Maxtor disks & DEC5000

[Paulo Jorge Delgado]

	We have installed the following configuration:

DECstation 5000/200 (RISC)	- ULTRIX 4.0	- Maxtor XT-8380S

DECstation 2100 (RISC)		- ULTRIX 4.0	- Maxtor LXT-200

	The disks are rated at 14.5ms and 15ms typical seek time against 24ms
for DEC's RZ55 disks, but I am getting very bad performance ratios for the
Maxtor disks, using the DISKPERF benchmarks:

-----------------------------------------------------------------------------
DEC 5000 with RZ55

File create/delete:     create 19 files/sec, delete 60 files/sec
Directory scan:         4083 entries/sec
Seek/read test:         999 seek/reads per second
r/w speed:              buf 512 bytes, rd 983040 byte/sec, wr 434492 byte/sec
r/w speed:              buf 4096 bytes, rd 964947 byte/sec, wr 340815 byte/sec
r/w speed:              buf 8192 bytes, rd 995483 byte/sec, wr 342299 byte/sec
r/w speed:              buf 32768 bytes, rd 967916 byte/sec, wr 341926 byte/sec

-----------------------------------------------------------------------------
DEC 5000 with Maxtor XT-8380S (installed as a RZ55)

File create/delete:     create 4 files/sec, delete 59 files/sec
Directory scan:         4764 entries/sec
Seek/read test:         503 seek/reads per second
r/w speed:              buf 512 bytes, rd 307801 byte/sec, wr 350303 byte/sec
r/w speed:              buf 4096 bytes, rd 327680 byte/sec, wr 281119 byte/sec
r/w speed:              buf 8192 bytes, rd 328364 byte/sec, wr 291541 byte/sec
r/w speed:              buf 32768 bytes, rd 299023 byte/sec, wr 291811 byte/sec


-----------------------------------------------------------------------------
DEC 2100 with Maxtor LXT-200 (installed as a RZ55)

File create/delete:     create 18 files/sec, delete 59 files/sec
Directory scan:         1282 entries/sec
Seek/read test:         416 seek/reads per second
r/w speed:              buf 512 bytes, rd 298173 byte/sec, wr 343420 byte/sec
r/w speed:              buf 4096 bytes, rd 313007 byte/sec, wr 419990 byte/sec
r/w speed:              buf 8192 bytes, rd 313319 byte/sec, wr 418871 byte/sec
r/w speed:              buf 32768 bytes, rd 301026 byte/sec, wr 441196 byte/sec

	I believe this bad performance of the Maxtor disks is due to the kernel
not being able to use all the features of this disks. There is no entry in the
Ultrix tables (/sys/data/scsi_data.c , /etc/disktab) for the Maxtor disks, so I
had to install them as RZ55 devices.
	I would like to know if there is any configuration procedure I could do
(eg : recompiling the kernel with some changes), to improve the disks
performance (I am mainly interested in improving the DEC 5000-Maxtor XT8380S
pair performance).
	Many thanks.


Paulo Jorge Delgado		email:  pjd at inesc.inesc.pt
INESC - Lisboa - Portugal		...!mcsun!inesc!pjd
INESC - Lisboa - Portugal		PSI%(+0268)004010314::PJD