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cvdbset(1)                                                        cvdbset(1)




NAME

       cvdbset - A program to control cvdb tracing.


SYNOPSIS

       cvdbset [options]



DESCRIPTION

       cvdbset  is a tool for system administrators to control cvdb(1) tracing
       information from the Xsan File System client file system.

       The level of tracing emitted can be controlled on a per  module  basis.
       The  set  of  modules  for which tracing is enabled is called the trace
       set. The level of tracing can be refined further by specifying a set of
       tracepoints (such as entry/exit points). The set of enabled tracepoints
       is called the logmask.

       Warning: enabling tracing can have a substantial performance impact.

       cvdbset can be used to:

              List all the current client modules in the trace set.

              Add all modules to the trace set.

              Define the trace set.

              Add selected modules to trace set

              Remove selected modules from the trace set

              Set the logmask for a set of modules in the trace set.

              Resize the logging buffer

              Start/stop continuous tracing

              Disable tracing


OPTIONS

       no options
              Display the whether tracing is enabled/disabled, the size of the
              logging  buffer,  the modules in the trace set, and their corre-
              sponding logmasks.

       all    Enable tracing of all modules.  Once cvdbset with a list of mod-
              ules  is invoked, some modules are turned off.  cvdbset all sets
              all modules for tracing.  When used with + or -, add  or  remove
              all modules.

       [:]module1 [:]module2 ...
              When  invoked with a list of modules, cvdbset first disables all
              modules.  Then, it enables exactly the given list of modules. To
              see  all  modules  that  can be enabled, use the cvdbset -l com-
              mand/option. If the module name is preceded by a :, all  modules
              containing the module name will be affected.

       + [:]module1 [:]module2 ...
              When invoked with a plus sign (+) as the first argument followed
              by a list of modules, the given list of modules is added to  the
              current  trace  set.  If the module name is preceded by a :, all
              modules containing the module name will be affected.

       - [:]module1 [:]module2 ...
              When invoked with a minus sign (-) as the  first  argument  fol-
              lowed by a list of modules, the given list of modules is removed
              from the current trace set.  If the module name is preceded by a
              :, all modules containing the module name will be affected.

       -h     Display a help message and exit.

       -c     Enable  continuous cvdb tracing. The trace log will be retrieved
              once per second and placed in files named cvdbout.000001, ...

       -d     Disable cvdb tracing.

       -g     Dump the current trace buffer to standard out.

       -l     Display whether logging is enabled, the  buffer  size,  and  the
              logmask for all modules.

       -L     Display  the  list of all available tracepoints for use with the
              -t option.

       -r mb  Resize the trace buffer to mb megabytes.

       -t tracepoint
              For the indicated modules, enable tracing only for the indicated
              tracepoints.  Multiple  -t  options  can be supplied. Use the -L
              option to cvdbset to see a listing of tracepoints.


EXAMPLES

       To see what modules are in the trace set and their logmasks,  the  com-
       mand  cvdbset with no parameters is used.  Here is the output from this
       command at start-up.

          Debug logging is DISABLED, Bufsize 4194304
          Currently set masks:
          Module '   proxy_clnt' module 0x0000000000000001   logmask 0xffffffffffffffff
          Module '        cvdir' module 0x0000000000000002   logmask 0xffffffffffffffff
          Module '       cvdisk' module 0x0000000000000004   logmask 0xffffffffffffffff
          Module '         cvnc' module 0x0000000000000008   logmask 0xffffffffffffffff
          Module '       cvpath' module 0x0000000000000010   logmask 0xffffffffffffffff
          Module '      portmap' module 0x0000000000000020   logmask 0xffffffffffffffff
          Module '       cvsock' module 0x0000000000000040   logmask 0xffffffffffffffff
          Module '       cvsubr' module 0x0000000000000080   logmask 0xffffffffffffffff
          Module '       dmigfs' module 0x0000000000000100   logmask 0xffffffffffffffff
          Module '         dmig' module 0x0000000000000200   logmask 0xffffffffffffffff
          Module '         dmon' module 0x0000000000000400   logmask 0xffffffffffffffff
          Module '       extapi' module 0x0000000000000800   logmask 0xffffffffffffffff
          Module '       extent' module 0x0000000000001000   logmask 0xffffffffffffffff
          Module '        fsmat' module 0x0000000000002000   logmask 0xffffffffffffffff
          Module '       fsmcom' module 0x0000000000004000   logmask 0xffffffffffffffff
          Module '      fsmdmig' module 0x0000000000008000   logmask 0xffffffffffffffff
          Module '     fsmproxy' module 0x0000000000010000   logmask 0xffffffffffffffff
          Module '      fsmrtio' module 0x0000000000020000   logmask 0xffffffffffffffff
          Module '     fsmtoken' module 0x0000000000040000   logmask 0xffffffffffffffff
          Module '       fsmvfs' module 0x0000000000080000   logmask 0xffffffffffffffff
          Module '     fsmvnops' module 0x0000000000100000   logmask 0xffffffffffffffff
          Module '     memalloc' module 0x0000000000200000   logmask 0xffffffffffffffff
          Module '    proxy_con' module 0x0000000000400000   logmask 0xffffffffffffffff
          Module '       quotas' module 0x0000000000800000   logmask 0xffffffffffffffff
          Module '        recon' module 0x0000000001000000   logmask 0xffffffffffffffff
          Module '         rtio' module 0x0000000002000000   logmask 0xffffffffffffffff
          Module '        rwbuf' module 0x0000000004000000   logmask 0xffffffffffffffff
          Module '      rwproxy' module 0x0000000008000000   logmask 0xffffffffffffffff
          Module '       rwlock' module 0x0000000010000000   logmask 0xffffffffffffffff
          Module '           rw' module 0x0000000020000000   logmask 0xffffffffffffffff
          Module 'slidingbucket' module 0x0000000040000000   logmask 0xffffffffffffffff
          Module '    sockinput' module 0x0000000080000000   logmask 0xffffffffffffffff
          Module '    proxy_srv' module 0x0000000100000000   logmask 0xffffffffffffffff
          Module '   proxy_subr' module 0x0000000200000000   logmask 0xffffffffffffffff
          Module '       vfsops' module 0x0000000400000000   logmask 0xffffffffffffffff
          Module '        vnops' module 0x0000000800000000   logmask 0xffffffffffffffff
          Module '         perf' module 0x0000001000000000   logmask 0xffffffffffffffff
          Module '     md_cvdir' module 0x0000002000000000   logmask 0xffffffffffffffff
          Module '    md_cvsock' module 0x0000004000000000   logmask 0xffffffffffffffff
          Module '    md_cvsubr' module 0x0000008000000000   logmask 0xffffffffffffffff
          Module '      md_dmon' module 0x0000010000000000   logmask 0xffffffffffffffff
          Module '    md_fsmcom' module 0x0000020000000000   logmask 0xffffffffffffffff
          Module '  md_memalloc' module 0x0000040000000000   logmask 0xffffffffffffffff
          Module '    md_rwlock' module 0x0000080000000000   logmask 0xffffffffffffffff
          Module '        md_rw' module 0x0000100000000000   logmask 0xffffffffffffffff
          Module '   md_rwproxy' module 0x0000200000000000   logmask 0xffffffffffffffff
          Module '  md_socksubr' module 0x0000400000000000   logmask 0xffffffffffffffff
          Module '    md_vfsops' module 0x0000800000000000   logmask 0xffffffffffffffff
          Module '     md_vnops' module 0x0001000000000000   logmask 0xffffffffffffffff
          Module '    sh_cvsubr' module 0x0002000000000000   logmask 0xffffffffffffffff
          Module '    sh_fsmcom' module 0x0004000000000000   logmask 0xffffffffffffffff
          Module ' sh_sockinput' module 0x0008000000000000   logmask 0xffffffffffffffff
          Module '     sh_vnops' module 0x0010000000000000   logmask 0xffffffffffffffff


       To enable tracing for selected modules:

               cvdbset md_vnops rw fsmvnops fsmtoken fsmdmig

       This enables tracing for only these five modules and prints the output:

          Setting md_vnops.
          Setting rw.
          Setting fsmvnops.
          Setting fsmtoken.
          Setting fsmdmig.
          cvdb -m modules=0x0001000020148000 logmask=0xffffffffffffffff

       If  an  argument is preceded by a colon (:), then any module whose name
       contains the argument as a substring is included.

       To enable the md_vnops tracing module and all of the proxy-related mod-
       ules:

              cvdbset md_vnops :proxy

       This displays the following output:

          Setting md_vnops.
          Setting proxy_clnt.
          Setting fsmproxy.
          Setting proxy_con.
          Setting rwproxy.
          Setting proxy_srv.
          Setting proxy_subr.
          Setting md_rwproxy.
          cvdb -m modules=0x0001200308410001 logmask=0xffffffffffffffff

       To  add  rwbuf  and  vnops  modules to the current tracing set with the
       cvENTRY and cvEXIT tracepoints enabled:

              cvdbset -t cvENTRY -t cvEXIT + rwbuf vnops

       This displays the following output:

          Adding rwbuf.
          Adding vnops.
          cvdb -m modules=0x0000000804000000 logmask=0x0000000000000003
       To remove rwbuf and vnops from the current tracing set:

              cvdbset - rwbuf vnops

       This displays the following output:

          Clearing rwbuf.
          Clearing vnops.
          cvdb -m modules=0x0000000804000000 logmask=0x0000000000000000

       The special module all can be used with both the +  and  -  options  to
       add/remove all modules from the trace.

       After tracing is enabled, cvdbset -g can be used to retrieve the trace.
       When desired, cvdbset -d can be used to disable tracing.

       Various cvdb(1) command/options can be used for even finer  control  of
       tracing. See cvdb(1) for more details.


I/O PERFORMANCE ANALYSIS

       The  'perf' trace module is very useful to analyze I/O performance, for
       example:

        cvdbset perf

       Then cvdbset -g will display info like this:

               PERF: Device Write 41 MB/s IOs 2 exts 1 offs 0x0 len 0x400000 mics 95589 ino 0x5
               PERF: VFS Write EofDmaAlgn 41 MB/s offs 0x0 len 0x400000 mics 95618 ino 0x5

       The 'PERF: Device' trace shows throughput measured for the device  I/O.
       It also shows the number of I/O's that it was broken into and number of
       extents (sequence of consecutive filesystem blocks).

       The 'PERF: VFS' trace shows throughput measured for the read  or  write
       system call and significant aspects of the I/O including:

              Dma  - DMA
              Buf  - Buffered
              Eof  - File extended
              Algn - Well formed DMA I/O
              Shr  - File is shared by another client
              Rt   - File is real time
              Zr   - Hole in file was zeroed

       Both  traces  also  report  file  offset, I/O size, latency (mics), and
       inode number.

       Sample use cases:

       1) Verify I/O properties are as expected.
          The VFS trace can be used to ensure that  the  displayed  properties
          are consistent with expectations, for example, well formed, buffered
          vs. DMA, shared/non-shared, or I/O size.  If a small  I/O  is  being
          performed DMA then performance will be poor.  If DMA I/O is not well
          formed then it requires an extra data copy and may  even  be  broken
          into small chunks.  Zeroing holes in files has a performance impact.

       2) Determine if metadata operations are impacting performance.
          If VFS throughput is inconsistent or significantly less than  Device
          throughput  then  it  may be caused by metadata operations.  In that
          case it would be  useful  to  display  'fsmtoken',  'fsmvnops',  and
          'fsmdmig' traces in addition to 'perf'.

       3) Identify disk performance issues.
          If  Device  throughput is inconsistent or less than expected then it
          may indicate a slow disk in a storage pool or that  RAID  tuning  is
          necessary.

       4) Identify file fragmentation.
          If the extent count 'exts' is high then it may indicate a fragmenta-
          tion problem.  This causes the device I/O's to broken  into  smaller
          chunks which can significantly impact throughput.

       5) Identify read/modify/write condition.
          If buffered VFS writes are causing Device reads then it may be bene-
          ficial to match I/O request size to a multiple of the 'cachebufsize'
          (default  64KB, see mount_acfs man page).  Another way to avoid this
          is by truncating the file before writing.


SEE ALSO

       cvdb(1)



Xsan File System                  April 2007                       cvdbset(1)

Mac OS X 10.9.1 - Generated Sat Jan 4 18:17:47 CST 2014
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