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Date:      Wed, 6 Dec 1995 16:38:23 -0600
From:      "Charles F. Randall" <crandall@dmacc.cc.ia.us>
To:        julian@TFS.COM (Julian Elischer)
Cc:        questions@freebsd.org
Subject:   Re: Adaptec 2940W vs Seagate 32550W
Message-ID:  <9512061638.ZM20932@vislab19.dmacc.cc.ia.us>
In-Reply-To: julian@TFS.COM (Julian Elischer) "Re: Adaptec 2940W vs Seagate 32550W" (Dec  4,  5:10pm)
References:  <m0tMltp-0003w9C@TFS.COM>

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Julian,

Note: I've carbon-copied this to questions@freebsd.org

System: Gateway 133MHz Pentium
        64 MB RAM
	Adaptec 2940W SCSI Controller
	Seagate "Barracuda" 2.1 GB Drive (ST32550W)

I've re-partitioned and installed 2.1 on another Barracuda and am seeing
similar (poor) filesystem performance (~3 MB/s compared to the ~5 MB/s
sequential block read rate I saw on the Seagate Hawk drive).

Figuring that I'd messed something up before, I used a "standard" 2047/64/32
geometry and took the default partition sizes. That didn't change performance
much (if any).

Is there some "optimal" geometry and partition size combination that I could
derive from some set of formulas or is this a "black art"? I've appended
Seagate's tech sheet for the 'Cuda drive below.

I can only note that this drive is listed with a speed of 3600 RPM in the
disklabel but it is actually a 7200 RPM drive.

Here are the performance numbers I'm seeing with this configuration.

For the raw device,

flash:~> time dd if=/dev/rsd0 bs=64k of=/dev/null count=1000
1000+0 records in
1000+0 records out
65536000 bytes transferred in 9 secs (7281777 bytes/sec)
0.000u 0.155s 0:09.68 1.5% 63+331k 0+0io 0pf+0w
flash:~> time dd if=/dev/rsd0 bs=64k of=/dev/null count=1000
1000+0 records in
1000+0 records out
65536000 bytes transferred in 9 secs (7281777 bytes/sec)
0.010u 0.148s 0:09.50 1.5% 67+301k 0+0io 0pf+0w


Using Bonnie on /usr/cuda,

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
cuda      128  3217 62.9  3072 13.8  2016 17.3  5067 97.2  5542 23.5 146.3  6.5

The disklabel is, (output of "disklabel -r sd0")

# /dev/rsd0c:
type: SCSI
disk: sd0s1
label:
flags:
bytes/sector: 512
sectors/track: 32
tracks/cylinder: 64
sectors/cylinder: 2048
cylinders: 2047
sectors/unit: 4194058
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:    65536        0    4.2BSD        0     0     0   # (Cyl.    0 - 31)
  b:   284864    65536      swap                        # (Cyl.   32 - 171*)
  c:  4194058        0    unused        0     0         # (Cyl.    0 - 2047*)
  e:    61440   350400    4.2BSD        0     0     0   # (Cyl.  171*- 201)
  f:  3782218   411840    4.2BSD        0     0     0   # (Cyl.  201*- 2047*)

During boot, I noticed the following:

...
ahc0 <Adaptec 2940 SCSI host adapter> rev 0 int a irq 9 on pci0:13
                                                  ^^^^^^
ahc0: 2940 Wide Channel, SCSI Id=7, aic7870, 16 SCBs
ahc0 waiting for scsi devices to settle
(ahc0:0:0): "SEAGATE ST32550W 0016" type 0 fixed SCSI 2
sd0(ahc0:0:0): Direct-Access 2047MB (4194058 512 byte sectors)
de0 <Digital DC21041 Ethernet> rev 17 int a irq 9 on pci0:14
                                            ^^^^^^
de0: DC21041 [10Mb/s] pass 1.1 Ethernet address 00:00:c0:01:7f:c7
...

Is it normal that the controller and ethernet card would both use IRQ 9? Could
this interfere with performance?

If I'm bothering you or there's someone else I should be contacting about this,
just let me know.

Thanks for your help,
-Randy

http://www.seagate.com/techsuppt/drivespecs/scsi/st32550w.html

--- snip ---
                            ST-32550W
                            Barracuda 2LP

       UNFORMATTED CAPACITY (MB) ________________2541.3
       FORMATTED CAPACITY (xx SECTORS) (MB) _____2147.4
       AVERAGE SECTORS PER TRACK ________________108 rounded down
       ACTUATOR TYPE ____________________________ROTARY VOICE COIL
       TRACKS ___________________________________38,610
       CYLINDERS ________________________________3,510 user
       HEADS ______PHYSICAL______________________11
       DISCS (3.5 in) ___________________________6
       MEDIA TYPE _______________________________THIN FILM
       RECORDING METHOD _________________________ZBR RLL (1,7)
       INTERNAL TRANSFER RATE (mbits/sec)________49.4 to 72.0
       EXTERNAL TRANSFER RATE (mbyte/sec) _______5 Async
       EXTERNAL TRANSFER RATE (mbyte/sec) _______5.0 to 20 Sync
       SPINDLE SPEED (RPM) ______________________7,200
       AVERAGE LATENCY (mSEC) ___________________4.17
       BUFFER ___________________________________512 KByte
         Read Look-Ahead, Adaptive,
         Multi-Segmented Cache
       INTERFACE ________________________________SCSI-2 FAST Wide
       BYTES PER TRACK __________________________64,160 average
       SECTORS PER DRIVE ________________________
       TPI (TRACKS PER INCH) ____________________4,048
       BPI (BITS PER INCH) ______________________72,680
       AVERAGE ACCESS (ms) (read/write)__________8.0/9.0
         Drive level without controller overhead
       SINGLE TRACK SEEK (ms) ___________________0.6/0.9
       MAX FULL SEEK (ms) _______________________17/19
       MTBF (power-on hours) ____________________800,000
       SHOCK (G's):
                operating (Read/Write) __________2
                nonoperating ____________________50
       ACOUSTICS (typ/max dBA) __________________4.7/
       POWER REQUIREMENTS: +12V START-UP (amps) _1.26
                           +12V TYPICAL (amps) __0.88 idle
                           +5V START-UP (amps) __0.91
                           +5V TYPICAL (amps) ___0.33 idle
                           IDLE (watts) _________
       LANDING ZONE (cyl) _______________________AUTO PARK
       IBM AT DRIVE TYPE ________________________0 or NONE

       Physical:
                        Height (inches/mm):     1.00/25.4
                        Width  (inches/mm):     4.00/101.6
                        Depth  (inches/mm):     5.75/146.05
                        Weight     (lbs/g):     1.2/545

Already low-level formatted at the factory with 9 spare sectors
per cylinder and 1 spare cylinder per unit.

ZBR = Zone Bit Recording = Variable sectors per track

--- snip ---


-- 
Charles F. Randall              E-mail: crandall@dmacc.cc.ia.us
UNIX Systems Programmer         Voice:  (515) 965-7057  FAX: (515) 965-7305



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