Samsung MZ-V6E1T0 Uživatelský manuál stáhnout pdf (Strana 4)

SATA (Serial Advanced Technology

Attachment) interfaces dominated

client storage for a generation.

PC chipsets integrated SATA

controllers, 2.5” and smaller

hard drives became ubiquitous,

and point-to-point cabling

made for easy and inexpensive

connections. In enterprises, SAS

(Serial Attached SCSI) interfaces

provided more performance from

dedicated storage controllers and

enhanced cabling.

When SSDs debuted, they

emulated hard drives at first,

borrowing the 2.5” form factor

and SATA interfacing. mSATA

introduced smaller, lighter SSD

modules, but stayed with SATA

for compatibility. As flash memory

and storage controller technology

improved, many SSDs have hit

the SATA throughput ceiling in the

latest revision of the specification.

Actual performance depends on

many implementation factors, but

theoretical bandwidth limits per

direction are easy to compare.

At first glance, SAS looks like

it might be attractive for SSDs,

especially with support for multiple

initiators and longer cable lengths

(10m compared to 1m for SATA).

However, economics do not favor

SAS for client devices. Typically,

client PCs need a dedicated SAS

host bridge adapter, or servers

use a high-end chipset with an

integrated SAS controller.

Faster is better. After intensive

debate, the SATA community

decided further speed

enhancements were extremely

challenging. In smaller systems

with affordable chipsets and single

or dual drives, SAS tends toward

cost prohibitive. An easier path to

speed is to embrace an interface

that offers better performance,

scales better, and comes

integrated in every new PC chipset

– PCIe.

PCIe has been supported in PC

chipsets for some time, used

primarily for add-in graphics

adapters, networking interfaces,

and RAID controllers. As PCIe-

enabled SSDs appeared, Intel

(who also supplies SSDs) began

focusing on PCIe storage support

in the Intel Series 9 chipset. AMD

and others quickly followed suit.

With chipset support and the

M.2 specification in place,

PC motherboard manufacturers

are incorporating M.2 SSD slots

directly into products, as are

client device makers seeking the

benefits of space efficiency. This

drives volume adoption, reducing

costs for all M.2 users.

The latest storage specification,

SATA Express, redefines a

combination of SATA and PCIe

interfacing, allowing legacy devices

to move forward and new devices

to capture PCIe throughput.

SATA Express also incorporates

both legacy protocols and a new,

faster driver scheme for advanced

operating systems.

SHIFTING FROM SATA TO PCIE

Specification SATA SAS PCIe

Revision 1.0 2.0 3.0 1.0 2.0 3.0 Gen 1 Gen 2 Gen 3

Bandwidth (Gb/sec) 1.5 3.0 6.0 3.0 6.0 12.0 2.0 4.0 7.877

Bandwidth per direction with PCIe multi-lane links (Gb/sec)

2

x2 4.0 8.0 15.75

x4 8.0 16.0 31.5

1 2 3 4 5 6

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