difference between ATA & NON-ATA hard disk [Archive]

DANQU

09-05-2000, 11:45 AM

all this information is Quoted from:
http://webopedia.internet.com/
http://webopedia.internet.com/TERM/A/ATA.html

ATA "Short for AT Attachment, a disk drive implementation that integrates the
controller on the disk drive itself. There are several versions of ATA, all
developed by the Small Form Factor (SFF) Committee:

ATA: Known also as IDE, supports one or two hard drives, a 16-bit
interface and PIO modes 0, 1 and 2.

ATA-2: Supports faster PIO modes (3 and 4) and multiword DMA
modes (1 and 2). Also supports logical block addressing (LBA) and
block transfers. ATA-2 is marketed as Fast ATA and Enhanced IDE(EIDE).

ATA-3: Minor revision to ATA-2.
Ultra-ATA: Also called Ultra-DMA, ATA-33, and DMA-33, supports multiword DMA mode 3 running at 33 MBps.

ATA/66: A new version of ATA proposed by Quantum Corporation,
and supported by Intel, that will double ATA's throughput to 66 MBps.
The first ATA/66 computers are expected to be available in the first half of 1999."

This is non-ATA
And this information is from:

http://webopedia.internet.com/TERM/S/SCSI.html

SCSI

"Abbreviation of Small Computer System Interface. Pronounced "scuzzy,"
SCSI is a parallel interface standard used by Apple Macintosh computers,
PCs, and many UNIX systems for attaching peripheral devices to computers.
Nearly all Apple Macintosh computers, excluding only the earliest Macs and
the recent iMac, come with a SCSI port for attaching devices such as disk
drives and printers.

SCSI interfaces provide for faster data transmission rates (up to megabytesper second) than standard serial and parallel ports. In addition, you can attach many devices to a single SCSI port, so that SCSI is really an I/O bus rather than simply an interface.

Although SCSI is an ANSI standard, there are many variations of it, so two
SCSI interfaces may be incompatible. For example, SCSI supports several
types of connectors.

While SCSI has been the standard interface for Macintoshes, the iMac comes
with IDE, a less expensive interface, in which the controller is integrated into the disk or CD-ROM drive. Other interfaces supported by PCs include enhanced IDE and ESDI for mass storage devices, and Centronics for printers. You can,however, attach SCSI devices to a PC by inserting a SCSI board in one of the expansion slots. Many high-end new PCs come with SCSI built in. Note,however, that the lack of a single SCSI standard means that some devices may not work with some SCSI boards.

The following varieties of SCSI are currently implemented:

SCSI-1: Uses an 8-bit bus, and supports data rates of 4 MBps
SCSI-2: Same as SCSI-1, but uses a 50-pin connector instead of a 25-pin connector, and supports multiple devices. This is what most people mean when they refer to plain SCSI.
Wide SCSI: Uses a wider cable (168 cable lines to 68 pins) to support 16-bit transfers.
Fast SCSI: Uses an 8-bit bus, but doubles the clock rate to support data rates of 10 MBps.
Fast Wide SCSI: Uses a 16-bit bus and supports data rates of 20 MBps.
Ultra SCSI: Uses an 8-bit bus, and supports data rates of 20 MBps.
SCSI-3: Uses a 16-bit bus and supports data rates of 40 MBps. Also called Ultra Wide SCSI.
Ultra2 SCSI: Uses an 8-bit bus and supports data rates of 40 MBps.

Wide Ultra2 SCSI: Uses a 16-bit bus and supports data rates of 80 MBps."

[This message has been edited by DANQU (edited 09-05-2000).]

[This message has been edited by DANQU (edited 09-05-2000).]

dale

09-05-2000, 12:17 PM

From a practical point of view, ATA (or EIDE) and non-ATA (usually SCSI) offer very little difference other than SCSI drives tend to be noticably more expensive then IDE drives. It used to be that IDE was really slow compared to most SCSI drives. Now the performance difference is very little in regards to a PC with the newer Ultra DMA IDE.

The most practical difference I can think of is that IDE is limited to 2 disk drives on the same IDE controller. Where SCSI can have 7. Also SCSI drives tend to have alot more storage (for a lot more money :-).

Also, for SCSI, you can find some hardware level RAID (data redundancy) implementations that make it virtually impossible to ever lose data and also dramatically increases performance. Again, on a PC, there is a certain point where the PC maxes out regardless of how fast the disk drive system might be.

My personal perference is to stick with IDE since they are cheap, usually reliable and "fast enough".

dale