Question for you SCSI Storage Phreaks!

[Hamburgerpimp]

I know this will get answered much faster in Off Topic:


I'm not running this Harddrive on a U160 controller. It's on a Tekram 390U2W with 80m/s max transfer. This IBM drive has 4.9ms access time.

My question is, does my access time remain the same whether on a U160 or U2W controller?? Or, is U160 a waste of time and money?

 

[SackOfAllTrades]

that question should be on the SATs!

 

[rgwalt]

Yep, access time depends on how fast your drive can find the data on the platters, not on the data transfer rate.

Ryan

 

[Hamburgerpimp]

Thanks, now another question:

So, how is the max U160 achieved if the PCI bus only supports 132M/s??

 

[jimmygates]

I don't know about about PCI U160 cards but I have an Adaptec 29160 U160 card that supports both 32bit and 64bit PCI. In the manual it states the card can't reach the max in 32bit mode...which means normal PCI users are out of luck . I believe 64bit PCI slots only appear in server boards?



-Jimbo

 

[yakko]

Since we are on the subject what about on board SCSI?

 

[Hamburgerpimp]

OB SCSI, usually on dual cpu server mobos and not many applications for the home user take advantage of dual CPUs.

(I'm sure you know that, not trying to be smart, here.)

 

[PCResources]

<< My question is, does my access time remain the same whether on a U160 or U2W controller?? Or, is U160 a waste of time and money? >>



The access time remains the same, the U160 interface only becomes useful when you add more drives as all drives on one SCSI channel will share the maximum bandwidth...

So, to answer your question, for your one drive, the U2W will be as fast as an U160 solution, but if you add a few drives, a U160 card would increase maximum transfer rates...

Patrick

 

[PCResources]

<< OB SCSI, usually on dual cpu server mobos and not many applications for the home user take advantage of dual CPUs. >>



Many non server boards can be found with OB SCSI interface, like the MSI K7Master, the OB SCSI controller is connected to the PCI bridge, so if the motherboard uses 32bit PCI, the OB controller would use a 32bit wide interface.

Patrick

 

[dman]

Shouldn't be a problem with 32bit PCI. You have to transfer data from multiple devices simultaneously for it to reach max speed. If you only have 1-2 SCSI Drives, you won't reach max. If you've got money to spend go with a Hardware RAID solution.

[edit]removed stupid comment about minor increase in speed[/edit]

 

[Demon-Xanth]

Ultra160 in a 33/32 slot can do 160MB/s BETWEEN DEVICES. Not every piece of data must hit the PCI bus. Access time is largely unaffected by the speed of data on the cable, it takes the same amount of time to move the head and have the disk spin to the appropriate sector

 

[dman]

Iff the devices can xfer at 160MB/s. I doubt many can and sustain it for very long = not very useful for desktop user = waste of money.

 

[PCResources]

<< If you've got money to waste for minor increases in speed, go with a Hardware RAID solution. >>



Yeah, minor increases with a HW RAID solution, a SCSI HW RAID solution?

Man, i laughed at this post, that is just soooo funny...

I mean, first of all, choose a good raid level, you will have redundancy, i bet dman6666 doesn't even know what redundany is...

And a &quot;minor&quot; increase in speed, well, that is just laughable...

Patrick

 

[PCResources]

<< Ultra160 in a 33/32 slot can do 160MB/s BETWEEN DEVICES >>



However, most of that data is transferred to the bus interface... There goes your logic...

Patrick

 

[PCResources]

<< Iff the devices can xfer at 160MB/s. I doubt many can and sustain it for very long = not very useful for desktop user = waste of money. >>



If all of the devices on the chain can transfer a burst speed that equates to 160MB/s... the U160 chain is 15 units long... total of sustained transfer by using a 3 drive config... 170MB when using seagate drives...

I think your theory is flawed...

Patrick

 

[Demon-Xanth]

SCSI has never really been ment to be a single drive interface. Ultra160 and 320 are useful because you can pack 15 drives on a single cable. At which point that bandwidth is looking real attractive. And not every SCSI device is a hard drive.

You can do SCSI CDROM>SCSI CD-r with very low CPU usage because not all data has to be piped through the CPU, or even slap on a SCSI scanner.

 

[PCResources]

<< SCSI has never really been ment to be a single drive interface. Ultra160 and 320 are useful because you can pack 15 drives on a single cable. At which point that bandwidth is looking real attractive. And not every SCSI device is a hard drive. >>



Exactly..

Patrick