On Sun, 2 Feb 2003, Greg 'groggy' Lehey wrote:

[GgL:   #  dd if=/dev/ad0s1c of=/dev/null bs=128k &
[GgL:   # iostat ad0 1
[GgL:         tty             ad0             cpu
[GgL:    tin tout  KB/t tps  MB/s  us ni sy in id
[GgL:    164  158  0.00   0  0.00   9  0  4  3 85
[GgL:      1  340 128.00 190 23.71   3  0  8 12 78
[GgL:      0   44 128.00 188 23.52   1  0  7  5 88
[GgL:      0  155 128.00 187 23.37   2  0  5  5 88
[GgL:      0  155 128.00 191 23.91   2  0  6  5 88
[GgL:      0  154 128.00 191 23.89   6  0  6  5 82
[GgL:      0  155 128.00 191 23.89   6  0  6  3 84
[GgL:   ^C
[GgL:   # uname -a
[GgL:   FreeBSD echunga.lemis.com 4.7-STABLE FreeBSD 4.7-STABLE #0: Wed Dec 18 14:20:56 CST 2002     grog@echunga.lemis.com:/src/FreeBSD/4-STABLE-ECHUNGA/src/sys/compile/ECHUNGA  i386
[GgL:   # dmesg | grep ad0
[GgL:   ad0: 13042MB <WDC WD136BA> [26500/16/63] at ata0-master UDMA66

Wow, that's definitely disk-dependent unless our driver (or FreeBSD's) is
lying:

rivendell 585# dmesg | grep wd2
wd2 at pciide0 channel 1 drive 1: <IC35L060AVVA07-0>
wd2: drive supports 16-sector PIO transfers, LBA addressing
wd2: 58644 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 120103200 sectors
wd2: 32-bit data port
wd2: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 5 (Ultra/100)
wd2(pciide0:1:1): using PIO mode 4, Ultra-DMA mode 5 (Ultra/100) (using \
	 DMA data transfers)
rivendell 586# dd if=/dev/wd2p of=/dev/null bs=128k & iostat wd2 1
[3] 27956
      tty            wd2             cpu
 tin tout  KB/t t/s MB/s  us ni sy in id
   0   14 31.02   0 0.01   2  0  0  0 98
   0  250 32.00 119 3.71   0  0  5  1 94
   0   83 32.00 116 3.62   0  0  4  1 95
   0   83 32.00 122 3.81   0  0  2  0 98
   0   83 32.00 122 3.81   0  0  2  0 98
^?
rivendell 587#


[GgL:
[GgL: I don't know what the real limit is, though.
[GgL:
[GgL: Greg
[GgL: --
[GgL: Finger grog@lemis.com for PGP public key
[GgL: See complete headers for address and phone numbers
[GgL:


				--*greywolf;
--
NetBSD: Beyond Windows