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Object-based storage and ATA disks are perhaps the most intriguing of the new storage technologies emerging from the convergence of network-attached storage and storage area networks. But both concepts are rife with problems that still need to be overcome.
Object storage refers to data tracked with attributes and metadata, instead of with a file system, while ATA drives are increasingly being used by top-tier array makers because of their low cost compared with traditional SCSI or Fibre Channel drives.
EMC Corp.s Centera hardware is currently the only product being sold with object-based storage software, and, coincidentally, one of the few using ATA drives. But concerns about compatibility with third-party software have generated anxiety. Centera is tailored for data thats often read but rarely written to. EMC, of Hopkinton, Mass., is building another Centera-like product, due at midyear, sources said.
The upcoming EMC product will be similar to Network Appliance Inc.s NearStore and Storage Technology Corp.s BladeStore storage devices, which use ATA disks but not objects for the opposite function: to store data thats rarely read but frequently written to for archiving.
Among issues facing object storage, the most basic one is that current applications, networks and storage management software are designed to work with files and blocks, not objects.
“The architectures have not yet been reconciled,” said Michael Mesnier, storage architect at Intel Corp., in Santa Clara, Calif., and co-chairman of the Storage Networking Industry Associations Object-based Storage Device Technical Working Group. “Weve got just about every major vendor working with us, working to the closest thing we can get to a standard.” A standard is hoped for this year, and a time frame will be set this week at the SNIA Symposium, also in Santa Clara, Mesnier said.
In the object storage model, high-level pointers are stored in metadata servers, which mediate between the object storage device and an application requesting data. As a result, third-party developers must modify or rebuild their basic product architectures, rather than perform the typical platform port. Security, disk attributes, transaction semantics, object naming and recovery are all issues still being discussed, Mesnier said.
In addition to those issues, which affect how future object storage will be built, partners of vendors such as EMC, which has developed its object storage devices independently, face other problems. For example, Legato Systems Inc. is having problems connecting its flagship Networker backup software to Centera APIs, said George Symons, vice president of product management and development at Legato, in Mountain View, Calif. There are also concerns around Centeras slowness in assigning a unique name to each piece of data, Symons said.
More than 40 partners successfully integrated legacy software with Centera, EMC officials said. Symons blamed some of Legatos problems on underestimating Centeras complexity. But Legatos concerns are not isolated. Scientific Software Inc. completed the integration of its laboratory, knowledge management and records compliance software with Centera but found it difficult to track objects once they were created, said officials at the Pleasanton, Calif., company. Sometimes, objects are deleted but their identifiers remain, and those identifiers can clog system resources, thus making the Centera hardware and third-party software bundle seem slow to users, officials said.
Veritas Software Corp., also of Mountain View, and another significant California-based data management company that asked not to be identified havent decided if object storage systems such as Centera are worth porting to, a Veritas spokeswoman said.
Meanwhile, ATA disk systems have problems related to reliability and speed, and so far, enterprise storage companies target the technology only for low-end purposes. But experts predict that storage companies will use smart software to compensate for ATAs shortcomings.
ATA drive makers such as Maxtor Corp. are working to develop SCSI-level reliability by giving more control over how error corrections are done to OEM partners, said Maxtors product manager, Robert Wise. The Milpitas, Calif., company is also considering adding mode page control to ATA drives, which is a standard SCSI feature.
After five months using EMCs Centera box, Bob Terdeman said hes pleased with the product, which he uses with Documentum Inc. software. “With the capacity for 5 million medical documents, Im able to replicate my entire business to a remote site,” said Terdeman, chief technology officer of Rogers Medical Intelligence Solutions, a unit of Rogers Communications Inc.
But Terdeman said hes not giving up EMCs Clariion storage array, in which he stores his mission-critical and real-time data, as Centeras object technology is new and somewhat unproven.
“Ive watched technology come and go. Its always the same questions: Is it prudent to adopt the technology? What is the company going to do to support the technology?” said Terdeman, in New York.