From: mhiroshi@tansei.cc.u-tokyo.ac.jp (H. Murakami)
Newsgroups: comp.unix.bsd
Subject: [386bsd] Queries for the new scsi driver.
Date: 3 Jan 93 09:48:59 GMT
Organization: Hokkaido Univ. However I am subject to tansei for JUNET.

To: comp.unix.bsd
Subject: [386bsd] Queries for the new scsi driver.

I tried the Julian new scsi driver.

However, before I use the aha1542 specific new-scsi driver,
I was able to use two partition on one disk drive for the swap like:

	config   "386bsd"    root on as0 swap on as0b and as0e

And both as0b and as0e were working fine even they are on the identical drive.

After I put the new scsi driver,
in the configuration file for the kernel, 
I removed many unused drivers to save the kernel size 
by commenting out like:

	#options 	NFS
	#disk 	wd1 	at wd0 drive 1
	#device we0 at isa ....
	#device ne0 at isa ..
	#device ec0 at isa ..
	#device is0 at isa ..
	#pseudo-device ddb

for the swap partition I made the line like:

	config   "386bsd"    root on sd0 swap on sd0b and sd0e

My current problem with this julian new scsi driver system is,

the kernel built does not add the partition sd0e for the swap area. 
The "swapon /dev/sd0e" makes error message saying that 
	
	adding swap: failed! (unchanged)
	swapon: /dev/sd0e Device not configured

Note, I have the line in the file /etc/fstab like:

	/dev/sd0e - swap sw - -

This kind of trouble never happened when I used the old scsi driver.
What is the reason that I cannot assign /dev/sd0e  for swap ?

You might think that I should not use two swap reagion on one drive,
however I have a good reason for that.
Sometimes, I just use /dev/sd0b of size 50MB for the swap, and
/dev/sd0e of size 1.0GB for the file system by using newfs
to work with many files.
And sometimes I would like to use both /dev/sd0b and /dev/sd0e to
enable the large virtual memory as large as a giga bytes.
(However I find many trouble to extend the virtual memory of that
size or a few hundred meg, I still making struggle for that.)

BTW.
	What is the advantage of the new scsi driver 
	compared the old scsi drivers ?
	Was the old scsi driver not using DMA transfer
	but program data transfer?
	It seems the data transfer rate measured by the dd command
		/usr/bin/time dd if=/dev/rsd0h of=/dev/null ibs=512x88
	did not speed up compared with that of old scsi driver.
	(comparision is made with only one swap partition system.
	rsd0h is about 300MB large to reduce the effect of the caching.)
	The jumper of the adaptec 1542b card is to use the syncronos
	negotiation mode.
	CPU is 486DX 33MHz, AMI bios 256K cache 16MB Dram, 
	IDA card + adaptec 1542B.
	The scsi disk is Fujitsu's 1.6GB, 11mS, 10MB/Sec peak, SCSI-2 disk.
	It has 512bytes/sector, 88 sectors/track, and 90 rotation/sec means,
	it the data transfer is made ideally, its sustained transfer rate
	is about 4MB/sec, but dd give the number around 1MB/sec.
	(Is 1:1 interleave degrades the performance of the disk?
	 When I purchased the disk, the disk was formatted for MAC,
	 and I do not know what is the current interleave factor of
	 the disk now. )

PS.
	What is the meaning of the message given at the boot time by the
	new scsi driver;

		aha0 reading board settings, 150 nSEC ok, use 200 nSEC
	** aha0 probing for scsi devices **
	dev0,lu0: type 0(direct),fixed 'FUJITSU M2652S-512     008P' scsi2
	sd0: 1651MB, cyls 1944, heads 20, secs 87, bytes/sec 512

	Why it drops from 150 nS to 200nS (and what is the meaning of 150nS)?
	Does this relate to the disk trasfer rate?

		Hiroshi Murakami
		mhiroshi@tansei.cc.u-tokyo.ac.jp
		hiroshi@teine.chem2.hokudai.ac.jp

PS2.
	What is the virtue of ddb ?
Sorry for the buggy English.
Xref: sparky comp.unix.bsd:10492 comp.os.linux:21233