sa(4) driver changes available for test

Dan Langille dan at langille.org
Sun Mar 1 22:06:40 UTC 2015


> 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.
> 
> ============
> Rough draft commit message:
> 
> http://people.freebsd.org/~ken/sa_changes_commitmsg.20150213.3.txt
> 
> The patches against FreeBSD/head as of SVN revision 278706:
> 
> http://people.freebsd.org/~ken/sa_changes.20150213.3.txt
> 
> And (untested) patches against FreeBSD stable/10 as of SVN revision 278721.
> 
> http://people.freebsd.org/~ken/sa_changes.stable_10.20150213.3.txt
> ============
> 
> The intent is to get the tape infrastructure more up to date, so we can
> support LTFS and more modern tape drives:
> 
> http://www.ibm.com/systems/storage/tape/ltfs/
> 
> I have ported IBM's LTFS Single Drive Edition to FreeBSD.  The port depends
> on the patches linked above.  It isn't fully cleaned up and ready for
> redistribution.  If you're interested, though, let me know and I'll tell
> you when it is ready to go out.  You need an IBM LTO-5, LTO-6, TS1140 or
> TS1150 tape drive.  HP drives aren't supported by IBM's LTFS, and older
> drives don't have the necessary features to support LTFS.
> 
> The commit message below outlines most of the changes.
> 
> A few comments:
> 
> 1. I'm planning to commit the XPT_DEV_ADVINFO changes separately.
> 
> 2. The XML output is similar to what GEOM and CTL do.  It would be nice to
>   figure out how to put a standard schema on it so that standard tools
>   could read it.  I don't know how feasible that is, since I haven't
>   time to dig into it.  If anyone has suggestions on whether that is
>   feasible or advisable, I'd appreciate feedback.
> 
> 3. I have tested with a reasonable amount of tape hardware (see below for a
>   list), but more testing and feedback would be good.
> 
> 4. Standard 'mt status' output looks like this:
> 
> # mt -f /dev/nsa3 status  -v
> Drive: sa3: <IBM ULTRIUM-HH6 E4J1> Serial Number: 101500520A
> ---------------------------------
> Mode      Density              Blocksize      bpi      Compression
> Current:  0x5a:LTO-6           variable       384607   enabled (0xff)
> ---------------------------------
> Current Driver State: at rest.
> ---------------------------------
> Partition:   0      Calc File Number:   0     Calc Record Number: 0
> Residual:    0  Reported File Number:   0 Reported Record Number: 0
> Flags: BOP
> 
> 5. 'mt status -v' looks like this:
> 
> # mt -f /dev/nsa3 status  -v
> Drive: sa3: <IBM ULTRIUM-HH6 E4J1> Serial Number: 101500520A
> ---------------------------------
> Mode      Density              Blocksize      bpi      Compression
> Current:  0x5a:LTO-6           variable       384607   enabled (0xff)
> ---------------------------------
> Current Driver State: at rest.
> ---------------------------------
> Partition:   0      Calc File Number:   0     Calc Record Number: 0
> Residual:    0  Reported File Number:   0 Reported Record Number: 0
> Flags: BOP
> ---------------------------------
> Tape I/O parameters:
>  Maximum I/O size allowed by driver and controller (maxio): 1081344 bytes
>  Maximum I/O size reported by controller (cpi_maxio): 5197824 bytes
>  Maximum block size supported by tape drive and media (max_blk): 8388608 bytes
>  Minimum block size supported by tape drive and media (min_blk): 1 bytes
>  Block granularity supported by tape drive and media (blk_gran): 0 bytes
>  Maximum possible I/O size (max_effective_iosize): 1081344 bytes


# mtx -f /dev/pass0 status
  Storage Changer /dev/pass0:2 Drives, 10 Slots ( 0 Import/Export )
Data Transfer Element 0:Empty
Data Transfer Element 1:Empty
      Storage Element 1:Empty
      Storage Element 2:Empty
      Storage Element 3:Empty
      Storage Element 4:Full :VolumeTag=FAI260                          
      Storage Element 5:Full :VolumeTag=FAI261                          
      Storage Element 6:Full :VolumeTag=FAI262                          
      Storage Element 7:Full :VolumeTag=FAI263                          
      Storage Element 8:Empty
      Storage Element 9:Empty
      Storage Element 10:Empty


It was at this point I spent the next 90 minute trying to get the tape 
drive out of the tape library to free a stuck tape.  Some of this was spent
attempting, and failing, to undo a stripped screw.  I stopped the attempt when
I noticed the screw did need to be removed.  :/





When I do this command, I hear the drive move a bit, to read the tape:

# mt -f /dev/nsa1 status
Drive: sa1: <DEC TZ89     (C) DEC 2561> Serial Number: CXA09S1340
---------------------------------
Mode      Density                Blocksize      bpi      Compression
Current:  0x1b:DLTapeIV(35GB)    variable       85937    enabled (IDRC)
---------------------------------
Current Driver State: at rest.
---------------------------------
Partition:   0      Calc File Number:   0     Calc Record Number: 0
Residual:    0  Reported File Number:  -1 Reported Record Number: -1
Flags: None


# mt -f /dev/nsa1 ostatus  
Mode      Density              Blocksize      bpi      Compression
Current:  0x1b:DLTapeIV(35GB)    variable       85937    IDRC
---------available modes---------
0:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
1:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
2:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
3:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
---------------------------------
Current Driver State: at rest.
---------------------------------
File Number: 0	Record Number: 0	Residual Count 0


After doing a very small tar -c and tar -x, I have:

# mt -f /dev/nsa1 /dev/nsa1 ostatus
Mode      Density              Blocksize      bpi      Compression
Current:  0x1b:DLTapeIV(35GB)    variable       85937    IDRC
---------available modes---------
0:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
1:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
2:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
3:        0x1b:DLTapeIV(35GB)    variable       85937    IDRC
---------------------------------
Current Driver State: at rest.
---------------------------------
File Number: 0	Record Number: 7	Residual Count 0


# mt -f /dev/nsa1 status -v
Drive: sa1: <DEC TZ89     (C) DEC 2561> Serial Number: CXA09S1340
---------------------------------
Mode      Density                Blocksize      bpi      Compression
Current:  0x1b:DLTapeIV(35GB)    variable       85937    enabled (IDRC)
---------------------------------
Current Driver State: at rest.
---------------------------------
Partition:   0      Calc File Number:   0     Calc Record Number: 7
Residual:    0  Reported File Number:  -1 Reported Record Number: -1
Flags: None
---------------------------------
Tape I/O parameters:
  Maximum I/O size allowed by driver and controller (maxio): 65536 bytes
  Maximum I/O size reported by controller (cpi_maxio): 0 bytes
  Maximum block size supported by tape drive and media (max_blk): 16777214 bytes
  Minimum block size supported by tape drive and media (min_blk): 2 bytes
  Block granularity supported by tape drive and media (blk_gran): 0 bytes
  Maximum possible I/O size (max_effective_iosize): 65536 bytes

I may not get to testing Bacula today.  

Based on the above, is there any commands you'd like me to try?


Read below regarding two tape drives

> 
> 6. Existing applications should work without changes.  If not, please let
>   me know.  Hopefully they will move over time to the new interfaces.
> 
> 7. There are lots of additional features that could be added later.
>   Append-only support, encryption, more log pages, etc.
> 
> 8. I have SCSI READ ATTRIBUTE changes for camcontrol(8) that will go in
>   separately.  These changes allow displaying the contents of the MAM
>   (Medium Auxiliary Memory) chips on LTO, TS and other modern tape drives.
>   These are good, and a future possible direction is adding attributes 
>   to the status XML from the sa(4) driver.
> 
> ============
> Significant upgrades to sa(4) and mt(1).
> 
> The primary focus of these changes is to modernize FreeBSD's
> tape infrastructure so that we can take advantage of some of the
> features of modern tape drives and allow support for LTFS.
> 
> Significant changes and new features include:
> 
> o sa(4) driver status and parameter information is now exported via an
>   XML structure.  This will allow for changes and improvements later
>   on that will not break userland applications.  The old MTIOCGET
>   status ioctl remains, so applications using the existing interface
>   will not break.
> 
> o 'mt status' now reports drive-reported tape position information
>   as well as the previously available calculated tape position
>   information.  These numbers will be different at times, because
>   the drive-reported block numbers are relative to BOP (Beginning
>   of Partition), but the block numbers calculated previously via
>   sa(4) (and still provided) are relative to the last filemark.
>   Both numbers are now provided.  'mt status' now also shows the
>   drive INQUIRY information, serial number and any position flags
>   (BOP, EOT, etc.) provided with the tape position information.
>   'mt status -v' adds information on the maximum possible I/O size,
>   and the underlying values used to calculate it.
> 
> o The extra sa(4) /dev entries (/dev/saN.[0-3]) have been removed.

How does this affect a tape library with more than one tape drive?

[root at cuppy:~] # camcontrol amcontrol devlist
<DEC TL800    (C) DEC 0525>        at scbus0 target 0 lun 0 (pass0,ch0)
<DEC TZ89     (C) DEC 2561>        at scbus0 target 2 lun 0 (sa1,pass2)
<WDC WD5000AAKS-00YGA0 12.01C02>   at scbus1 target 0 lun 0 (pass3,ada0)
<WDC WD5000AAKS-00YGA0 12.01C02>   at scbus2 target 0 lun 0 (pass4,ada1)
<AHCI SGPIO Enclosure 1.00 0001>   at scbus3 target 0 lun 0 (pass5,ses0)

This system has two tapes drives and I can access them through the front panel but:

# ls -l /dev/*sa*
crw-rw----  1 root  operator  0x65 Feb 28 22:04 /dev/esa1
crw-rw----  1 root  operator  0x64 Mar  1 22:43 /dev/nsa1
crw-rw----  1 root  operator  0x63 Feb 28 22:04 /dev/sa1
crw-rw----  1 root  operator  0x62 Feb 28 22:04 /dev/sa1.ctl

... only one tape drives shows up.


> 
>   The extra devices were originally added as place holders for
>   density-specific device nodes.  Some OSes (NetBSD, NetApp's OnTap
>   and Solaris) have had device nodes that, when you write to them,
>   will automatically select a given density for particular tape drives.
> 
>   This is a convenient way of switching densities, but it was never
>   implemented in FreeBSD.  Only the device nodes were there, and that
>   sometimes confused users.
> 
>   For modern tape devices, the density is generally not selectable
>   (e.g. with LTO) or defaults to the highest availble density when
>   the tape is rewritten from BOT (e.g. TS11X0).  So, for most users,
>   density selection won't be necessary.  If they do need to select
>   the density, it is easy enough to use 'mt density' to change it.
> 
> o Protection information is now supported.  This is either a
>   Reed-Solomon CRC or CRC32 that is included at the end of each block
>   read and written.  On write, the tape drive verifies the CRC, and
>   on read, the tape drive provides a CRC for the userland application
>   to verify.
> 
> o New, extensible tape driver parameter get/set interface.
> 
> o Density reporting information.  For drives that support it,
>   'mt getdensity' will show detailed information on what formats the
>   tape drive supports, and what formats the tape drive supports.
> 
> o Some mt(1) functionality moved into a new mt(3) library so that
>   external applications can reuse the code.
> 
> o The new mt(3) library includes helper routines to aid in parsing
>   the XML output of the sa(4) driver, and build a tree of driver
>   metadata.
> 
> o Support for the MTLOAD (load a tape in the drive) and MTWEOFI
>   (write filemark immediate) ioctls needed by IBM's LTFS
>   implementation.
> 
> o Improve device departure behavior for the sa(4) driver.  The previous
>   implementation led to hangs when the device was open.
> 
> o This has been tested on the following types of drives:
> 	IBM TS1150
> 	IBM TS1140
> 	IBM LTO-6
> 	IBM LTO-5
> 	HP LTO-2
> 	Seagate DDS-4
> 	Quantum DLT-4000
> 	Exabyte 8505
> 	Sony DDS-2
> 
> contrib/groff/tmac/doc-syms,
> share/mk/bsd.libnames.mk,
> lib/Makefile,
> 	Add libmt.
> 
> lib/libmt/Makefile,
> lib/libmt/mt.3,
> lib/libmt/mtlib.c,
> lib/libmt/mtlib.h,
> 	New mt(3) library that contains functions moved from mt(1) and
> 	new functions needed to interact with the updated sa(4) driver.
> 
> 	This includes XML parser helper functions that application writers
> 	can use when writing code to query tape parameters.
> 
> rescue/rescue/Makefile:
> 	Add -lmt to CRUNCH_LIBS.
> 
> sys/cam/cam_ccb.h
> 	Add a new flag value for the XPT_DEV_ADVINFO CCB, CDAI_FLAG_NONE.
> 
> sbin/camcontrol/camcontrol.c,
> sys/cam/scsi/scsi_da.c,
> sys/cam/scsi/scsi_enc_ses.c,
> sys/dev/mps/mps_sas.c:
> 	Make sure the flags for the XPT_DEV_ADVINFO CCB are set correctly.
> 	This prevents unintended attempts to set advanced information
> 	values when XPT_DEV_ADVINFO CCBs are not pre-zeroed.
> 
> src/share/man/man4/mtio.4
> 	Clarify this man page a bit, and since it contains what is
> 	essentially the mtio.h header file, add new ioctls and structure
> 	definitions from mtio.h.
> 
> src/share/man/man4/sa.4
> 	Update BUGS and maintainer section.
> 
> sys/cam/scsi/scsi_all.c,
> sys/cam/scsi/scsi_all.h:
> 	Add SCSI SECURITY PROTOCOL IN/OUT CDB definitions and CDB building
> 	functions.
> 
> sys/cam/scsi/scsi_sa.c
> sys/cam/scsi/scsi_sa.h
> 	Many tape driver changes, largely outlined above.
> 
> 	Increase the sa(4) driver read/write timeout from 4 to 32
> 	minutes.  This is based on the recommended values for IBM LTO
> 	5/6 drives.  This may also avoid timeouts for other tape
> 	hardware that can take a long time to do retries and error
> 	recovery.  Longer term, a better way to handle this is to ask
> 	the drive for recommended timeout values using the REPORT
> 	SUPPORTED OPCODES command.  Modern IBM and Oracle tape drives
> 	at least support that command, and it would allow for more
> 	accurate timeout values.
> 
> 	Add XML status generation.  This is done with a series of
> 	macros to eliminate as much duplicate code as possible.  The
> 	new XML-based status values are reported through the new
> 	MTIOCEXTGET ioctl.
> 
> 	Add XML driver parameter reporting, using the new MTIOCPARAMGET
> 	ioctl.
> 
> 	Add a new driver parameter setting interface, using the new
> 	MTIOCPARAMSET and MTIOCSETLIST ioctls.
> 
> 	Add a new MTIOCRBLIM ioctl to get block limits information.
> 
> 	Add CCB/CDB building routines scsi_locate_16, scsi_locate_10,
> 	and scsi_read_position_10().
> 
> 	scsi_locate_10 implements the LOCATE command, as does the
> 	existing scsi_set_position() command.  It just supports
> 	additional arguments and features.  If/when we figure out a
> 	good way to provide backward compatibility for older
> 	applications using the old function API, we can just revamp
> 	scsi_set_position().  The same goes for
> 	scsi_read_position_10() and the existing scsi_read_position()
> 	function.
> 
> 	Revamp sasetpos() to take the new mtlocate structure as an
> 	argument.  It now will use either scsi_locate_10() or
> 	scsi_locate_16(), depending upon the arguments the user
> 	supplies.  As before, once we change position we don't have a
> 	clear idea of what the current logical position of the tape
> 	drive is.
> 
> 	For tape drives that support long form position data, we
> 	read the current position and store that for later reporting
> 	after changing the position.  This should help applications
> 	like Bacula speed tape access under FreeBSD once they are
> 	modified to support the new ioctls.
> 
> 	Add a new quirk, SA_QUIRK_NO_LONG_POS, that is set for all
> 	drives that report SCSI-2 or older, as well as drives that
> 	report an Illegal Request type error for READ POSITION with
> 	the long format.  So we should automatically detect drives
> 	that don't support the long form and stop asking for it after
> 	an initial try.
> 
> 	Add a partition number to the sa(4) softc.
> 
> 	Improve device departure handling. The previous implementation
> 	led to hangs when the device was open.
> 
> 	If an application had the sa(4) driver open, and attempted to
> 	close it after it went away, the cam_periph_release() call in
> 	saclose() would cause the periph to get destroyed because that
> 	was the last reference to it.  Because destroy_dev() was
> 	called from the sa(4) driver's cleanup routine (sacleanup()),
> 	and would block waiting for the close to happen, a deadlock
> 	would result.
> 
> 	So instead of calling destroy_dev() from the cleanup routine,
> 	call destroy_dev_sched_cb() from saoninvalidate() and wait for
> 	the callback.
> 
> 	Acquire a reference for devfs in saregister(), and release it
> 	in the new sadevgonecb() routine when all devfs devices for	
> 	the particular sa(4) driver instance are gone.
> 
> 	Add a new function, sasetupdev(), to centralize setting
> 	per-instance devfs device parameters instead of repeating the
> 	code in saregister().
> 
> 	Add an open count to the softc, so we know how many
> 	peripheral driver references are a result of open
>       	sessions.
> 
> 	Add the D_TRACKCLOSE flag to the cdevsw flags so
> 	that we get a 1:1 mapping of open to close calls
> 	instead of a N:1 mapping.
> 
> 	This should be a no-op for everything except the
> 	control device, since we don't allow more than one
> 	open on non-control devices.
> 
> 	However, since we do allow multiple opens on the
> 	control device, the combination of the open count
> 	and the D_TRACKCLOSE flag should result in an
> 	accurate peripheral driver reference count, and an
> 	accurate open count.
> 
> 	The accurate open count allows us to release all
> 	peripheral driver references that are the result
> 	of open contexts once we get the callback from devfs.
> 
> sys/sys/mtio.h:
> 	Add a number of new mt(4) ioctls and the requisite data
> 	structures.  None of the existing interfaces been removed
> 	or changed.
> 
> 	This includes definitions for the following new ioctls:
> 
> 	MTIOCRBLIM      /* get block limits */
> 	MTIOCEXTLOCATE	/* seek to position */
> 	MTIOCEXTGET     /* get tape status */
> 	MTIOCPARAMGET	/* get tape params */
> 	MTIOCPARAMSET	/* set tape params */
> 	MTIOCSETLIST	/* set N params */
> 
> usr.bin/mt/Makefile:
> 	mt(1) now depends on libmt, libsbuf and libbsdxml.
> 
> usr.bin/mt/mt.1:
> 	Document new mt(1) features and subcommands.
> 
> usr.bin/mt/mt.c:
> 	Implement support for mt(1) subcommands that need to
> 	use getopt(3) for their arguments.
> 
> 	Implement a new 'mt status' command to replace the old
> 	'mt status' command.  The old status command has been
> 	renamed 'ostatus'.
> 
> 	The new status function uses the MTIOCEXTGET ioctl, and
> 	therefore parses the XML data to determine drive status.
> 	The -x argument to 'mt status' allows the user to dump out
> 	the raw XML reported by the kernel.
> 
> 	The new status display is mostly the same as the old status
> 	display, except that it doesn't print the redundant density
> 	mode information, and it does print the current partition
> 	number and position flags.
> 
> 	Add a new command, 'mt locate', that will supersede the
> 	old 'mt setspos' and 'mt sethpos' commands.  'mt locate'
> 	implements all of the functionality of the MTIOCEXTLOCATE
> 	ioctl, and allows the user to change the logical position
> 	of the tape drive in a number of ways.  (Partition,
> 	block number, file number, set mark number, end of data.)
> 	The immediate bit and the explicit address bits are
> 	implemented, but not documented in the man page.
> 
> 	Add a new 'mt weofi' command to use the new MTWEOFI ioctl.
> 	This allows the user to ask the drive to write a filemark
> 	without waiting around for the operation to complete.
> 
> 	Add a new 'mt getdensity' command that gets the XML-based
> 	tape drive density report from the sa(4) driver and displays
> 	it.  This uses the SCSI REPORT DENSITY SUPPORT command
> 	to get comprehensive information from the tape drive about
> 	what formats it is able to read and write.
> 
> 	Add a new 'mt protect' command that allows getting and setting
> 	tape drive protection information.  The protection information
> 	is a CRC tacked on to the end of every read/write from and to
> 	the tape drive.
> 
> Sponsored by:	Spectra Logic
> MFC after:	1 month
> 
> Thanks,
> 
> Ken
> -- 
> Kenneth Merry
> ken at FreeBSD.ORG
> _______________________________________________
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— 
Dan Langille
http://langille.org/







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