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CVDBSET(1M)                                                                                      CVDBSET(1M)



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  log-mask. logmask.
       mask.

       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 corresponding logmasks.

       all    Enable tracing of all modules.  Once cvdbset with a list of modules 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
              command/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 followed 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 command 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 sub-string substring
       string is included.

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

              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 expecta-tions, expectations,
          tions, 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 fragmentation 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 beneficial 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(1M)