Re: install sloooow doooown

On Tue, 4 Mar 2003 19:09:46 -0500, Ernie Schroder wrote
> On Tuesday 04 March 2003 15:12, [email protected] wrote:
> >You should never install IDE drives on the same
> > channel.
> 
> Would someone tell me why this is right? I've always worked under 
> the assumption that 2 devices on the same IDE channel would both 
> operate at the speed of the slower drive, thus if I had an UDMA 100 
> hard drive and a CD-ROM on the same channel, they would both run at 
> UDMA 33, whereas if I had 2 UDMA hard drives on the same channel,
>  they would operate at their full speed, assuming my controller 
> could handle that. I have always read that mixing hdd's and cd-roms 
> on the same channel was poor practice. 	Who's right? I do see 
> something to be said for Stew's way of thinking, though it's not 
> that often that your 2 hdd's write to each other and even when that 
> happens, it seems to me that data can move between 2 UDMA100 drives 
> faster than between a UDMA 33 drive and a UDMA 100.

Well, in my limited knowledge let me pass on what I have learned.  I come 
from the ole SCSI UNIX days where we would NEVER put an IDE drive into a UNIX 
system.  They all had to be SCSI no matter how much it costed.  The reason at 
the time (might not still be valid but I think it is) was that when the 
system made a disk request to a SCSI device it could disconnect from the 
device and let the device handle the request and when the request was done it 
would then interrupt the cpu to tell it that the request was done.  IN THE 
MEAN TIME, being a UNIX, multitasking machine, the cpu was able to handle a 
multitude of actions in the milli seconds the SCSI controller handled the 
request.  WHERE-AS with IDE, the cpu is NOT able to disconnect from the 
controller after the request is put out to the controller until an answer is 
provided from the controller.  That is my understanding.  Read on for info on 
2 IDE drives on the same controller.

So you might say, so what, we are talking about milli seconds here, well, yes 
we are but we are also talking not about a system sitting in front of a 
single individual waiting for him to finish his next sip of coffee but a 
machine that might be a web server, mail server, authentication server, dhcp 
server, and a hundred other types of servers.  Milli seconds count big time 
here.

Anyway, why not 2 drives on a single IDE chain.  Well, all the info I have 
read about RAID (and ALL of my servers implement some level of RAID) say DO 
NOT put 2 drives on a single IDE chain.  Therefor I don't.

One additional note, ALL of my servers use SCSI drives in a RAID 
configuration for their main system drives.  I use IDE drives in a RAID 
configuration for the users data storage drives and as backup for remote 
systems.  Why??  Well, IDE drives are BIG (GB) & DIRT CHEAP!!!! and I don't 
need big drives for the system, just for the users data.

Hey, I might be wrong in my explanation.  Please chime in if you have more 
technical info to add.

Thanks.

stew
 



> 
> -- 
> Regards, Ernie
> 100% Microsoft and Intel free
> 
> _______________________________________________
> enigma-list mailing list
> [email protected]
> https://listman.redhat.com/mailman/listinfo/enigma-list



>>
>> Stewart M. Ives
>> SofTEC USA
>> 1717 Bridge St
>> New Cumberland, PA 17070
>>
>> Tel: 717-774-4233
>> Fax: 717-774-1808
>> EMail: [email protected]
>> WebSite: www.softecusa.com
>>