'virtual storage pools' out of discrete physical storage elements. The concept isn't new but will slowly shift mainstream in India. In a way, storage visualization has existed for a long time in the form of volume management. A volume manager was a piece of server software that allowed the OS of that specific host to have a logical view of a physical device.
For example, when many OSs had a file system that could deal only with a maximum device size of 2 GB, the volume manager would enable a 10 GB disk to appear as five 2 GB logical disks, and therefore make the disk usable. The second wave of storage virtualization occurred in the disk army itself. Large arrays utilized internal virtualization to make the array usable among multiple hosts. This was necessary because volume managers work well for single hosts, but not when there is more than one attached to a single device.
The new concept of storage virtualization is the externalization of virtualization from both the hosts and the storage a virtualisation engine that resides somewhere in the storage 'cloud.' This is required because just like we needed device-based virtualization to deal with multiple hosts, we need externalised cloud-based virtualisation to deal with multiple storage devices and multiple hosts.
In and out schemas
The external virtualization schemes, sometimes called SAN appliances fit into two main categories. They are In-Band and Out-of-Band. In-Band virtualization engines run on some kind of hardware which may be a specialized box or an off-the-shelf PC. In both cases, the data running between the host server and the storage itself runs through this engine.
The engine takes all the physical storage behind it and presents it in the way a user wants to use the servers on the network. The benefit of an In-Band approach is that there is no host software required. A potential negative effect of this approach is that In-Band runs the risk of becoming a bottleneck at some point.
Out-of-Band visualization engines sit on a special box that connects to the storage network but isn't in the data path. This approach offers no scale limitations but does require special host software/drivers that may either be software or firmware embedded in a special HBA (Host Bus Adapter).
Analysts at the Meta Group say that during 2003-2004 storage visualization will enable the ability to allocate storage regardless of physical storage frames. Not only will there be technical challenges, but it will also make enterprise storage procurement and usage-based software licensing more complex. Vendors with robust software, experience, and proven financing programs will succeed in this environment. IT organizations should pay particular attention to virtualization clauses within initial contracts that stipulate alternatives.
Meta Group also says visualization is a good first step to enterprise storage management but it will not be a universal remedy. IT organizations must evaluate more than storage allocation to servers to satisfy and create a robust enterprise storage infrastructure.
Cost of storage solutions
It's difficult to provide estimates of network storage solutions because it depends on various factors like size, scalability, company locations, and growth. The factors will also vary between different companies and industry verticals.
M. Ganesh, Country Executive, ESG, at IBM India says, "Enterprises should evaluate storage needs on criteria like organizational objectives, current storage infrastructure, and the ways in which the solution can provide value to the organization.
It's important to realize that price alone should not determine the buying decision. A solution should be based on open standards to avoid getting tied to a single vendor. Companies should ask for independent benchmarks for assessing performance and service levels."
Sathyan Gopalan, National Manager, Storage Solutions at Computer Associates says, "At an entry level a company may want to migrate from a scenario of individual tape devices on each server to a centralized environment using a tape library and automated backup software.
Depending on the scale of the environment, which depends on factors like the capacity of servers, need for online database backups, and size of data, the investment budget can be between Rs 20 Lakhs to 40 Lakhs. NAS and SAN installations could cost much more."
Binod Kumar Panda, Country Manager of Apara Enterprise Solutions gives indicative pricing for a 500 GB storage sub-system. "The price of a low-end NAS disk subsystem starts at around Rs 7 Lakhs. Backup software and Tape Libraries will cost between Rs 8 and 11 Lakhs. So an average solution will cost between Rs 15 and 19 Lakhs.
Now if you need to replicate the data it will cost almost 1.6 times or double that of the primary set-up (disk sub-system). For higher capacities the prices will go up accordingly," says Panda.
SSP--My place or yours
A SSP (Storage Service Provider) can be a third party who manages the storage facilities for an enterprise. The storage devices can be on the customer's premises or at the SSP's site connected to the customer's machines through high bandwidth links. SSPs provide customers an alternative to buying their own computing infrastructure and managing it themselves. Most SSPs offer capacity in huge RAID farms and primarily target enterprises with big, mainly Internet-related, storage needs.
Nikhil Madan, Country Manager, Legato Systems India says, "The SSP has the responsibility to manage and protect your data. It can provide you a solution which will scale along with enterprise growth. Enterprises can benefit from the reduction in TCO of storage infrastructure that an SSP will allow." It's a big opportunity for existing data centers to embrace a SSP model since most of the required technical infrastructure is already in place.
The SSP market is now one of the most analyzed segments in the storage industry. According to IDC, worldwide spending in this market will increase at a staggering CAGR (Compound Annual Growth Rate) of 134 percent, from $153 million in 2000 to $10.7 billion in 2005. Despite this growth, IDC warns players in this space must use caution to avoid pitfalls.
Doug Chandler, Manager for IDC's Storage and Data Management Services program says, "SSPS must demonstrate their viability to potential and current investors and concentrate on market validation. It will be critical to the market that the SSP model becomes more widely accepted by paying customers, regardless of which SSPs become market leaders."
IDC believes that the SSP market is in a state of flux, bulleted by shifts in customer wants and needs, investor tendencies, technology supplier strategies, new and untested technologies, and the continuing primacy of the Internet in driving industry development.
"The success of the SSP market will be closely tied to the success of the Internet Data Center, Web hosting, and other firms that, as partners, will drive much of the storage-on-demand business in the next 12 to 24 months," Chandler said. Aside from economic issues, IDC believes other pitfalls confront SSP players. Data sensitivity is one of them.
"Customers want to outsource many of the mundane details of storage strategy, implementation, and management, yet they don't want to turn over their data. This paradoxical behavior could hamper many SSPS," Chandler said.
To this extent, IDC believes SSPs must offer undeniably clear advantage regarding efficiency, performance, availability, security, cost savings and time to market. Storage pricing guideline and Template Meta Group has devised a storage pricing and guideline template that you can use for a start. Here are the details. To compare multiple vendors' offerings we recommend a strategy that enables organizations to compare 'apples to apples'. Since different storage vendors offer different RAID levels like IBM RAID 5 and EMC typically RAID 1, usable storage does not yield an accurate price/MB comparison. Therefore raw storage evaluations should be used (also consider value-add functionality that may require additional raw storage, but deliver increased application/DBMS or business benefits). Furthermore, the storage procurement should be broken down into multiple categories.
Hardware--RAID controllers, all disk drives, cache, and channel connections into the storage subsystem.
Software--Any and all sottware that is specific to the storage subsystem including SAN management software.
Storage networking components--For example FC switches including cabling and port cards.
Maintenance--Hardware if applicable and all software components with defined warranty periods.
Professional services--With a well-defined statement of work.
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|Title Annotation:||The Virtual World|
|Author:||Das Gupta, Soutiman|
|Publication:||Database and Network Journal|
|Date:||Dec 1, 2004|
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