Serial SCSI, ATA Drives to Mix With Each Other

Computerworld - Analysts and storage vendors said one of the key benefits of the serial SCSI interface technology that's due to start being built into disk drives this year is its compatibility with the Serial Advanced Technology Attachment (ATA) interface used in low-end drives.
That will enable the development of hybrid storage arrays that let users mix and match high-performance SCSI drives for use in transaction processing applications with lower-cost Serial ATA devices for data backup and recovery procedures. The two disk-drive technologies could also be plugged into a single backplane within servers, according to drive vendors.
Serial ATA drives are mainly used in desktop systems now but are finding their way into disk arrays that store fixed data or provide nearline storage capabilities. With the advent of serial SCSI, a company could configure arrays to store transactional data on disks equipped with that interface while putting check images or financial documents on Serial ATA drives, said John Joseph, vice president of marketing for the server products group at Maxtor Corp. in Milpitas, Calif.
The transactional data could also be mirrored to Serial ATA drives for backup purposes prior to being archived on tape devices for long-term storage, Joseph added.
The average per-megabyte costs are 1 to 2 cents for Serial ATA disks, 3 to 5 cents for existing SCSI devices, and 7 to 15 cents for Fibre Channel drives that are typically used in high-end arrays, according to IDC in Framingham, Mass.
IDC analyst Robert Grey said the ability to mix serial SCSI and ATA drives in servers and arrays has the potential to lower total costs of ownership for corporate users while also letting them customize storage setup to meet their needs.
If systems are designed with Serial ATA drives but include disk controllers that can also support serial SCSI, adding the higher-performance drives "is a simple, seamless upgrade," Grey said. "Users can make a move to a more robust drive in terms of availability and performance if they want to."

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