Date: Wed, 1 Nov 2000 00:50:36 -0400 (AST) From: The Hermit Hacker <scrappy@hub.org> To: Tom Samplonius <tom@sdf.com> Cc: freebsd-scsi@freebsd.org Subject: Re: iostat: tps for SCSI drives ... Message-ID: <Pine.BSF.4.21.0011010049310.494-100000@thelab.hub.org> In-Reply-To: <Pine.BSF.4.05.10010312006570.24950-100000@misery.sdf.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 31 Oct 2000, Tom Samplonius wrote:
>
> On Tue, 31 Oct 2000, The Hermit Hacker wrote:
>
> > Okay, how do I read this:
> >
> > pgsql# camcontrol tags da0 -v
> > (pass0:ahc0:0:0:0): dev_openings 41
> > (pass0:ahc0:0:0:0): dev_active 0
> > (pass0:ahc0:0:0:0): devq_openings 41
> > (pass0:ahc0:0:0:0): devq_queued 0
> > (pass0:ahc0:0:0:0): held 0
> > (pass0:ahc0:0:0:0): mintags 2
> > (pass0:ahc0:0:0:0): maxtags 255
>
> I wonder why dev_openings is lower than maxtags?
anything I can look at/check to find out?
> > pgsql# camcontrol tags da1 -v
> > (pass1:ahc0:0:1:0): dev_openings 1
> > (pass1:ahc0:0:1:0): dev_active 0
> > (pass1:ahc0:0:1:0): devq_openings 1
> > (pass1:ahc0:0:1:0): devq_queued 0
> > (pass1:ahc0:0:1:0): held 0
> > (pass1:ahc0:0:1:0): mintags 2
> > (pass1:ahc0:0:1:0): maxtags 255
>
> Here dev_openings is 1, so that would mean that the kernel can't have
> more than one pending command. Since it is a (crappy) Fijitsu drive, I
> would expect that either the drive told that the kernel it won't queue
> commands, or there is quirk entry that disables tags for this drive.
>
> > pgsql# iostat -n5 -t da 5
> > tty da0 da1 da2 cpu
> > tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
> > 77083887 48.00 36 1.67 0.00 0 0.00 0.00 0 0.00 23 0 9 0 68
> > 0 9856 42.97 34 1.45 0.00 0 0.00 8.07 23 0.18 0 0 0 0 0
> > 0 9856 39.77 41 1.57 0.00 0 0.00 8.00 23 0.18 0 0 0 0 0
> >
> > max/mintags aren't a problem ... I take it, from what I'm reading in the
> > man page, the 'pending' is the dev_active field? So, there is nothing
> > pending?
> >
> > The two drives in use above are:
> >
> > da0 at ahc0 bus 0 target 0 lun 0
> > da0: <SEAGATE ST39103LW 0002> Fixed Direct Access SCSI-2 device
> > da0: 80.000MB/s transfers (40.000MHz, offset 15, 16bit), Tagged Queueing Enabled
> > da0: 8683MB (17783240 512 byte sectors: 255H 63S/T 1106C)
> > da2 at ahc0 bus 0 target 2 lun 0
> > da2: <FUJITSU MAE3182LP 0112> Fixed Direct Access SCSI-2 device
> > da2: 80.000MB/s transfers (40.000MHz, offset 63, 16bit), Tagged Queueing Enabled
> > da2: 17431MB (35700480 512 byte sectors: 255H 63S/T 2222C)
> >
> > So, for the Seagate, according to Seagate, the avg seek time is 5.2ms ...
> > so I should max out around 192.3 tps on that drive? I know, not set in
> > stone, but a reasonable number to work with, right? And, from what I can
> > tell about the Fujitso, they are running around 7ms, so ~142tps?
> >
> > Does this make sense?
> >
> >
> >
> >
> >
>
>
Marc G. Fournier ICQ#7615664 IRC Nick: Scrappy
Systems Administrator @ hub.org
primary: scrappy@hub.org secondary: scrappy@{freebsd|postgresql}.org
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-scsi" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.21.0011010049310.494-100000>