VLB IDE cards

VLB IDE cards

Post by Christian Pablo Tagtachi » Thu, 02 Dec 1993 09:22:18



Hello, I tried an IDE VESA local bus card. I found almost no difference
in the transfer speed. Is there any difference in respect to the bus
loading if I use a VESA IDE instead of using the traditional ISA IDE?
Thank you
 
 
 

VLB IDE cards

Post by Matthew Rhot » Fri, 03 Dec 1993 04:34:37



Quote:>Hello, I tried an IDE VESA local bus card. I found almost no difference
>in the transfer speed. Is there any difference in respect to the bus
>loading if I use a VESA IDE instead of using the traditional ISA IDE?
>Thank you

I recently moved my IDE disks off my local bus, onto an $8.99 16-bit
IDE controller. Oh, I also moved my floppies with the IDE disks,
woohooooo. (I'm freeing up a local bus slot for an Ultrastor 34F - as
an aside, I can now highly recommend the Boca 2x4 four-serial-port and
two-parallel-port card.)

I get roughly the same performance off the local bus as on with my IDE
disks.  iozone reports performance around 10% slower on ISA vs VLB.
(12-16mb file, 8mb RAM in the machine.) A low-level speed test called
'coretest' actually reported a higher throughput - but since I use the
filesystem every day, iozone is a better metric for me.

There are two WD Caviar 2200's* off the controller, if that
makes any difference. Oh, and there's only one other VLB slot in this
motherboard, which has a Diamond Stealth 24 attached to it.  (Yes,
yes, I know. Bleh.)

I don't know if I should have expected this. I'm not complaining,
naturally - I expected a heinous slowdown - but it did surprise me.
My VLB IDE controller is a fairly anonymous one; I don't know how
good it is.

And, I don't have an answer to the previous poster's question about
loading (on the CPU?) for each bus. But I thought this information
might be of interest.

 -matt
--
Matthew Rhoten - his .signature, his opinions.

"I'm not sure I remember HOW to sleep."
 -Dan Sommerfield

 
 
 

VLB IDE cards

Post by Mast » Fri, 03 Dec 1993 05:15:00



Quote:>Hello, I tried an IDE VESA local bus card. I found almost no difference
>in the transfer speed. Is there any difference in respect to the bus
>loading if I use a VESA IDE instead of using the traditional ISA IDE?
>Thank you

I have been thinking about this, because I wondered it myself...

RAM only runs at less than 14 MHz (with 70 ns RAM) and ISA runs at 8MHz.
Theoretically there must be a maximum possible difference factor of
(14/8)*(32/16)=3.50 between the loads. But it is questionnable whether the RAM
really makes 14 MHz and not just the ISA speed, and if your VLB-card just
allows 16 bit transfers, the difference won't be much. (Local Bus was
invented for making fast I/O transfers to the processor, and not RAM I suppose)

I have never seen test-results on this bus-load issue, but certainly am
interested.

Robert

 
 
 

1. Enhanced VLB IDE cards?

I need to know if there is a dual port Enhanced IDE VLB card driver for
Linux?  Right now I am using a secondard ISA IDE controller to get a 3rd
IDE hard drive.  I went out and bought a VLB dual port IDE controller
(supports 4 IDE drives).  Is there any support for this card, or am I
SOL?

Thanx

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