A NEW BACKUP PLAN
Federal Computer Week, September 2001 | Written by John Zyskowski
|
A NEW BACKUP PLAN Federal Computer Week, September 2001 | Written by John Zyskowski |
|
In an ideal world, all federal data center managers
would be able to back up their disk storage systems to secondary disks,
which allow for faster, more flexible data restoration than the tape-based
backup systems typically used. But the disk systems
are several times more expensive than equivalent-capacity tape systems, so at most agencies, it's tape or nothing. But a new class of enterprise disk systems might spur federal information
technology managers to rethink the cost equations behind those long-standing
assumptions. Using arrays of inexpensive Advanced Technology Attachment
(ATA) hard drives, The ATA disk arrays include many of the fault-tolerant features associated
with highend storage, such as hot-swappable disks that can be replaced
without bringing the system down and data protection through Redundant
Array of Independent Disks Backing up to disk instead of tape "gives customers the chance
to change their backup paradigm and get better performance and data
protection at a really cheap price, which is where ATA comes in,"
said Tony Prigmore, senior analyst with Due to its low cost per megabyte, tape has long been the medium of choice for the two main backup applications: quick system restoration and long-term archiving. ATA vendors say system restoration is where their products will provide the greatest benefits. "The advantage of disk-based backup is that disk has a faster retrieval rate than tape," said Dave Hill, research director for storage and storage management at the Aberdeen Group Inc. "Also, disks store randomly, so they can retrieve specific files quicker than tape, which stores data sequentially." Diamond Lauffin, senior executive vice president at Nexsan, claims that the total cost of his company's ATAbased InfiniSAN D2D, or disk-to-disk, backup solution is actually less than a comparable solution using an automated tape library. For example, Lauffin said Nexsan's eight-drive ATAboy RAID array, which comes with the D2D backup software and can store up to 560G of data, costs $8,500. On the other hand, he said that a 12-tape library with two drives and about 600G of storage capacity might cost around $14,000, which doesn't include the several thousand dollars extra for backup software. Costly Archives For now, ATA arrays don't make as compelling a cost case for storing large amounts of data for archival purposes, according to Dan Tanner, a senior analyst at the Aberdeen Group. In that application, data backups are stored on the least expensive, removable media, such as tape cartridges, and then placed in a safe, off-site location. The tapes can be retrieved if a disaster such as a flood or fire destroys the primary data center; quick system restorations are not the highest priority. Nonetheless, Tanner thinks ATA arrays might even gain some ground in that area. "ATA is inexpensive, so you can start to think about removable disks," he said. "And with [the new] Serial ATA disks coming, it will be very easy to have removable disks that are nondisruptive." (See "Serial solution," above.) ATA array vendors currently use custom software to give their products a hot-swappable disk capability. That's a good example of the work they have done to build disk arrays using a technology originally developed to connect one or two hard disks to the motherboard inside a personal computer. ATA has been around in one form or another for about 15 years and is also known as IDE, or Integrated Drive Electronics, because the controller is integrated right on to the disk drive itself. The vast majority of disk drives manufactured each year are ATA, according to market researcher IDC. ATA arrays are currently available only from a handful of smaller disk-storage vendors. But Prigmore thinks that "once these early adopters gain traction, there's no reason why the big guys won't make the same shift" and begin to offer ATA arrays as well. That may be the case, but at least one large storage vendor suggests otherwise. A spokesperson for Dell Computer Corp.'s storage division said the company doesn't have any plans to build ATA-based storage systems. Kevin Connors, senior director of product marketing for 3ware, thinks the large storage companies will not rush to offer ATA for the same reason they have not offered it to date: It's just not profitable enough. "It's very difficult [for manufacturers] to design a product that reduces their [average selling price] and margin contribution while still maintaining the same level of value," he said. Regarding concerns about reliability and performance, ATA array vendors say that field data for ATA drives show that they are as reliable as SCSI or Fibre Channel drives. As for performance, Prigmore said backup applications don't need the fastest disk speed available, and in any case, the means by which an array's RAID controller moves data across multiple drives mitigates any speed disadvantage among the various disks. But 3ware's Connors said those are the types of concerns that ATA array vendors must overcome to get their message out. "A lot of customers consider the ATA world as the disk drive in the PC that their family uses at home, and that doesn't fit in the enterprise," he said. "We've had a lot of education and evangelism to do in the last year and a half, but it's starting to take hold."
|