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Date:      Fri, 27 Feb 2015 17:56:42 -0500
From:      Dan Langille <dan@langille.org>
To:        "Kenneth D. Merry" <ken@freebsd.org>
Cc:        current@freebsd.org, scsi@freebsd.org
Subject:   Re: sa(4) driver changes available for test
Message-ID:  <5568AE5F-193C-47A8-A24B-FB2C36E37BC9@langille.org>
In-Reply-To: <20150217183645.GA30947@mithlond.kdm.org>
References:  <20150214003232.GA63990@mithlond.kdm.org> <7CA52DF3-E073-4F50-BE4E-01C51CCDF2C7@langille.org> <20150217183645.GA30947@mithlond.kdm.org>

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> On Feb 17, 2015, at 1:36 PM, Kenneth D. Merry <ken@freebsd.org> wrote:
>=20
> On Sat, Feb 14, 2015 at 18:22:43 -0500, Dan Langille wrote:
>>=20
>>> On Feb 13, 2015, at 7:32 PM, Kenneth D. Merry <ken@freebsd.org> =
wrote:
>>>=20
>>>=20
>>> I have a fairly large set of changes to the sa(4) driver and mt(1) =
driver
>>> that I'm planning to commit in the near future.
>>>=20
>>> A description of the changes is here and below in this message.
>>>=20
>>> If you have tape hardware and the inclination, I'd appreciate =
testing and
>>> feedback.
>>=20
>> I have a DLT 8000 and an SDLT 220.
>>=20
>> I don't have anything running current, but I have a spare machine =
which I could use for testing.
>>=20
>> Do you see any value is tests with that hardware? I'd be testing it =
via Bacula.
>>=20
>> disclosure: I'm the sysutils/bacula-* maintainer and a Bacula =
committer.
>>=20
>=20
> Actually, yes.  Bacula is a bit tricky to configure, so your trying it =
out
> would be helpful if you have the time.

I have been unable to test yet.  I've encountered time and hardware =
issues.

I may be able to try tomorrow.


>=20
> In looking at the manuals for both the SDLT 220 and the DLT 8000, they =
both
> claim to support long position information for the SCSI READ POSITION
> command.
>=20
> You can see what I'm talking about by doing:
>=20
> mt eod
> mt status
>=20
> On my DDS-4 tape drive, this shows:
>=20
> # mt -f /dev/nsa3 status
> Drive: sa3: <SEAGATE DAT    06240-XXX 8071> Serial Number: HJ00YWY
> ---------------------------------
> Mode      Density              Blocksize      bpi      Compression
> Current:  0x26:DDS-4           1024 bytes     97000    enabled (DCLZ)
> ---------------------------------
> Current Driver State: at rest.
> ---------------------------------
> Partition:   0      Calc File Number:  -1     Calc Record Number: -1
> Residual:    0  Reported File Number:  -1 Reported Record Number: -1
> Flags: None
>=20
> But on an LTO-5, which will give long position information, I get:
>=20
> [root@doc ~]# mt status
> Drive: sa0: <IBM ULTRIUM-HH5 E4J1>
> ---------------------------------
> Mode      Density              Blocksize      bpi      Compression
> Current:  0x58:LTO-5           variable       384607   enabled (0x1)
> ---------------------------------
> Current Driver State: at rest.
> ---------------------------------
> Partition:   0      Calc File Number:   2     Calc Record Number: -1
> Residual:    0  Reported File Number:   2 Reported Record Number: =
32373
> Flags: None
>=20
> That, in combination with the changes I made to the position =
information
> code in the driver, mean that even the old MTIOCGET ioctl should =
return an
> accurate file number at end of data.  e.g., on the LTO-5:
>=20
> [root@doc ~]# mt ostatus
> Mode      Density              Blocksize      bpi      Compression
> Current:  0x58:LTO-5           variable       384607   0x1
> ---------available modes---------
> 0:        0x58:LTO-5           variable       384607   0x1
> 1:        0x58:LTO-5           variable       384607   0x1
> 2:        0x58:LTO-5           variable       384607   0x1
> 3:        0x58:LTO-5           variable       384607   0x1
> ---------------------------------
> Current Driver State: at rest.
> ---------------------------------
> File Number: 2  Record Number: -1       Residual Count -1
>=20
> So the thing to try, in addition to just making sure that Bacula =
continues
> to work properly, is to try setting this for the tape drive in
> bacula-sd.conf:
>=20
>  Hardware End of Medium =3D yes
>=20
> It looks like the Bacula tape program (btape) has a test mode, and it =
would
> be good to run through the tests on one of the tape drives and see =
whether
> they work, and whether the results are different before and after the
> changes.  I'm not sure how to enable the test mode.
>=20
>> I'll let the other Bacula devs know about this.  They deal with the =
hardware.  I work on PostgreSQL.
>>=20
>=20
> Thanks!  If there are additional features they would like out of the =
tape
> driver, I'm happy to talk about it.  (Or help if they'd like to use =
the new
> status reporting ioctl, MTIOCEXTGET or any of the other new ioctls.)
>=20
> Ken
> --=20
> Kenneth Merry
> ken@FreeBSD.ORG

=E2=80=94=20
Dan Langille
http://langille.org/








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