ความคิดเห็นที่ 8
 
SATA ผมว่าน่าจะเทียบกับ SAS มากกว่านะ
IDE ค่อยเทียบกับ SCSI
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SAS (Serial Attached SCSI) vs parallel SCSI
* The SAS bus is point-to-point while the SCSI bus is multidrop. Each SAS device is connected by a dedicated link to the initiator, unless an expander is used. If one initiator is connected to one target, there is no opportunity for contention; with parallel SCSI, even this situation could cause contention.
* SAS has no termination issues and does not require terminator packs like parallel SCSI.
* SAS eliminates clock skew.
* SAS supports up to 16,384 devices through the use of expanders while Parallel SCSI is limited to 8 or 16 devices on a single channel.
* SAS supports a higher transfer speed (1.5 OR 3.0 Gbit/s) than most parallel SCSI standards. The speed is realized on each initiator-target connection, hence higher throughput whereas in parallel SCSI the speed is shared across the entire multidrop bus.
* SAS controllers are required by the standard to support SATA devices.
* Both SAS and parallel SCSI use the SCSI command-set.
SAS vs SATA
* SATA devices are uniquely identified by their port number connected to the Host bus adapter while SAS devices are uniquely identified by their World Wide Name (WWN).
* Most SAS drives provide Tagged Command Queuing, while most newer SATA drives provide Native Command Queuing, each of which has its pros and cons.
* SATA follows the ATA command set and thus only supports hard drives and CD/DVD drives. In theory, SAS also supports numerous other devices including scanners and printers. However, this advantage could also be moot, as most such devices have also found alternative paths via such buses as USB, IEEE 1394 (FireWire), and Ethernet.
* SAS hardware allows multipath I/O to devices while SATA (prior to SATA II) does not. Per specification, SATA II makes use of port multipliers to achieve port expansion. Some port multiplier manufacturers have implemented multipath I/O leveraging port multiplier hardware.
* SATA is marketed as a general-purpose successor to Parallel ATA and is now common in the consumer market, while the more expensive SAS is marketed for critical server applications.
* SAS error recovery and reporting utilize SCSI commands which have more functionality than the ATA SMART commands used by SATA drives.
* SAS uses higher signaling voltages (800-1600 mV TX, 275-1600 mV RX) than SATA (400-600 mV TX, 325-600 mV RX). When SAS is mixed with SATA, the SAS drives run at SATA-voltages. One reason for this higher voltage is so SAS may be used in server backplanes.
* Because of its higher signaling voltages, SAS can use cables up to 8 m (25 ft) long, SATA is limited to 1 m (3 ft).
http://en.wikipedia.org/wiki/Serial_Attached_SCSI
จากคุณ :
noraneko 
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11 พ.ย. 51 23:52:41
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