sa(4) driver changes available for test

[Dan Langille]

> On Feb 17, 2015, at 1:36 PM, Kenneth D. Merry <ken at freebsd.org> wrote:
> 
> On Sat, Feb 14, 2015 at 18:22:43 -0500, Dan Langille wrote:
>> 
>>> On Feb 13, 2015, at 7:32 PM, Kenneth D. Merry <ken at freebsd.org> wrote:
>>> 
>>> 
>>> 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.
>>> 
>>> A description of the changes is here and below in this message.
>>> 
>>> If you have tape hardware and the inclination, I'd appreciate testing and
>>> feedback.
>> 
>> I have a DLT 8000 and an SDLT 220.
>> 
>> I don't have anything running current, but I have a spare machine which I could use for testing.
>> 
>> Do you see any value is tests with that hardware? I'd be testing it via Bacula.
>> 
>> disclosure: I'm the sysutils/bacula-* maintainer and a Bacula committer.
>> 
> 
> 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.


> 
> 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.
> 
> You can see what I'm talking about by doing:
> 
> mt eod
> mt status
> 
> On my DDS-4 tape drive, this shows:
> 
> # 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
> 
> But on an LTO-5, which will give long position information, I get:
> 
> [root at 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
> 
> 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:
> 
> [root at 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
> 
> 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:
> 
>  Hardware End of Medium = yes
> 
> 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.
> 
>> I'll let the other Bacula devs know about this.  They deal with the hardware.  I work on PostgreSQL.
>> 
> 
> 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.)
> 
> Ken
> -- 
> Kenneth Merry
> ken at FreeBSD.ORG

— 
Dan Langille
http://langille.org/