QuickSpecs

7
Choose the appropriate
disk technology
for your environment
Serial ATA versus SCSI and fibre
channel disks
SCSI disk technology is the right choice for entry-level
networked storage, as it offers the same advantages that
fibre channel disks provide to large enterprise disk
arrays. In addition, it offers a simple migration path from
storage directly attached to servers (DAS) to a storage
area network (SAN)—a key HP offering explained on the
following page.
Serial ATA (SATA) disks available for HP StorageWorks
MSA arrays provide a much lower cost per megabyte
than SCSI or fibre channel disks. Serial Attached SCSI
(SAS) is the next-generation storage solution for your
enterprise environment. SAS integrates two established
technologies, combining proven utility, reliability and
performance attributes of the SCSI protocol with the
performance advantages of serial architecture. Serial
Attached SCSI allows the customer ultimate configuration
flexibility and simplicity in their storage environments. SAS
solutions accommodate both low cost bulk storage
(ATA) or performance and reliability in mission critical
applications (SCSI). This reduces customer investment
while at the same time increases customer choice and
ease of deployment. Ultimately, customers can buy one
server or storage solution and customize the technology
to fit their unique needs.
SATA is not intended as a replacement technology. SCSI
or fibre channel disks remain a better choice for reliable,
high performance storage. However, if you want cost-
effective storage for infrequently accessed data—such
as data repositories or reference information—then SATA
is perfect.
Tiered storage environments
In a tiered storage environment, you can match your data
to storage that has an appropriate level of performance
and availability—giving you a lower cost of ownership,
without any negative impact on your business. Here’s how
it could work in a typical disk-to-disk-to-tape environment:
• Data with the highest availability and performance
requirements is stored in tier one on SCSI or fibre
channel disks
• The second tier stores infrequently accessed data (e.g.,
disk-to-disk backup copies) on SATA disks
• Tier three comprises tape-based backup copies, or even
archived data on optical storage
FC/SCSI
disk storage
SATA/FATA
disk
storage
Optical
archiving
Tape
storage
Primary storage
Secondary storage Tertiary storage