Date: Mon, 20 Oct 1997 20:24:34 -0500 From: dkelly@hiwaay.net To: Joe McGuckin <joe@via.net> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: 2.2.2-RELEASE '875 SCSI won't negotiage Message-ID: <199710210124.UAA14405@nospam.hiwaay.net> In-Reply-To: Message from Joe McGuckin <joe@via.net> of "Mon, 20 Oct 1997 15:06:28 PDT." <199710202206.PAA17351@monk.via.net>
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Joe McGuckin writes:
>
> (ncr0:0:0): "QUANTUM XP32275W LXY4" type 0 fixed SCSI 2
> sd0(ncr0:0:0): Direct-Access
> sd0(ncr0:0:0): WIDE SCSI (16 bit) enabled
> sd0(ncr0:0:0): 20.0 MB/s (100 ns, offset 16)
>
>
> Shouldn't this report back 40.0 MB/s for fast wide ultra ?
Probably should. But it might not really be up to 40 MB/sec. The MB/sec and
ns numbers agree. I got this the other day on my new Asus SC875 and 9G IBM
UW drive:
ncr0 <ncr 53c875 fast20 wide scsi> rev 3 int a irq 11 on pci0:11
ncr0 waiting for scsi devices to settle
(ncr0:0:0): WIDE SCSI (16 bit) enabled(ncr0:0:0): 10.0 MB/s (200 ns, offset 15)
(ncr0:0:0): "IBM OEM DCHS09W 2222" type 0 fixed SCSI 2
sd1(ncr0:0:0): Direct-Access
sd1(ncr0:0:0): WIDE SCSI (16 bit) enabled
sd1(ncr0:0:0): 20.0 MB/s (100 ns, offset 15)
8689MB (17796077 512 byte sectors)
Am mildly concerned about the 10.0 MB/s message that starts it off. And I'm
thinking about the whole issue because I'm not certian my performance is up
to snuff. Using bonnie:
IBM OEM DCHS09W on Asus SC875, new & empty 2.4G filesystem at end of disk:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
100 3972 41.8 3986 14.6 2234 7.5 6700 76.3 8228 16.4 108.4 2.6
^^^^ this seems low
SEAGATE ST32550N on Adaptec 2940 (AIC-7870) old 86% full 1.8G fs
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
100 3980 43.2 4402 13.9 1774 5.0 4260 48.3 3759 5.7 71.5 1.5
System is an Asus P6NP5 PPro-166/512k 32M RAM.
# scsi -f /dev/rsd1c -m 8 -P 3
WCE: 0
MF: 0
RCD: 0
Demand Retention Priority: 1
Write Retention Priority: 1
Disable Pre-fetch Transfer Length: 65535
Minimum Pre-fetch: 0
Maximum Pre-fetch: 65535
Maximum Pre-fetch Ceiling: 65535
Observed the Seagate had the WCE set (Write Cache Enable) so I did the same
for the IBM.
Flipped the WCE bit from 0 to 1 and got this on the IBM (last fs):
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
100 7402 76.5 7927 31.0 2311 7.8 6587 75.2 8207 16.2 110.3 2.5
^^^^ ^^^^ both of these are *much* better.
After enabling the write cache, this drive is comparable to the new Seagate
4.3G Barracuda on an Adaptec 2940AU (AIC-7860) and P-133 I'm playing with
at work:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
100 3653 75.6 8523 36.4 2293 15.9 3595 70.6 9183 38.4 92.2 4.3
It really bugged me that my UW HD on PentiumPro was being beat by a P-133
with narrow SCSI. Then I began to wonder if there was a difference between
inner and outer tracks. This fs starts about 200M past block 0, while the
above (up 2, the IBM) starts 2.4G from the end of the disk:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
100 8098 79.7 9385 38.3 2758 9.2 6426 74.0 9772 20.1 111.2 2.5
...and that's more like it!
What really brought all this about was when a dump | restore from old 2.1G
Seagate to new 9.1G IBM reported 500k/sec thruput. The IBM fs's were still
mounted async as sysinstall left them.
--
David Kelly N4HHE, dkelly@hiwaay.net
=====================================================================
The human mind ordinarily operates at only ten percent of its
capacity -- the rest is overhead for the operating system.
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