Our university is planning to install Seagate's Xiotech Magnitude SAN. They utilize the virtualization concept using SCSI drives. Each unit can hold 2 Tera Bytes of data and is based completely on open standard.
We are using Novell with Microsoft application servers for students' e-mail use. Can you provide me with areas of concern regarding virtualization? What do you foresee as the problem areas? Your comments will be much appreciated. Thank you.
That solution should work fine for you although I do not consider it a "carrier" grade solution.
Virtualization to storage provided through an appliance works great for connecting diverse storage vendors into a pool of storage. This provides investment protection for older or cheaper disk arrays to be used as part of your SAN. The only problem I see with this type of approach is scaling. Putting too much storage behind a server running virtualization software can become a bottleneck at some point. Direct fabric connection to a raid array makes more sense for high performance and "real-time" type database applications. In order to virtualize at this enterprise level the virtualization method used needs to be transparent to the data stream. Using a global file system or "metadata" approach that controls access and is "out-of-band" to the data stream is more scalable and usable at the enterprise level.
SNIA is working on this with all the storage vendors to provide an open standard on virtualization methods at the "FABRIC" level. Using IP for metadata access may help move the control information out of the data stream, and provide an open method for all vendors to provide virtualization. This will require either smart HBAs, smarter operating systems or appliances that provide the metadata access. This means cooperation between operating system vendors may be needed to truly make it an open standard and that may be a little ways off in the future. Until that happens there will be many startups adding their own implementations to the in-band method.
There are other software only solutions that just require a generic NT server or Linux server to run the virtualization engine to pool either Fibre or SCSI connected disks. This may be a cheaper route to use if budget is an issue.
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This was first published in February 2002