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Date:      Wed, 29 Jul 2015 12:30:27 +1000
From:      David Gwynne <david@gwynne.id.au>
To:        Dan Langille <dan@langille.org>
Cc:        freebsd-scsi@freebsd.org
Subject:   Re: dmesg output not as expected
Message-ID:  <B45B20A9-7AC9-413B-A8CB-934BBA2D56A1@gwynne.id.au>
In-Reply-To: <BFD44FE6-CCF0-4973-8893-86D7E58DF7C9@langille.org>
References:  <5A302DC6-C3EF-4DB1-8AD1-A0314C048A28@langille.org> <BFD44FE6-CCF0-4973-8893-86D7E58DF7C9@langille.org>

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> On 29 Jul 2015, at 12:18, Dan Langille <dan@langille.org> wrote:
>=20
>>=20
>> On Jul 28, 2015, at 1:01 PM, Dan Langille <dan@langille.org> wrote:
>>=20
>> I wish to move a tape library from one system to another.  Today I =
moved the cable from one system to another and ran 'camcontrol rescan =
all'.
>>=20
>> For sa0, why do I see 80MB/s on the old system vs 40MB/s on the new =
system?  Is this card related? Slot related?
>>=20
>> Similarly, ch0 goes from 20MB/s to 3.3MB/s....=20
>>=20
>> I was hoping for a speed boost.  :)
>>=20
>> Some of the camcontrol devlist output includes:
>>=20
>> <COMPAQ SuperDLT1 5F5F>            at scbus14 target 1 lun 0 =
(pass11,sa0)
>> <COMPAQ MSL5000 Series 0520>       at scbus14 target 3 lun 0 =
(pass12,ch0)
>>=20
>> This is on the existing system:
>>=20
>> I *think* this system holds a Symbios Ultra2 32-bit PCI SCSI Adapter =
SYM8951U
>>=20
>> Jul 23 13:24:19 knew kernel: sym0: <895> port 0xe000-0xe0ff mem =
0xfebeec00-0xfebeecff,0xfebef000-0xfebeffff irq 22 at device 2.0 on pci4
>> Jul 23 13:24:19 knew kernel: sym0: No NVRAM, ID 7, Fast-40, LVD, =
parity checking
>>=20
>> Jul 23 13:24:19 knew kernel: sa0 at sym0 bus 0 scbus7 target 1 lun 0
>> Jul 23 13:24:19 knew kernel: sa0: <COMPAQ SuperDLT1 5F5F> Removable =
Sequential Access SCSI-2 device=20
>> Jul 23 13:24:19 knew kernel: sa0: Serial Number CXB46H0716 =20
>> Jul 23 13:24:19 knew kernel: sa0: 80.000MB/s transfers (40.000MHz, =
offset 31, 16bit)
>>=20
>> Jul 23 13:24:19 knew kernel: ch0 at sym0 bus 0 scbus7 target 3 lun 0
>> Jul 23 13:24:19 knew kernel: ch0: <COMPAQ MSL5000 Series 0520> =
Removable Changer SCSI-2 device=20
>> Jul 23 13:24:19 knew kernel: ch0: Serial Number 3G22JJP38S46
>> Jul 23 13:24:19 knew kernel: ch0: 20.000MB/s transfers (10.000MHz, =
offset 15, 16bit)
>> Jul 23 13:24:19 knew kernel: ch0: 25 slots, 1 drive, 1 picker, 1 =
portal
>> Jul 23 13:24:19 knew kernel: ch0: quirks=3D0x2<NO_DVCID>
>>=20
>> This is the same tape drive on another system:
>>=20
>> LSI Logic Ultra320 (LSI20320IE) SCSI PCI-E
>>=20
>> mpt0: <LSILogic 1030 Ultra4 Adapter> port 0x8000-0x80ff mem =
0xfb220000-0xfb23ffff,0xfb200000-0xfb21ffff irq 19 at device 8.0 on =
pci15
>> mpt0: MPI Version=3D1.2.14.0
>>=20
>> Jul 28 16:36:31 varm kernel: sa0 at mpt0 bus 0 scbus14 target 1 lun 0
>> Jul 28 16:36:31 varm kernel: sa0: <COMPAQ SuperDLT1 5F5F> Removable =
Sequential Access SCSI-2 device
>> Jul 28 16:36:31 varm kernel: sa0: Serial Number CXB46H0716 =20
>> Jul 28 16:36:31 varm kernel: sa0: 40.000MB/s transfers (40.000MHz DT, =
offset 6)
>>=20
>> Jul 28 16:37:03 varm kernel: ch0 at mpt0 bus 0 scbus14 target 3 lun 0
>> Jul 28 16:37:03 varm kernel: ch0: <COMPAQ MSL5000 Series 0520> =
Removable Changer SCSI-2 device
>> Jul 28 16:37:03 varm kernel: ch0: Serial Number 3G22JJP38S46
>> Jul 28 16:37:03 varm kernel: ch0: 3.300MB/s transfers
>> Jul 28 16:37:03 varm kernel: ch0: 25 slots, 1 drive, 1 picker, 1 =
portal
>> Jul 28 16:37:03 varm kernel: ch0: quirks=3D0x2<NO_DVCID>
>=20
> After rebooting this server, I see this in /var/run/dmesg.  Why does =
it change?
>=20
> ch0 at mpt0 bus 0 scbus14 target 3 lun 0
> ch0: <COMPAQ MSL5000 Series 0520> Removable Changer SCSI-2 device
> ch0: Serial Number 3G22JJP38S46
> ch0: 20.000MB/s transfers (10.000MHz DT, offset 15, 16bit)
> ch0: 25 slots, 1 drive, 1 picker, 1 portal
> ch0: quirks=3D0x2<NO_DVCID>
>=20
> I was hoping to get more through put on this newer system with a =
different card.  =46rom what I see, my speed is only half of what it =
was.
>=20
> I'm using a PCI-E 3.0 X8 (in X16) slot. Have I missing something?

technically parallel scsi isn't a hot pluggable medium. rebooting likely =
lets it settle and negotiate better.

you probably shouldnt care about the speed you talk to the changer at =
btw. you're not sending data to the changer device, just commands to =
move tapes around which are very low bandwidth.

did your tape device negotiate faster after the reboot?

dlg=



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