From: buhr@ccu.umanitoba.ca (Kevin Andrew Buhr)
Subject: Summary:  Advice wanted on using ESDI and IDE drives with OS/2
Organization: University of Manitoba, Winnipeg, Canada
Date: Tue, 8 Sep 1992 19:17:39 GMT


In <BUHR.92Sep2172726@asimov.umanitoba.ca>, I asked:

[ regarding putting ESDI and IDE drives on the same EISA bus . . . ]

> Is there any problem with this setup other than possible performance
> problems with the IDE drives?  Is anyone out there running IDE and
> ESDI technology side-by-side on an OS/2 EISA box or on any box?  Do
> the cards co-exist peacefully and will OS/2 recognize them properly?
> I don't have the particulars on our ESDI drive or controller, but is
> there anything to watch out for here?

In summary, the consensus was that OS/2 does *not* support EISA and
IDE at the same time using the default driver, IBM?S506.ADD, so you
have to use the INT13 generic driver and suffer a severe performance
degradation.

I was advised to sell the ESDI and buy either IDE or SCSI.

Thanks to the following people for their replies:

	"Timothy F. Sipples" <sip1@midway.uchicago.edu>
	"Robert J. McNamara" <rob@cad4.lbl.gov>
	"Roger Lynx" <rlynx@netcom.com>
	"Tom Hatton" <hatton@cgl.ucsf.EDU>

The editted text of their replies follows the signature.

Kevin Buhr <buhr@ccu.UManitoba.CA>

				*	*	*

. Date: Wed, 2 Sep 92 18:55:13 CDT
. From: "Timothy F. Sipples" <sip1@midway.uchicago.edu>
. 
. I know some people get away with it, but it gets dicey mixing drive
. technologies.  My recommendation would be to sell the ESDI adapter and
. hard drive (to acquire some funds for the upgrade), then purchase
. whatever IDE storage you need.

				*	*	*

. Date: Wed, 2 Sep 92 18:59:06 pdt
. From: rob@cad4.lbl.gov (Robert J. McNamara)
. 
. I don't believe that'll work. At least, thats the rule of thumb. I think
. the only case where two controllers will get along well is if one
. of them is a SCSI. (write back and tell me if I'm wrong though! :^) )

				*	*	*

. Date: Thu, 3 Sep 92 07:44:24 PDT
. From: rlynx@netcom.com (Roger Lynx)
.
[ Regarding mixing IDE and ESDI ]
. That might be the case. But....IMHO IDE drives suffer a problem: they
. cannot be low level formatted and it is an *issue* for me. Some folks
. do not care therefore IDE is what they buy.
. 	
[ Regarding best partitioning ]
. I suggest this:
. 	1MB	 boot manager
. 	10MB	pri DOS C:
. 	60MB	log OS/2 HPFS C: system (bootable)
. 	30MD	log OS/2 HPFS D: data	(non-bootable)
. This way OS/2 will 'see' the FAT, HPFS but DOS won't interefer with HPFS.
. (I have to check it, it's been some time I did that, so take a
. truckload of salt on it :-))
. 
[ Regarding performance degradation ]
. My understanding is such: If you use IDE, ESDI and RLL you use
. 'generic' drivers that go thru BIOS to 'talk' to the drive. And this
. turns out to be a slow. BUT.....if you use SCSI (with HA
. manufacturer dedicated driver) then OS/2 flies like bat out of hell
. :-) Why? Because...the OS/2 is multitasking and it can ask the drive
. for different things at the same time, but IDE, ESDI and RLL are
. 'single task' interfaces.
.
[ Regarding what the acronyms stand for ]
. BTW, 	IDE = Integrated Drive Electronics (i.e. controller on drive's board)
. 	ESDI = Enhanced Standard Drive Interface (juiced up ST506)
. 	SCSI = Small Computer System Interface
. 	RLL = Run Length Limited (juiced up ST506, not as good as ESDI)
. 
[ Summary ]
. My advice: forget IDE and RLL.
. 	Most drive manufacturers stopped making big ESDI drives, it is
. dying std. I like it in single user/DOS environment for its speed. (That 
. includes Windoze :-))
. 
. I am very happy with Ultrastor (non EISA). They have quite a selection and
. good support.
. WD1007 is not soo good, just one suffix batch (don't remeber which one)
. SE2 is good!
. 
. Conclusion: GO SCSI! (No ADAPTEC, though)

				*	*	*

. Date: Thu, 3 Sep 92 13:50:25 -0700
. From: hatton@cgl.ucsf.EDU
. 
[ Some stuff omitted ]
.
. In any case, OS/2 will *not* allow mixed interfaces with the standard
. disk driver (ibm1s506.add) so you will only be able to do this, as far
. as I understand it, by using the generic int13 driver instead (I think
. you just rename the int13 driver to ibm1s506.add and let it go). This 
. allows the BIOS of the controllers to do their own thing and should
. allow the system to function; but there is a big speed penalty, according
. to those who have had to use the int13 driver and subsequently managed
. to change to the .add driver.
. 
. I have seen reports from people who have done this to change a system over
. from one format to another without replacing files from tape or floppies -
. they set it up with both under the in13, copied from one disk to the new
. one, and then changed to the .add driver after removing the old disk.
. IDE or ESDI run OK with OS/2 on their own, but you can't mix according to
. all the info I've seen.

[ To which I replied . . . ]

> From: buhr
> To: hatton@cgl.ucsf.EDU
> 
> Okay, thanks for the info.  How about mixing SCSI and ESDI on the same
> bus?  Can OS/2 use both ibm1s506.add and ibm1scsi.add or whatever?

[ To which Tom replied . . . ]

. Date: Thu, 3 Sep 92 14:11:06 -0700
. From: hatton@cgl.ucsf.edu (Tom Hatton)
. To: buhr@ccu.UManitoba.CA
. 
. I think the same caveat applies. I don't believe you can do both at the
. same time. But I haven't tried it, so I can't say for sure. You could try
. setting it up, and trying to boot - worst that can happen is a hang; in
. addition you might try giving the IBM support line a call. This may have 
. been thrashed out before.
Newsgroups: comp.os.os2.misc