Managing SAN Space Doesn’t Require a Miracle Cure

- by Elizabeth M. Ferrarini

Dr. William J. Mayo - “The best interest of the patient is the only interest to be considered.”
Mayo Clinic’s Research Department didn’t wish for a medical cure for managing space on a 1.4-Tbyte storage area network (SAN) predicted to hit 4 Tbytes by 2002. The IT department listened to researchers’ requests, and, in turn, empowered them with the tools and the education on how to manage their storage space. The IT department can accurately time and budget for additional storage devices.
Based in Rochester, Minnesota, Mayo Clinic’s Research Department comprises about 3,900 professionals, including staff doctors, scientists, and other health professionals, in 53 departments. These professionals work on $240 million in annual funded projects that cover every aspect of medicine - from designing infectious-free transplant organs to preventing rheumatoid arthritis. Researchers have developed patented software tools for navigating around 3D images.
The Research Computing Facility (RCF) provides the heterogeneous IT infrastructure to support laboratories managed by 240 principal investigators. Overall, data moves from collection to analysis across all server platforms in many formats. For example, a researcher may use a Sun server to collect data, then analyze it in 3D on an SGI workstation, and put the results in a Windows NT PowerPoint presentation.
Explosive data growth over the past three years has made it inefficient for researchers to access and to store large imaging files, databases, and Web documents, on disparate LAN-based servers. Paul Bleimeyer, RCF’s Windows NT administrator, says, “The management board felt it was more cost effective to build a SAN than to keep buying and managing new servers just to have more storage.”
From any server-based workstation, researchers now can easily access all of their data safely stored on the SAN.
The SAN front-end consists of eight Windows NT servers. Using Brocade switches and fibre channel interconnects, these servers plug directly into the SAN’s Dell PowerVault 650 RAID 5 storage system, which interconnects with four Dell PowerVault 630 JBOD’s. Total current storage comes to 1.4 Tbytes.
The NFS interface, which is used by workstations and the SAN servers, enables the non-Windows NT workstations to mount their home directories and department directories automatically on the Windows NT SAN servers. In turn, these workstations enable researchers directly to access and store their data on the SAN. The NFS-mounted disk directories appear as local storage to these workstations.
To distribute SAN space fairly to everyone, the RCF turned to disk quota management and reporting. It allocates a space quota, sends alerts as the quota gets reached, and requires employees to groom space to stay within the quota. Bleimeyer says, “Carrying out quota management requires a good partnership with management teams and good communications with employers. Our researchers understand why they’re allotted a certain amount of space on a 200-Gbyte partition.”
Prior to the SAN, the Research Dept. had tried quota management. Bleimeyersays, “Researchers complained that the product didn’t provide enough alerts.”
For the new product, researchers told Bleimeyer they wanted more detailed alerts for their quota, and reports that simplified their file grooming. He selected StorageCentral, a Windows NT-based product from W. Quinn Associates Inc., Reston, Virginia.
Bleimeyer says that how StorageCentral would be carried out became the topic of general laboratory meetings, e-mail messages, and several newsletters.
The RCF assigned quotas according to the predicted storage needs of each researcher and each department. For example, some researchers have a 200-Mbyte quota on their home directories, while others, up to 2-Gbytes. A quota on a department’s folders can range from a half Gbyte to 50 Gbytes.
Researchers receive about three personalized e-mail message alerts as they reach certain percentages of their quota. The message says how much space they’ve used and how much to free up. He says, “StorageCentral doesn’t care what e-mail programs the system uses.”
Researchers routinely receive a HTML-based report via e-mail showing a snapshot of their storage space. He says, “This report helps researchers to identify the rate at which they’re consuming space.” Upon request, Bleimeyer says he’ll give them more detailed HTML-based reports. The report’s hyperlinked file listings enable researchers to call up files instantaneously.
Bleimeyer says, “Researchers can use the reports to determine what to move onto a CD ROM, DVD, or ZIP drive in order to free up space. They also know if they require more space to create images for a conference. This capability puts data management back into their hands.”
“We also can send copies of message alerts and reports to both the principal investigator and the lab coordinators. We can also tailor the alert message and the content of a specific report.”
Reports, such as duplicate files, files not accessed by specific dates, and partition summary, also have helped the RCF to take control of overall SAN space.
Because NFS makes all the storage appear the same to all workstations, each front-end SAN server must perform at the same level. He says, “Once you crack the 80 percent disk usage mark, performance problems arise. Quota management has kept us within that mark by allowing us to watch how quickly certain partitions fill up.”
When it came to planning for additional SAN storage, Bleimeyer collected data based on how much space researchers and departments had consumed of their quota. He compared this data with storage projections from management committees and arrived at the amount of storage for the next few years. He also got the approval to add a tape library to the SAN.
The Research Dept.’s SAN is still evolving. Bleimeyer says, “Quota management has alerted us to the need for file migration, which is being done manually now.”
Quota management on the SAN enables the the Research Dept. to have a finger on the pulse of its storage at all times, and not on its pocketbook. Bleimeyer says, “The calibre of employees makes a difference in carrying out quota management.”

Elizabeth M. Ferrarini writes free lance about technology. Based in Boston, Massachusetts, Ferrarini is the author of two books about online services.

«BACK to the Articles Index