Recently Wikibon met with Ping Ooi, an IT practitioner at Ares Management, a financial services firm based in Los Angeles with operations in New York City and London. Ares is a roughly 75TB shop running 152 servers (101 virtual). Its primary apps are Exchange, test/dev/QA, and specific systems focused on financial services (e.g. portfolio management). The company's storage is 100% supplied by Compellent.
What we learned:
- Ares has 1/2 FTE managing 75TB's worldwide. Ooi believes it would need 3-4X this figure using traditional storage on a SAN.
- Ares uses a three-tier storage strategy with 15K FC, 10K FC, and SATA drives.
- The use of Compellent's Data Progression software (automated tiered storage) has allowed Ares to move most data to SATA but maintain necessary performance. The alternative strategy of using DAS or traditional array-based storage would have meant Ares would have had to configure storage for peak performance and it wouldn't have been able to migrate data to lower cost devices dynamically. Ares believes it has saved at least 40% in terms of acquisition costs based on this feature.
- Perhaps the most innovative use of Compellent's technology by Ares was to introduce a disaster recovery strategy with very low RPO (meaning that very little data is lost in the case of a disaster). The way Ares implements this is via a replication strategy that copies data to Compellent's Portable Volume, a group of disk drives that can be placed in a case and shipped to a remote site. Once a snapshot is placed on the Portable Volume, Compellent software is smart enough to replicate the delta changes to the DR site while the Portable Volume is being physically shipped to that site. Compellent software understands the state of the data saved on the portable device, relative to the delta changes, so that when the Portable Volume is plugged into the DR site, Compellent software synchronizes the delta changes with the portable volume to provide an up-to-date copy.
If a disaster had occurred at the original site during this process (worst case) the only data lost would be the in-flight data changes-- i.e. minutes worth of data. Once the Portable Volume arrives to the DR site, Compellent software can re-create the data meaning RTO is within hours of arrival at the site.
In theory this can be done with tapes, but the automation Compellent offers makes this approach exceedingly attractive and simple with very little staff involvement. An alternative approach is to replicate over high-speed lines, but this approach has a much higher amount of lost data in the case of a disaster. Also, high-speed lines across the country and over the Atlantic are prohibitively expensive, and Compellent's approach is sensible from an economic standpoint. The fact remains that trucks and planes continue to be more cost-effective than high-speed communications lines for transferring bulk data.
Tier 1.5 arrays such as those offered by Compellent stress ease-of-use, simplicity, heavy use of virtualization, and dynamic migration to enable the exploitation of low-cost SATA devices. They also bring high degrees of automation. The tradeoff is users can't tune LUNs and optimize performance, the array does that automatically. Most shops perceive this as a big benefit; however a "LUN-master" might take exception.
Action Item: Organizations that require low RPO and can deal with RTO's of many hours should evaluate Compellent's Portable Volume as a technique to provide minimal data loss with maximum automation. This approach is cost effective for environments that don't require zero data loss and RTO's of a few hours or less.