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Users struggle to get tiered storage right

MGM Mirage and the Chicago Mercantile Exchange have created tiered storage architectures, but found that data classification and deletion policies were hard to nail down.

LAS VEGAS -- Re-architecting tiered storage was the theme of the day at Storage Decisions, Wednesday, as users listened to presentations from two large companies grappling with the challenge of tiering storage.

Hotel and gaming giant, MGM Mirage has 180 terabytes (TB) of storage split evenly between Tier-1 and Tier-2 disk and 4 petabytes of data on tape. With 70,000 employees, 24 properties and 285 IT applications, this company had a lot to consider in designing its storage architecture.

"It wasn't about the most important data on the most expensive storage and least important data on the least expensive storage, that's not the situation we ended up in," said Laura Fucci, vice president and chief technology officer of MGM Mirage. "It was more about this type of storage works in this fashion and is better for random I/O applications, and Tier-2 storage is better for applications that do not deal with I/O variance, but require high capacity."

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MGM implemented EMC DMX systems for Tier-1 storage and Clariion arrays for Tier-2. It's now taking steps toward classifying its data and has divided its applications into three tiers. Critical data, which is anything that affects guest services, must be replicated in real time. Enterprise data, which is the company's internal applications like finance and human resources, is afforded snapshot technology and finally, support data, like the company's spa system is archived.

The next step, which caused MGM the biggest headache, was figuring out how long to keep everything. "We circled around for a year on our document retention policy," Fucci said. "People were more focused on how to enforce [policies] than how to establish them." Now the lawyers are involved and this is getting done, she said. "I expect to have a schedule in January as far as what different documents there are that we need to maintain … On the technology side we are ready."

MGM picked Veritas Software Inc's Enterprise Vault for e-mail archiving, which it plans to run on NAS. Enterprise Vault has a single instance storage feature that will help the company to reduce its capacity costs, Fucci said. It's also bringing in EMC Centera to archive its FileNet data and for write once, read many compliance.

"Our data keeps growing, I'm not sure we are getting ahead of it, we are just trying to keep up," Fucci said.

Chicago Mercantile Exchange redesigns its tiered storage

Meanwhile, the Chicago Mercantile Exchange (CME), which manages 200 TB, started out with five tiers of storage that associate director of open systems, Craig Taylor, admits "was a nightmare to manage."

The only tier the company has not changed in recent months is Tier-1, which houses all CME's high-performance data associated with trading and lives on EMC DMX arrays.

Tier-2 houses other production data and was on Hitachi Data Systems Inc. 9960s. This is getting "old"' according to Taylor who is looking at Clariion to replace the 9960s.

Tier-3 includes regulation data and lived on Hewlett Packard Co. 2200 MX optical jukeboxes. "This wasn't scalable and when you pull platters out, it's a manual process and [the data] might as well be on paper," Taylor said. CME is replacing the 2200 MXs with EMC Centera, although Taylor is uncertain about this choice. "I have to say I don't like Centera, you're putting the longest term data on a volatile system of Linux servers… The way they are storing data is not good." He added, "We've replaced a couple of units already and are looking for more reliable long-term storage."

Tier-4 houses the company's backup and restore data and lived on standard ATA disk until the company bought in Copan Systems Inc's massive array of idle disks product. Despite the system's ability to power disks on and off when they are not being used, which could cause reliability issues, Taylor said he's been running the system for a year and has not had to change a single disk.

And finally, Tier-5 is archival data, which was on Storage Technology Corp. (StorageTek) Powderhorn libraries but repeated robotic arm failures and StorageTek's lateness to market with new products prompted CME to switch to IBM 3584 libraries for off-site storage. "Plus IBM came to us with a great price," Taylor said.

Tiers are static, not dynamic

Although the company has figured out which data should reside where, it has no policies set up to move data to the appropriate tiers automatically. "We looked at how to move that stuff but the juice wouldn't be worth the squeeze, just leaving it out there seemed to work fine," Taylor said.

Similarly, the New York Stock Exchange has a couple of tiers of storage between EMC DMX and Clariion arrays housing 250 TB in total, but has not implemented what storage consultant Peter Carucci calls "real" tiered storage. "There's no migration from one to the other," he said.

Like MGM Mirage, the Chicago Mercantile Exchange found that the data classification process was the hardest part of building its tiered storage model. "It's hard to determine the value of data as it changes," Taylor said.

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