SCSI compared to IDE

[Guest]

I want to know how much performace difference there is between the fastest IDE and SCSI HD. Obviously IDE is alot cheaper.. I have been looking at the WD or Seagate SCSI HD's 10-15k rpm 8mb cache.. also what is the difference between the 68-80 pin just connection ? and there are also several modles AV-LV-160m ? I'm asuming that the fastest IDE drive is a Ultra ATA-100 7,200rpm HD.. Someone please help me with this 😛
Thanks

 

[RamaV]

80 pin connection is for a server bay or hot swap rack, bascially only difference is the ribbon/pins include power for the drive, 68 pin is essentially the same, only you have to use a different plug/wire for power.

As for the rest of your question, hehehehe, thats a debate been goin on for a long time here. The difference is there, not as big as it used to be, but its there. the IBM 75GXP offer an aweseom IDE drive. It still cant quite catch the access times or sustained transfer rates of some SCSI drives, but then you get a boatload more space for what you pay for.

Personally, im just now buying the new Fujitsu MAJ 10k drives (a pair of them). They have very good transfer times, seek times, but are just about as quiet and cool as an IDE. thats somehting to consider as well, if you go SCSI, expect to hear it, and expect to have to cool it.

Also have you considered a RAID array..? If you go IDE, the saving in cost of the drive may allow you to add this benefit. Depends on your needs

Rama

" He who (BLEEPS) nuns, will later join the church " Joe Strummer, The Clash - "Death or Glory"

 

[Kelledin]

Hmmm...well...

The fastest 10,000 RPM SCSI drive (the Quantum Atlas 10K II, or the Cheetah 36XL) gets maybe a 10% increase in speed over the fastest IDE drive (the IBM 7200RPM 75GXP). The Seagate Cheetah X15 has rather odd performance stats, mainly due to extreme design differences from earlier Seagate Cheetahs (see <A HREF="http://www.storagereview.com/" target="_new">http://www.storagereview.com/</A> for performance details). For desktop use, if you plan to only have one hard drive in your system at any time, IDE does just fine.

If you plan to have more than two hard drives in your system, you might seriously consider SCSI. SCSI does much better than IDE when you have multiple drives on the same bus; this is because the SCSI bus is multi-threaded (meaning that drives don't have to wait on each other), while the IDE bus is single-threaded (meaning that a drive will often have to wait for other devices to finish their work before it can do anything).

There's also the Escalade IDE RAID controller, which is actually an excellent 4-channel IDE RAID controller costing less than just about any SCSI RAID controller on the market.

If you plan to do RAID, SCSI still has advantages, mainly due to expandability and its multi-threaded bus (see above, advantages on SCSI for multiple drives). SCSI also has the ability to sync the spindle speed on multiple drives, a feature that enhances RAID performance a bit. SCSI has a theoretical bandwidth advantage over IDE (160MB/sec vs. 100MB/sec), but this hardly makes any difference until you get into extremely large RAID arrays.

If you really want speed and have a lot of money to burn, another thing you might consider is solid state drives--drives which store data primarily in some form of RAM. Quantum makes solid state disks; other companies make solid-state "disks" in the form of PCI add-in cards with RAM slots. Due to being memory-based, solid-state disks thoroughly wail on most RAID arrays. They are also very, very expensive (I've seen one PCI solid-state "disk" for $5000--and that was just the baseboard with no memory. It was expandable to 8GB PC100 SDRAM capacity).

As for SCA, it's mainly just an 80-pin single connector. versus having the 68-pin bus connector, the ID connector, and the power connector separated. It's primarily designed to be hot-swappable and plug into an SCA backplane. You can still make 68-pin drives hot-swappable though; Kingston, Adjile, Antec, Wetex, and several other companies make hot-swap carriers, devices which fit in 5.25" bays and allow 68-pin drives to be hot-swapped. The problem with these hot-swap carrier solutions is that they tend to push the SCSI "stub length" to its specified limits or even beyond, making the SCSI bus less electrically stable than an SCA backplane solution. Adjile carriers in particular are bad about this; even though they are supposed to be Ultra160 capable, they sometimes have to be set to work at Ultra2 (80MB/sec) just to function properly.

Kelledin
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